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  • Is there a free, smale-scale, not web-based issue/bug tracking system?

    - by Doc Brown
    I know, there were posts before here on SO before concerning issue or bug tracking systems, like this one, but the given answers point either to commercial systems or web-based systems, which both seem to be oversized for our needs. What I am looking for is a non-commercial tool for a team of 3 to 4 developers, which can be used on an existing fileserver, without the need of installing additional server software like a C/S database or a web server. Some things I expect from such a system: allows to remember bugs (with a priority) and issues / ideas for new features (mostly without a priority) description of the issue, perhaps some additional remarks short info who entered the bug/issue entry one or more tags allowing us to group or filter the list Any suggestions? EDIT: I should have said that, but we are using MS Windows clients, Visual Studio development, Tortoise SVN (the latter works fine without a subversion server). And yes, I am strict on "no server software", since all server based solutions I have seen so far seem much to oversized/heavy weighted/too-much-effort-to-be-worth-it. In fact, if no one has a better idea, we are going to use a spreadsheet, but I can't believe there are no ready-made, light weight solutions.

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  • Ways to make (relatively) safe assumptions about the type of concrete subclasses?

    - by Kylotan
    I have an interface (defined as a abstract base class) that looks like this: class AbstractInterface { public: bool IsRelatedTo(const AbstractInterface& other) const = 0; } And I have an implementation of this (constructors etc omitted): class ConcreteThing { public: bool IsRelatedTo(const AbstractInterface& other) const { return m_ImplObject.has_relationship_to(other.m_ImplObject); } private: ImplementationObject m_ImplObject; } The AbstractInterface forms an interface in Project A, and the ConcreteThing lives in Project B as an implementation of that interface. This is so that code in Project A can access data from Project B without having a direct dependency on it - Project B just has to implement the correct interface. Obviously the line in the body of the IsRelatedTo function cannot compile - that instance of ConcreteThing has an m_ImplObject member, but it can't assume that all AbstractInterfaces do, including the other argument. In my system, I can actually assume that all implementations of AbstractInterface are instances of ConcreteThing (or subclasses thereof), but I'd prefer not to be casting the object to the concrete type in order to get at the private member, or encoding that assumption in a way that will crash without a diagnostic later if this assumption ceases to hold true. I cannot modify ImplementationObject, but I can modify AbstractInterface and ConcreteThing. I also cannot use the standard RTTI mechanism for checking a type prior to casting, or use dynamic_cast for a similar purpose. I have a feeling that I might be able to overload IsRelatedTo with a ConcreteThing argument, but I'm not sure how to call it via the base IsRelatedTo(AbstractInterface) method. It wouldn't get called automatically as it's not a strict reimplementation of that method. Is there a pattern for doing what I want here, allowing me to implement the IsRelatedTo function via ImplementationObject::has_relationship_to(ImplementationObject), without risky casts? (Also, I couldn't think of a good question title - please change it if you have a better one.)

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  • isalpha(<mychar>) == true evaluates to false??

    - by Buttink
    string temp is equal to "ZERO:\t.WORD\t1" from my debugger. (the first line of my file) string temp = RemoveWhiteSpace(data); int i = 0; if ( temp.length() > 0 && isalpha(temp[0]) ) cout << "without true worked" << endl; if ( temp.length() > 0 && isalpha(temp[0]) == true ) cout << "with true worked" << endl; This is my code to check if first character of temp is a a-z,A-Z. The first if statement will evaluate to true and the 2nd to false. WHY?!?!?! I have tried this even without the "temp.length() 0 &&" and it still evaluates false. It just hates the "== true". The only thing I can think of is that isalpha() returns != 0 and true == 1. Then, you could get isalpha() == 2 != 1. But, I have no idea if C++ is that ... weird. BTW, I dont need to know that the "== true" is logically pointless. I know. output was without true worked Compiled with CodeBlock using GNU GCC on Ubuntu 9.10 (if this matters any)

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  • Tools and Utilities for the .NET Developer

    - by mbcrump
    Tweet this list! Add a link to my site to your bookmarks to quickly find this page again! Add me to twitter! This is a list of the tools/utilities that I use to do my job/hobby. I wanted this page to load fast and contain information that only you care about. If I have missed a tool that you like, feel free to contact me and I will add it to the list. Also, this list took a lot of time to complete. Please do not steal my work, if you like the page then please link back to my site. I will keep the links/information updated as new tools/utilities are created.  Windows/.NET Development – This is a list of tools that any Windows/.NET developer should have in his bag. I have used at some point in my career everything listed on this page and below is the tools worth keeping. Name Description License AnkhSVN Subversion support for Visual Studio. It also works with VS2010. Free Aurora XAML Designer One of the best XAML creation tools available. Has a ton of built in templates that you can copy/paste into VS2010. COST/Trial BeyondCompare Beyond Compare 3 is the ideal tool for comparing files and folders on your Windows or Linux system. Visualize changes in your code and carefully reconcile them. COST/Trial BuildIT Automated Task Tool Its main purpose is to automate tasks, whether it is the final packaging of a product, an automated daily build, maybe sending out a mailing list, even backing-up files. Free C Sharper for VB Convert VB to C#. COST CLRProfiler Analyze and improve the behavior of your .NET app. Free CodeRush Direct competitor to ReSharper, contains similar feature. This is one of those decide for yourself. COST/Trial Disk2VHD Disk2vhd is a utility that creates VHD (Virtual Hard Disk - Microsoft's Virtual Machine disk format) versions of physical disks for use in Microsoft Virtual PC or Microsoft Hyper-V virtual machines (VMs). Free Eazfuscator.NET Is a free obfuscator for .NET. The main purpose is to protect intellectual property of software. Free EQATEC Profiler Make your .NET app run faster. No source code changes are needed. Just point the profiler to your app, run the modified code, and get a visual report. COST Expression Studio 3/4 Comes with Web, Blend, Sketch Flow and more. You can create websites, produce beautiful XAML and more. COST/Trial Expresso The award-winning Expresso editor is equally suitable as a teaching tool for the beginning user of regular expressions or as a full-featured development environment for the experienced programmer or web designer with an extensive knowledge of regular expressions. Free Fiddler Fiddler is a web debugging proxy which logs all HTTP(s) traffic between your computer and the internet. Free Firebug Powerful Web development tool. If you build websites, you will need this. Free FxCop FxCop is an application that analyzes managed code assemblies (code that targets the .NET Framework common language runtime) and reports information about the assemblies, such as possible design, localization, performance, and security improvements. Free GAC Browser and Remover Easy way to remove multiple assemblies from the GAC. Assemblies registered by programs like Install Shield can also be removed. Free GAC Util The Global Assembly Cache tool allows you to view and manipulate the contents of the global assembly cache and download cache. Free HelpScribble Help Scribble is a full-featured, easy-to-use help authoring tool for creating help files from start to finish. You can create Win Help (.hlp) files, HTML Help (.chm) files, a printed manual and online documentation (on a web site) all from the same Help Scribble project. COST/Trial IETester IETester is a free Web Browser that allows you to have the rendering and JavaScript engines of IE9 preview, IE8, IE7 IE 6 and IE5.5 on Windows 7, Vista and XP, as well as the installed IE in the same process. Free iTextSharp iText# (iTextSharp) is a port of the iText open source java library for PDF generation written entirely in C# for the .NET platform. Use the iText mailing list to get support. Free Kaxaml Kaxaml is a lightweight XAML editor that gives you a "split view" so you can see both your XAML and your rendered content. Free LINQPad LinqPad lets you interactively query databases in a LINQ. Free Linquer Many programmers are familiar with SQL and will need a help in the transition to LINQ. Sometimes there are complicated queries to be written and Linqer can help by converting SQL scripts to LINQ. COST/Trial LiquidXML Liquid XML Studio 2010 is an advanced XML developers toolkit and IDE, containing all the tools needed for designing and developing XML schema and applications. COST/Trial Log4Net log4net is a tool to help the programmer output log statements to a variety of output targets. log4net is a port of the excellent log4j framework to the .NET runtime. We have kept the framework similar in spirit to the original log4j while taking advantage of new features in the .NET runtime. For more information on log4net see the features document. Free Microsoft Web Platform Installer The Microsoft Web Platform Installer 2.0 (Web PI) is a free tool that makes getting the latest components of the Microsoft Web Platform, including Internet Information Services (IIS), SQL Server Express, .NET Framework and Visual Web Developer easy. Free Mono Development Don't have Visual Studio - no problem! This is an open Source C# and .NET development environment for Linux, Windows, and Mac OS X Free Net Mass Downloader While it’s great that Microsoft has released the .NET Reference Source Code, you can only get it one file at a time while you’re debugging. If you’d like to batch download it for reading or to populate the cache, you’d have to write a program that instantiated and called each method in the Framework Class Library. Fortunately, .NET Mass Downloader comes to the rescue! Free nMap Nmap ("Network Mapper") is a free and open source (license) utility for network exploration or security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Free NoScript (Firefox add-in) The NoScript Firefox extension provides extra protection for Firefox, Flock, Seamonkey and other Mozilla-based browsers: this free, open source add-on allows JavaScript, Java and Flash and other plug-ins to be executed only by trusted web sites of your choice (e.g. your online bank), and provides the most powerful Anti-XSS protection available in a browser. Free NotePad 2 Notepad2, a fast and light-weight Notepad-like text editor with syntax highlighting. This program can be run out of the box without installation, and does not touch your system's registry. Free PageSpy PageSpy is a small add-on for Internet Explorer that allows you to select any element within a webpage, select an option in the context menu, and view detailed information about both the coding behind the page and the element you selected. Free Phrase Express PhraseExpress manages your frequently used text snippets in customizable categories for quick access. Free PowerGui PowerGui is a free community for PowerGUI, a graphical user interface and script editor for Microsoft Windows PowerShell! Free Powershell Comes with Win7, but you can automate tasks by using the .NET Framework. Great for network admins. Free Process Explorer Ever wondered which program has a particular file or directory open? Now you can find out. Process Explorer shows you information about which handles and DLLs processes have opened or loaded. Also, included in the SysInterals Suite. Free Process Monitor Process Monitor is an advanced monitoring tool for Windows that shows real-time file system, Registry and process/thread activity. Free Reflector Explore and analyze compiled .NET assemblies, viewing them in C#, Visual Basic, and IL. This is an Essential for any .NET developer. Free Regular Expression Library Stuck on a Regular Expression but you think someone has already figured it out? Chances are they have. Free Regulator Regulator makes Regular Expressions easy. This is a must have for a .NET Developer. Free RenameMaestro RenameMaestro is probably the easiest batch file renamer you'll find to instantly rename multiple files COST ReSharper The one program that I cannot live without. Supports VS2010 and offers simple refactoring, code analysis/assistance/cleanup/templates. One of the few applications that is worth the $$$. COST/Trial ScrewTurn Wiki ScrewTurn Wiki allows you to create, manage and share wikis. A wiki is a collaboratively-edited, information-centered website: the most famous is Wikipedia. Free SharpDevelop What is #develop? SharpDevelop is a free IDE for C# and VB.NET projects on Microsoft's .NET platform. Free Show Me The Template Show Me The Template is a tool for exploring the templates, be their data, control or items panel, that comes with the controls built into WPF for all 6 themes. Free SnippetCompiler Compiles code snippets without opening Visual Studio. It does not support .NET 4. Free SQL Prompt SQL Prompt is a plug-in that increases how fast you can work with SQL. It provides code-completion for SQL server, reformatting, db schema information and snippets. Awesome! COST/Trial SQLinForm SQLinForm is an automatic SQL code formatter for all major databases  including ORACLE, SQL Server, DB2, UDB, Sybase, Informix, PostgreSQL, Teradata, MySQL, MS Access etc. with over 70 formatting options. COST/OnlineFree SSMS Tools SSMS Tools Pack is an add-in for Microsoft SQL Server Management Studio (SSMS) including SSMS Express. Free Storm STORM is a free and open source tool for testing web services. Free Telerik Code Convertor Convert code from VB to C Sharp and Vice Versa. Free TurtoiseSVN TortoiseSVN is a really easy to use Revision control / version control / source control software for Windows.Since it's not an integration for a specific IDE you can use it with whatever development tools you like. Free UltraEdit UltraEdit is the ideal text, HTML and hex editor, and an advanced PHP, Perl, Java and JavaScript editor for programmers. UltraEdit is also an XML editor including a tree-style XML parser. An industry-award winner, UltraEdit supports disk-based 64-bit file handling (standard) on 32-bit Windows platforms (Windows 2000 and later). COST/Trial Virtual Windows XP Comes with some W7 version and allows you to run WinXP along side W7. Free VirtualBox Virtualization by Sun Microsystems. You can virtualize Windows, Linux and more. Free Visual Log Parser SQL queries against a variety of log files and other system data sources. Free WinMerge WinMerge is an Open Source differencing and merging tool for Windows. WinMerge can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle. Free Wireshark Wireshark is one of the best network protocol analyzer's for Unix and windows. This has been used several times to get me out of a bind. Free XML Notepad 07 Old, but still one of my favorite XML viewers. Free Productivity Tools – This is the list of tools that I use to save time or quickly navigate around Windows. Name Description License AutoHotKey Automate almost anything by sending keystrokes and mouse clicks. You can write a mouse or keyboard macro by hand or use the macro recorder. Free CLCL CLCL is clipboard caching utility. Free Ditto Ditto is an extension to the standard windows clipboard. It saves each item placed on the clipboard allowing you access to any of those items at a later time. Ditto allows you to save any type of information that can be put on the clipboard, text, images, html, custom formats, ..... Free Evernote Remember everything from notes to photos. It will synch between computers/devices. Free InfoRapid Inforapid is a search tool that will display all you search results in a html like browser. If you click on a word in that browser, it will start another search to the word you clicked on. Handy if you want to trackback something to it's true origin. The word you looked for will be highlighted in red. Clicking on the red word will open the containing file in a text based viewer. Clicking on any word in the opened document will start another search on that word. Free KatMouse The prime purpose of the KatMouse utility is to enhance the functionality of mice with a scroll wheel, offering 'universal' scrolling: moving the mouse wheel will scroll the window directly beneath the mouse cursor (not the one with the keyboard focus, which is default on Windows OSes). This is a major increase in the usefulness of the mouse wheel. Free ScreenR Instant Screencast with nothing to download. Works with Mac or PC and free. Free Start++ Start++ is an enhancement for the Start Menu in Windows Vista. It also extends the Run box and the command-line with customizable commands.  For example, typing "w Windows Vista" will take you to the Windows Vista page on Wikipedia! Free Synergy Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware. It's intended for users with multiple computers on their desk since each system uses its own monitor(s). Free Texter Texter lets you define text substitution hot strings that, when triggered, will replace hotstring with a larger piece of text. By entering your most commonly-typed snippets of text into Texter, you can save countless keystrokes in the course of the day. Free Total Commander File handling, FTP, Archive handling and much more. Even works with Win3.11. COST/Trial Available Wizmouse WizMouse is a mouse enhancement utility that makes your mouse wheel work on the window currently under the mouse pointer, instead of the currently focused window. This means you no longer have to click on a window before being able to scroll it with the mouse wheel. This is a far more comfortable and practical way to make use of the mouse wheel. Free Xmarks Bookmark sync and search between computers. Free General Utilities – This is a list for power user users or anyone that wants more out of Windows. I usually install a majority of these whenever I get a new system. Name Description License µTorrent µTorrent is a lightweight and efficient BitTorrent client for Windows or Mac with many features. I use this for downloading LEGAL media. Free Audacity Audacity® is free, open source software for recording and editing sounds. It is available for Mac OS X, Microsoft Windows, GNU/Linux, and other operating systems. Learn more about Audacity... Also check our Wiki and Forum for more information. Free AVast Free FREE Antivirus. Free CD Burner XP Pro CDBurnerXP is a free application to burn CDs and DVDs, including Blu-Ray and HD-DVDs. It also includes the feature to burn and create ISOs, as well as a multilanguage interface. Free CDEX You can extract digital audio CDs into mp3/wav. Free Combofix Combofix is a freeware (a legitimate spyware remover created by sUBs), Combofix was designed to scan a computer for known malware, spyware (SurfSideKick, QooLogic, and Look2Me as well as any other combination of the mentioned spyware applications) and remove them. Free Cpu-Z Provides information about some of the main devices of your system. Free Cropper Cropper is a screen capture utility written in C#. It makes it fast and easy to grab parts of your screen. Use it to easily crop out sections of vector graphic files such as Fireworks without having to flatten the files or open in a new editor. Use it to easily capture parts of a web site, including text and images. It's also great for writing documentation that needs images of your application or web site. Free DropBox Drag and Drop files to sync between computers. Free DVD-Fab Converts/Copies DVDs/Blu-Ray to different formats. (like mp4, mkv, avi) COST/Trial Available FastStone Capture FastStone Capture is a powerful, lightweight, yet full-featured screen capture tool that allows you to easily capture and annotate anything on the screen including windows, objects, menus, full screen, rectangular/freehand regions and even scrolling windows/web pages. Free ffdshow FFDShow is a DirectShow decoding filter for decompressing DivX, XviD, H.264, FLV1, WMV, MPEG-1 and MPEG-2, MPEG-4 movies. Free Filezilla FileZilla Client is a fast and reliable cross-platform FTP, FTPS and SFTP client with lots of useful features and an intuitive graphical user interface. You can also download a server version. Free FireFox Web Browser, do you really need an explanation? Free FireGestures A customizable mouse gestures extension which enables you to execute various commands and user scripts with five types of gestures. Free FoxIt Reader Light weight PDF viewer. You should install this with the advanced setting or it will install a toolbar and setup some shortcuts. Free gSynchIt Synch Gmail and Outlook. Even supports Outlook 2010 32/64 bit COST/Trial Available Hulu Desktop At home or in a hotel, this has replaced my cable/satellite subscription. Free ImgBurn ImgBurn is a lightweight CD / DVD / HD DVD / Blu-ray burning application that everyone should have in their toolkit! Free Infrarecorder InfraRecorder is a free CD/DVD burning solution for Microsoft Windows. It offers a wide range of powerful features; all through an easy to use application interface and Windows Explorer integration. Free KeePass KeePass is a free open source password manager, which helps you to manage your passwords in a secure way. Free LastPass Another password management, synchronize between browsers, automatic form filling and more. Free Live Essentials One download and lots of programs including Mail, Live Writer, Movie Maker and more! Free Monitores MonitorES is a small windows utility that helps you to turnoff monitor display when you lock down your machine.Also when you lock your machine, it will pause all your running media programs & set your IM status message to "Away" / Custom message(via options) and restore it back to normal when you back. Free mRemote mRemote is a full-featured, multi-tab remote connections manager. Free Open Office OpenOffice.org 3 is the leading open-source office software suite for word processing, spreadsheets, presentations, graphics, databases and more. It is available in many languages and works on all common computers. It stores all your data in an international open standard format and can also read and write files from other common office software packages. It can be downloaded and used completely free of charge for any purpose. Free Paint.NET Simple, intuitive, and innovative user interface for editing photos. Free Picasa Picasa is free photo editing software from Google that makes your pictures look great. Free Pidgin Pidgin is an easy to use and free chat client used by millions. Connect to AIM, MSN, Yahoo, and more chat networks all at once. Free PING PING is a live Linux ISO, based on the excellent Linux From Scratch (LFS) documentation. It can be burnt on a CD and booted, or integrated into a PXE / RIS environment. Free Putty PuTTY is an SSH and telnet client, developed originally by Simon Tatham for the Windows platform. Free Revo Uninstaller Revo Uninstaller Pro helps you to uninstall software and remove unwanted programs installed on your computer easily! Even if you have problems uninstalling and cannot uninstall them from "Windows Add or Remove Programs" control panel applet.Revo Uninstaller is a much faster and more powerful alternative to "Windows Add or Remove Programs" applet! It has very powerful features to uninstall and remove programs. Free Security Essentials Microsoft Security Essentials is a new, free consumer anti-malware solution for your computer. Free SetupVirtualCloneDrive Virtual CloneDrive works and behaves just like a physical CD/DVD drive, however it exists only virtually. Point to the .ISO file and it appears in Windows Explorer as a Drive. Free Shark 007 Codec Pack Play just about any file format with this download. Also includes my W7 Media Playlist Generator. Free Snagit 9 Screen Capture on steroids. Add arrows, captions, etc to any screenshot. COST/Trial Available SysinternalsSuite Go ahead and download the entire sys internals suite. I have mentioned multiple programs in this suite already. Free TeraCopy TeraCopy is a compact program designed to copy and move files at the maximum possible speed, providing the user with a lot of features. Free for Home TrueCrypt Free open-source disk encryption software for Windows 7/Vista/XP, Mac OS X, and Linux Free TweetDeck Fully featured Twitter client. Free UltraVNC UltraVNC is a powerful, easy to use and free software that can display the screen of another computer (via internet or network) on your own screen. The program allows you to use your mouse and keyboard to control the other PC remotely. It means that you can work on a remote computer, as if you were sitting in front of it, right from your current location. Free Unlocker Unlocks locked files. Pretty simple right? Free VLC Media Player VLC media player is a highly portable multimedia player and multimedia framework capable of reading most audio and video formats Free Windows 7 Media Playlist This program is special to my heart because I wrote it. It has been mentioned on podcast and various websites. It allows you to quickly create wvx video playlist for Windows Media Center. Free WinRAR WinRAR is a powerful archive manager. It can backup your data and reduce the size of email attachments, decompress RAR, ZIP and other files downloaded from Internet and create new archives in RAR and ZIP file format. COST/Trial Available Blogging – I use the following for my blog. Name Description License Insert Code for Windows Live Writer Insert Code for Windows Live Writer will format a snippet of text in a number of programming languages such as C#, HTML, MSH, JavaScript, Visual Basic and TSQL. Free LiveWriter Included in Live Essentials, but the ultimate in Windows Blogging Free PasteAsVSCode Plug-in for Windows Live Writer that pastes clipboard content as Visual Studio code. Preserves syntax highlighting, indentation and background color. Converts RTF, outputted by Visual Studio, into HTML. Free Desktop Management – The list below represent the best in Windows Desktop Management. Name Description License 7 Stacks Allows users to have "stacks" of icons in their taskbar. Free Executor Executor is a multi purpose launcher and a more advanced and customizable version of windows run. Free Fences Fences is a program that helps you organize your desktop and can hide your icons when they are not in use. Free RocketDock Rocket Dock is a smoothly animated, alpha blended application launcher. It provides a nice clean interface to drop shortcuts on for easy access and organization. With each item completely customizable there is no end to what you can add and launch from the dock. Free WindowsTab Tabbing is an essential feature of modern web browsers. Window Tabs brings the productivity of tabbed window management to all of your desktop applications. Free

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  • C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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  • Ancillary Objects: Separate Debug ELF Files For Solaris

    - by Ali Bahrami
    We introduced a new object ELF object type in Solaris 11 Update 1 called the Ancillary Object. This posting describes them, using material originally written during their development, the PSARC arc case, and the Solaris Linker and Libraries Manual. ELF objects contain allocable sections, which are mapped into memory at runtime, and non-allocable sections, which are present in the file for use by debuggers and observability tools, but which are not mapped or used at runtime. Typically, all of these sections exist within a single object file. Ancillary objects allow them to instead go into a separate file. There are different reasons given for wanting such a feature. One can debate whether the added complexity is worth the benefit, and in most cases it is not. However, one important case stands out — customers with very large 32-bit objects who are not ready or able to make the transition to 64-bits. We have customers who build extremely large 32-bit objects. Historically, the debug sections in these objects have used the stabs format, which is limited, but relatively compact. In recent years, the industry has transitioned to the powerful but verbose DWARF standard. In some cases, the size of these debug sections is large enough to push the total object file size past the fundamental 4GB limit for 32-bit ELF object files. The best, and ultimately only, solution to overly large objects is to transition to 64-bits. However, consider environments where: Hundreds of users may be executing the code on large shared systems. (32-bits use less memory and bus bandwidth, and on sparc runs just as fast as 64-bit code otherwise). Complex finely tuned code, where the original authors may no longer be available. Critical production code, that was expensive to qualify and bring online, and which is otherwise serving its intended purpose without issue. Users in these risk adverse and/or high scale categories have good reasons to push 32-bits objects to the limit before moving on. Ancillary objects offer these users a longer runway. Design The design of ancillary objects is intended to be simple, both to help human understanding when examining elfdump output, and to lower the bar for debuggers such as dbx to support them. The primary and ancillary objects have the same set of section headers, with the same names, in the same order (i.e. each section has the same index in both files). A single added section of type SHT_SUNW_ANCILLARY is added to both objects, containing information that allows a debugger to identify and validate both files relative to each other. Given one of these files, the ancillary section allows you to identify the other. Allocable sections go in the primary object, and non-allocable ones go into the ancillary object. A small set of non-allocable objects, notably the symbol table, are copied into both objects. As noted above, most sections are only written to one of the two objects, but both objects have the same section header array. The section header in the file that does not contain the section data is tagged with the SHF_SUNW_ABSENT section header flag to indicate its placeholder status. Compiler writers and others who produce objects can set the SUNW_SHF_PRIMARY section header flag to mark non-allocable sections that should go to the primary object rather than the ancillary. If you don't request an ancillary object, the Solaris ELF format is unchanged. Users who don't use ancillary objects do not pay for the feature. This is important, because they exist to serve a small subset of our users, and must not complicate the common case. If you do request an ancillary object, the runtime behavior of the primary object will be the same as that of a normal object. There is no added runtime cost. The primary and ancillary object together represent a logical single object. This is facilitated by the use of a single set of section headers. One can easily imagine a tool that can merge a primary and ancillary object into a single file, or the reverse. (Note that although this is an interesting intellectual exercise, we don't actually supply such a tool because there's little practical benefit above and beyond using ld to create the files). Among the benefits of this approach are: There is no need for per-file symbol tables to reflect the contents of each file. The same symbol table that would be produced for a standard object can be used. The section contents are identical in either case — there is no need to alter data to accommodate multiple files. It is very easy for a debugger to adapt to these new files, and the processing involved can be encapsulated in input/output routines. Most of the existing debugger implementation applies without modification. The limit of a 4GB 32-bit output object is now raised to 4GB of code, and 4GB of debug data. There is also the future possibility (not currently supported) to support multiple ancillary objects, each of which could contain up to 4GB of additional debug data. It must be noted however that the 32-bit DWARF debug format is itself inherently 32-bit limited, as it uses 32-bit offsets between debug sections, so the ability to employ multiple ancillary object files may not turn out to be useful. Using Ancillary Objects (From the Solaris Linker and Libraries Guide) By default, objects contain both allocable and non-allocable sections. Allocable sections are the sections that contain executable code and the data needed by that code at runtime. Non-allocable sections contain supplemental information that is not required to execute an object at runtime. These sections support the operation of debuggers and other observability tools. The non-allocable sections in an object are not loaded into memory at runtime by the operating system, and so, they have no impact on memory use or other aspects of runtime performance no matter their size. For convenience, both allocable and non-allocable sections are normally maintained in the same file. However, there are situations in which it can be useful to separate these sections. To reduce the size of objects in order to improve the speed at which they can be copied across wide area networks. To support fine grained debugging of highly optimized code requires considerable debug data. In modern systems, the debugging data can easily be larger than the code it describes. The size of a 32-bit object is limited to 4 Gbytes. In very large 32-bit objects, the debug data can cause this limit to be exceeded and prevent the creation of the object. To limit the exposure of internal implementation details. Traditionally, objects have been stripped of non-allocable sections in order to address these issues. Stripping is effective, but destroys data that might be needed later. The Solaris link-editor can instead write non-allocable sections to an ancillary object. This feature is enabled with the -z ancillary command line option. $ ld ... -z ancillary[=outfile] ...By default, the ancillary file is given the same name as the primary output object, with a .anc file extension. However, a different name can be provided by providing an outfile value to the -z ancillary option. When -z ancillary is specified, the link-editor performs the following actions. All allocable sections are written to the primary object. In addition, all non-allocable sections containing one or more input sections that have the SHF_SUNW_PRIMARY section header flag set are written to the primary object. All remaining non-allocable sections are written to the ancillary object. The following non-allocable sections are written to both the primary object and ancillary object. .shstrtab The section name string table. .symtab The full non-dynamic symbol table. .symtab_shndx The symbol table extended index section associated with .symtab. .strtab The non-dynamic string table associated with .symtab. .SUNW_ancillary Contains the information required to identify the primary and ancillary objects, and to identify the object being examined. The primary object and all ancillary objects contain the same array of sections headers. Each section has the same section index in every file. Although the primary and ancillary objects all define the same section headers, the data for most sections will be written to a single file as described above. If the data for a section is not present in a given file, the SHF_SUNW_ABSENT section header flag is set, and the sh_size field is 0. This organization makes it possible to acquire a full list of section headers, a complete symbol table, and a complete list of the primary and ancillary objects from either of the primary or ancillary objects. The following example illustrates the underlying implementation of ancillary objects. An ancillary object is created by adding the -z ancillary command line option to an otherwise normal compilation. The file utility shows that the result is an executable named a.out, and an associated ancillary object named a.out.anc. $ cat hello.c #include <stdio.h> int main(int argc, char **argv) { (void) printf("hello, world\n"); return (0); } $ cc -g -zancillary hello.c $ file a.out a.out.anc a.out: ELF 32-bit LSB executable 80386 Version 1 [FPU], dynamically linked, not stripped, ancillary object a.out.anc a.out.anc: ELF 32-bit LSB ancillary 80386 Version 1, primary object a.out $ ./a.out hello worldThe resulting primary object is an ordinary executable that can be executed in the usual manner. It is no different at runtime than an executable built without the use of ancillary objects, and then stripped of non-allocable content using the strip or mcs commands. As previously described, the primary object and ancillary objects contain the same section headers. To see how this works, it is helpful to use the elfdump utility to display these section headers and compare them. The following table shows the section header information for a selection of headers from the previous link-edit example. Index Section Name Type Primary Flags Ancillary Flags Primary Size Ancillary Size 13 .text PROGBITS ALLOC EXECINSTR ALLOC EXECINSTR SUNW_ABSENT 0x131 0 20 .data PROGBITS WRITE ALLOC WRITE ALLOC SUNW_ABSENT 0x4c 0 21 .symtab SYMTAB 0 0 0x450 0x450 22 .strtab STRTAB STRINGS STRINGS 0x1ad 0x1ad 24 .debug_info PROGBITS SUNW_ABSENT 0 0 0x1a7 28 .shstrtab STRTAB STRINGS STRINGS 0x118 0x118 29 .SUNW_ancillary SUNW_ancillary 0 0 0x30 0x30 The data for most sections is only present in one of the two files, and absent from the other file. The SHF_SUNW_ABSENT section header flag is set when the data is absent. The data for allocable sections needed at runtime are found in the primary object. The data for non-allocable sections used for debugging but not needed at runtime are placed in the ancillary file. A small set of non-allocable sections are fully present in both files. These are the .SUNW_ancillary section used to relate the primary and ancillary objects together, the section name string table .shstrtab, as well as the symbol table.symtab, and its associated string table .strtab. It is possible to strip the symbol table from the primary object. A debugger that encounters an object without a symbol table can use the .SUNW_ancillary section to locate the ancillary object, and access the symbol contained within. The primary object, and all associated ancillary objects, contain a .SUNW_ancillary section that allows all the objects to be identified and related together. $ elfdump -T SUNW_ancillary a.out a.out.anc a.out: Ancillary Section: .SUNW_ancillary index tag value [0] ANC_SUNW_CHECKSUM 0x8724 [1] ANC_SUNW_MEMBER 0x1 a.out [2] ANC_SUNW_CHECKSUM 0x8724 [3] ANC_SUNW_MEMBER 0x1a3 a.out.anc [4] ANC_SUNW_CHECKSUM 0xfbe2 [5] ANC_SUNW_NULL 0 a.out.anc: Ancillary Section: .SUNW_ancillary index tag value [0] ANC_SUNW_CHECKSUM 0xfbe2 [1] ANC_SUNW_MEMBER 0x1 a.out [2] ANC_SUNW_CHECKSUM 0x8724 [3] ANC_SUNW_MEMBER 0x1a3 a.out.anc [4] ANC_SUNW_CHECKSUM 0xfbe2 [5] ANC_SUNW_NULL 0 The ancillary sections for both objects contain the same number of elements, and are identical except for the first element. Each object, starting with the primary object, is introduced with a MEMBER element that gives the file name, followed by a CHECKSUM that identifies the object. In this example, the primary object is a.out, and has a checksum of 0x8724. The ancillary object is a.out.anc, and has a checksum of 0xfbe2. The first element in a .SUNW_ancillary section, preceding the MEMBER element for the primary object, is always a CHECKSUM element, containing the checksum for the file being examined. The presence of a .SUNW_ancillary section in an object indicates that the object has associated ancillary objects. The names of the primary and all associated ancillary objects can be obtained from the ancillary section from any one of the files. It is possible to determine which file is being examined from the larger set of files by comparing the first checksum value to the checksum of each member that follows. Debugger Access and Use of Ancillary Objects Debuggers and other observability tools must merge the information found in the primary and ancillary object files in order to build a complete view of the object. This is equivalent to processing the information from a single file. This merging is simplified by the primary object and ancillary objects containing the same section headers, and a single symbol table. The following steps can be used by a debugger to assemble the information contained in these files. Starting with the primary object, or any of the ancillary objects, locate the .SUNW_ancillary section. The presence of this section identifies the object as part of an ancillary group, contains information that can be used to obtain a complete list of the files and determine which of those files is the one currently being examined. Create a section header array in memory, using the section header array from the object being examined as an initial template. Open and read each file identified by the .SUNW_ancillary section in turn. For each file, fill in the in-memory section header array with the information for each section that does not have the SHF_SUNW_ABSENT flag set. The result will be a complete in-memory copy of the section headers with pointers to the data for all sections. Once this information has been acquired, the debugger can proceed as it would in the single file case, to access and control the running program. Note - The ELF definition of ancillary objects provides for a single primary object, and an arbitrary number of ancillary objects. At this time, the Oracle Solaris link-editor only produces a single ancillary object containing all non-allocable sections. This may change in the future. Debuggers and other observability tools should be written to handle the general case of multiple ancillary objects. ELF Implementation Details (From the Solaris Linker and Libraries Guide) To implement ancillary objects, it was necessary to extend the ELF format to add a new object type (ET_SUNW_ANCILLARY), a new section type (SHT_SUNW_ANCILLARY), and 2 new section header flags (SHF_SUNW_ABSENT, SHF_SUNW_PRIMARY). In this section, I will detail these changes, in the form of diffs to the Solaris Linker and Libraries manual. Part IV ELF Application Binary Interface Chapter 13: Object File Format Object File Format Edit Note: This existing section at the beginning of the chapter describes the ELF header. There's a table of object file types, which now includes the new ET_SUNW_ANCILLARY type. e_type Identifies the object file type, as listed in the following table. NameValueMeaning ET_NONE0No file type ET_REL1Relocatable file ET_EXEC2Executable file ET_DYN3Shared object file ET_CORE4Core file ET_LOSUNW0xfefeStart operating system specific range ET_SUNW_ANCILLARY0xfefeAncillary object file ET_HISUNW0xfefdEnd operating system specific range ET_LOPROC0xff00Start processor-specific range ET_HIPROC0xffffEnd processor-specific range Sections Edit Note: This overview section defines the section header structure, and provides a high level description of known sections. It was updated to define the new SHF_SUNW_ABSENT and SHF_SUNW_PRIMARY flags and the new SHT_SUNW_ANCILLARY section. ... sh_type Categorizes the section's contents and semantics. Section types and their descriptions are listed in Table 13-5. sh_flags Sections support 1-bit flags that describe miscellaneous attributes. Flag definitions are listed in Table 13-8. ... Table 13-5 ELF Section Types, sh_type NameValue . . . SHT_LOSUNW0x6fffffee SHT_SUNW_ancillary0x6fffffee . . . ... SHT_LOSUNW - SHT_HISUNW Values in this inclusive range are reserved for Oracle Solaris OS semantics. SHT_SUNW_ANCILLARY Present when a given object is part of a group of ancillary objects. Contains information required to identify all the files that make up the group. See Ancillary Section. ... Table 13-8 ELF Section Attribute Flags NameValue . . . SHF_MASKOS0x0ff00000 SHF_SUNW_NODISCARD0x00100000 SHF_SUNW_ABSENT0x00200000 SHF_SUNW_PRIMARY0x00400000 SHF_MASKPROC0xf0000000 . . . ... SHF_SUNW_ABSENT Indicates that the data for this section is not present in this file. When ancillary objects are created, the primary object and any ancillary objects, will all have the same section header array, to facilitate merging them to form a complete view of the object, and to allow them to use the same symbol tables. Each file contains a subset of the section data. The data for allocable sections is written to the primary object while the data for non-allocable sections is written to an ancillary file. The SHF_SUNW_ABSENT flag is used to indicate that the data for the section is not present in the object being examined. When the SHF_SUNW_ABSENT flag is set, the sh_size field of the section header must be 0. An application encountering an SHF_SUNW_ABSENT section can choose to ignore the section, or to search for the section data within one of the related ancillary files. SHF_SUNW_PRIMARY The default behavior when ancillary objects are created is to write all allocable sections to the primary object and all non-allocable sections to the ancillary objects. The SHF_SUNW_PRIMARY flag overrides this behavior. Any output section containing one more input section with the SHF_SUNW_PRIMARY flag set is written to the primary object without regard for its allocable status. ... Two members in the section header, sh_link, and sh_info, hold special information, depending on section type. Table 13-9 ELF sh_link and sh_info Interpretation sh_typesh_linksh_info . . . SHT_SUNW_ANCILLARY The section header index of the associated string table. 0 . . . Special Sections Edit Note: This section describes the sections used in Solaris ELF objects, using the types defined in the previous description of section types. It was updated to define the new .SUNW_ancillary (SHT_SUNW_ANCILLARY) section. Various sections hold program and control information. Sections in the following table are used by the system and have the indicated types and attributes. Table 13-10 ELF Special Sections NameTypeAttribute . . . .SUNW_ancillarySHT_SUNW_ancillaryNone . . . ... .SUNW_ancillary Present when a given object is part of a group of ancillary objects. Contains information required to identify all the files that make up the group. See Ancillary Section for details. ... Ancillary Section Edit Note: This new section provides the format reference describing the layout of a .SUNW_ancillary section and the meaning of the various tags. Note that these sections use the same tag/value concept used for dynamic and capabilities sections, and will be familiar to anyone used to working with ELF. In addition to the primary output object, the Solaris link-editor can produce one or more ancillary objects. Ancillary objects contain non-allocable sections that would normally be written to the primary object. When ancillary objects are produced, the primary object and all of the associated ancillary objects contain a SHT_SUNW_ancillary section, containing information that identifies these related objects. Given any one object from such a group, the ancillary section provides the information needed to identify and interpret the others. This section contains an array of the following structures. See sys/elf.h. typedef struct { Elf32_Word a_tag; union { Elf32_Word a_val; Elf32_Addr a_ptr; } a_un; } Elf32_Ancillary; typedef struct { Elf64_Xword a_tag; union { Elf64_Xword a_val; Elf64_Addr a_ptr; } a_un; } Elf64_Ancillary; For each object with this type, a_tag controls the interpretation of a_un. a_val These objects represent integer values with various interpretations. a_ptr These objects represent file offsets or addresses. The following ancillary tags exist. Table 13-NEW1 ELF Ancillary Array Tags NameValuea_un ANC_SUNW_NULL0Ignored ANC_SUNW_CHECKSUM1a_val ANC_SUNW_MEMBER2a_ptr ANC_SUNW_NULL Marks the end of the ancillary section. ANC_SUNW_CHECKSUM Provides the checksum for a file in the c_val element. When ANC_SUNW_CHECKSUM precedes the first instance of ANC_SUNW_MEMBER, it provides the checksum for the object from which the ancillary section is being read. When it follows an ANC_SUNW_MEMBER tag, it provides the checksum for that member. ANC_SUNW_MEMBER Specifies an object name. The a_ptr element contains the string table offset of a null-terminated string, that provides the file name. An ancillary section must always contain an ANC_SUNW_CHECKSUM before the first instance of ANC_SUNW_MEMBER, identifying the current object. Following that, there should be an ANC_SUNW_MEMBER for each object that makes up the complete set of objects. Each ANC_SUNW_MEMBER should be followed by an ANC_SUNW_CHECKSUM for that object. A typical ancillary section will therefore be structured as: TagMeaning ANC_SUNW_CHECKSUMChecksum of this object ANC_SUNW_MEMBERName of object #1 ANC_SUNW_CHECKSUMChecksum for object #1 . . . ANC_SUNW_MEMBERName of object N ANC_SUNW_CHECKSUMChecksum for object N ANC_SUNW_NULL An object can therefore identify itself by comparing the initial ANC_SUNW_CHECKSUM to each of the ones that follow, until it finds a match. Related Other Work The GNU developers have also encountered the need/desire to support separate debug information files, and use the solution detailed at http://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html. At the current time, the separate debug file is constructed by building the standard object first, and then copying the debug data out of it in a separate post processing step, Hence, it is limited to a total of 4GB of code and debug data, just as a single object file would be. They are aware of this, and I have seen online comments indicating that they may add direct support for generating these separate files to their link-editor. It is worth noting that the GNU objcopy utility is available on Solaris, and that the Studio dbx debugger is able to use these GNU style separate debug files even on Solaris. Although this is interesting in terms giving Linux users a familiar environment on Solaris, the 4GB limit means it is not an answer to the problem of very large 32-bit objects. We have also encountered issues with objcopy not understanding Solaris-specific ELF sections, when using this approach. The GNU community also has a current effort to adapt their DWARF debug sections in order to move them to separate files before passing the relocatable objects to the linker. The details of Project Fission can be found at http://gcc.gnu.org/wiki/DebugFission. The goal of this project appears to be to reduce the amount of data seen by the link-editor. The primary effort revolves around moving DWARF data to separate .dwo files so that the link-editor never encounters them. The details of modifying the DWARF data to be usable in this form are involved — please see the above URL for details.

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  • ANTS CLR and Memory Profiler In Depth Review (Part 1 of 2 &ndash; CLR Profiler)

    - by ToStringTheory
    One of the things that people might not know about me, is my obsession to make my code as efficient as possible.  Many people might not realize how much of a task or undertaking that this might be, but it is surely a task as monumental as climbing Mount Everest, except this time it is a challenge for the mind…  In trying to make code efficient, there are many different factors that play a part – size of project or solution, tiers, language used, experience and training of the programmer, technologies used, maintainability of the code – the list can go on for quite some time. I spend quite a bit of time when developing trying to determine what is the best way to implement a feature to accomplish the efficiency that I look to achieve.  One program that I have recently come to learn about – Red Gate ANTS Performance (CLR) and Memory profiler gives me tools to accomplish that job more efficiently as well.  In this review, I am going to cover some of the features of the ANTS profiler set by compiling some hideous example code to test against. Notice As a member of the Geeks With Blogs Influencers program, one of the perks is the ability to review products, in exchange for a free license to the program.  I have not let this affect my opinions of the product in any way, and Red Gate nor Geeks With Blogs has tried to influence my opinion regarding this product in any way. Introduction The ANTS Profiler pack provided by Red Gate was something that I had not heard of before receiving an email regarding an offer to review it for a license.  Since I look to make my code efficient, it was a no brainer for me to try it out!  One thing that I have to say took me by surprise is that upon downloading the program and installing it you fill out a form for your usual contact information.  Sure enough within 2 hours, I received an email from a sales representative at Red Gate asking if she could help me to achieve the most out of my trial time so it wouldn’t go to waste.  After replying to her and explaining that I was looking to review its feature set, she put me in contact with someone that setup a demo session to give me a quick rundown of its features via an online meeting.  After having dealt with a massive ordeal with one of my utility companies and their complete lack of customer service, Red Gates friendly and helpful representatives were a breath of fresh air, and something I was thankful for. ANTS CLR Profiler The ANTS CLR profiler is the thing I want to focus on the most in this post, so I am going to dive right in now. Install was simple and took no time at all.  It installed both the profiler for the CLR and Memory, but also visual studio extensions to facilitate the usage of the profilers (click any images for full size images): The Visual Studio menu options (under ANTS menu) Starting the CLR Performance Profiler from the start menu yields this window If you follow the instructions after launching the program from the start menu (Click File > New Profiling Session to start a new project), you are given a dialog with plenty of options for profiling: The New Session dialog.  Lots of options.  One thing I noticed is that the buttons in the lower right were half-covered by the panel of the application.  If I had to guess, I would imagine that this is caused by my DPI settings being set to 125%.  This is a problem I have seen in other applications as well that don’t scale well to different dpi scales. The profiler options give you the ability to profile: .NET Executable ASP.NET web application (hosted in IIS) ASP.NET web application (hosted in IIS express) ASP.NET web application (hosted in Cassini Web Development Server) SharePoint web application (hosted in IIS) Silverlight 4+ application Windows Service COM+ server XBAP (local XAML browser application) Attach to an already running .NET 4 process Choosing each option provides a varying set of other variables/options that one can set including options such as application arguments, operating path, record I/O performance performance counters to record (43 counters in all!), etc…  All in all, they give you the ability to profile many different .Net project types, and make it simple to do so.  In most cases of my using this application, I would be using the built in Visual Studio extensions, as they automatically start a new profiling project in ANTS with the options setup, and start your program, however RedGate has made it easy enough to profile outside of Visual Studio as well. On the flip side of this, as someone who lives most of their work life in Visual Studio, one thing I do wish is that instead of opening an entirely separate application/gui to perform profiling after launching, that instead they would provide a Visual Studio panel with the information, and integrate more of the profiling project information into Visual Studio.  So, now that we have an idea of what options that the profiler gives us, its time to test its abilities and features. Horrendous Example Code – Prime Number Generator One of my interests besides development, is Physics and Math – what I went to college for.  I have especially always been interested in prime numbers, as they are something of a mystery…  So, I decided that I would go ahead and to test the abilities of the profiler, I would write a small program, website, and library to generate prime numbers in the quantity that you ask for.  I am going to start off with some terrible code, and show how I would see the profiler being used as a development tool. First off, the IPrimes interface (all code is downloadable at the end of the post): interface IPrimes { IEnumerable<int> GetPrimes(int retrieve); } Simple enough, right?  Anything that implements the interface will (hopefully) provide an IEnumerable of int, with the quantity specified in the parameter argument.  Next, I am going to implement this interface in the most basic way: public class DumbPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _analyzing = 4; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; //start dividing at 2 //divide until number is reached, or determined not prime for (int i = 2; i < _analyzing && isPrime; i++) { //if (i) goes into _analyzing without a remainder, //_analyzing is NOT prime if (_analyzing % i == 0) isPrime = false; } //if it is prime, add to found list if (isPrime) _foundPrimes.Add(_analyzing); //increment number to analyze next _analyzing++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } This is the simplest way to get primes in my opinion.  Checking each number by the straight definition of a prime – is it divisible by anything besides 1 and itself. I have included this code in a base class library for my solution, as I am going to use it to demonstrate a couple of features of ANTS.  This class library is consumed by a simple non-MVVM WPF application, and a simple MVC4 website.  I will not post the WPF code here inline, as it is simply an ObservableCollection<int>, a label, two textbox’s, and a button. Starting a new Profiling Session So, in Visual Studio, I have just completed my first stint developing the GUI and DumbPrimes IPrimes class, so now I want to check my codes efficiency by profiling it.  All I have to do is build the solution (surprised initiating a profiling session doesn’t do this, but I suppose I can understand it), and then click the ANTS menu, followed by Profile Performance.  I am then greeted by the profiler starting up and already monitoring my program live: You are provided with a realtime graph at the top, and a pane at the bottom giving you information on how to proceed.  I am going to start by asking my program to show me the first 15000 primes: After the program finally began responding again (I did all the work on the main UI thread – how bad!), I stopped the profiler, which did kill the process of my program too.  One important thing to note, is that the profiler by default wants to give you a lot of detail about the operation – line hit counts, time per line, percent time per line, etc…  The important thing to remember is that this itself takes a lot of time.  When running my program without the profiler attached, it can generate the 15000 primes in 5.18 seconds, compared to 74.5 seconds – almost a 1500 percent increase.  While this may seem like a lot, remember that there is a trade off.  It may be WAY more inefficient, however, I am able to drill down and make improvements to specific problem areas, and then decrease execution time all around. Analyzing the Profiling Session After clicking ‘Stop Profiling’, the process running my application stopped, and the entire execution time was automatically selected by ANTS, and the results shown below: Now there are a number of interesting things going on here, I am going to cover each in a section of its own: Real Time Performance Counter Bar (top of screen) At the top of the screen, is the real time performance bar.  As your application is running, this will constantly update with the currently selected performance counters status.  A couple of cool things to note are the fact that you can drag a selection around specific time periods to drill down the detail views in the lower 2 panels to information pertaining to only that period. After selecting a time period, you can bookmark a section and name it, so that it is easy to find later, or after reloaded at a later time.  You can also zoom in, out, or fit the graph to the space provided – useful for drilling down. It may be hard to see, but at the top of the processor time graph below the time ticks, but above the red usage graph, there is a green bar. This bar shows at what times a method that is selected in the ‘Call tree’ panel is called. Very cool to be able to click on a method and see at what times it made an impact. As I said before, ANTS provides 43 different performance counters you can hook into.  Click the arrow next to the Performance tab at the top will allow you to change between different counters if you have them selected: Method Call Tree, ADO.Net Database Calls, File IO – Detail Panel Red Gate really hit the mark here I think. When you select a section of the run with the graph, the call tree populates to fill a hierarchical tree of method calls, with information regarding each of the methods.   By default, methods are hidden where the source is not provided (framework type code), however, Red Gate has integrated Reflector into ANTS, so even if you don’t have source for something, you can select a method and get the source if you want.  Methods are also hidden where the impact is seen as insignificant – methods that are only executed for 1% of the time of the overall calling methods time; in other words, working on making them better is not where your efforts should be focused. – Smart! Source Panel – Detail Panel The source panel is where you can see line level information on your code, showing the code for the currently selected method from the Method Call Tree.  If the code is not available, Reflector takes care of it and shows the code anyways! As you can notice, there does seem to be a problem with how ANTS determines what line is the actual line that a call is completed on.  I have suspicions that this may be due to some of the inline code optimizations that the CLR applies upon compilation of the assembly.  In a method with comments, the problem is much more severe: As you can see here, apparently the most offending code in my base library was a comment – *gasp*!  Removing the comments does help quite a bit, however I hope that Red Gate works on their counter algorithm soon to improve the logic on positioning for statistics: I did a small test just to demonstrate the lines are correct without comments. For me, it isn’t a deal breaker, as I can usually determine the correct placements by looking at the application code in the region and determining what makes sense, but it is something that would probably build up some irritation with time. Feature – Suggest Method for Optimization A neat feature to really help those in need of a pointer, is the menu option under tools to automatically suggest methods to optimize/improve: Nice feature – clicking it filters the call tree and stars methods that it thinks are good candidates for optimization.  I do wish that they would have made it more visible for those of use who aren’t great on sight: Process Integration I do think that this could have a place in my process.  After experimenting with the profiler, I do think it would be a great benefit to do some development, testing, and then after all the bugs are worked out, use the profiler to check on things to make sure nothing seems like it is hogging more than its fair share.  For example, with this program, I would have developed it, ran it, tested it – it works, but slowly. After looking at the profiler, and seeing the massive amount of time spent in 1 method, I might go ahead and try to re-implement IPrimes (I actually would probably rewrite the offending code, but so that I can distribute both sets of code easily, I’m just going to make another implementation of IPrimes).  Using two pieces of knowledge about prime numbers can make this method MUCH more efficient – prime numbers fall into two buckets 6k+/-1 , and a number is prime if it is not divisible by any other primes before it: public class SmartPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _k = 1; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; int potentialPrime; //analyze 6k-1 //assign the value to potential potentialPrime = 6 * _k - 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); if (_foundPrimes.Count() == retrieve) break; //analyze 6k+1 //assign the value to potential potentialPrime = 6 * _k + 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); //increment k to analyze next _k++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } Now there are definitely more things I can do to help make this more efficient, but for the scope of this example, I think this is fine (but still hideous)! Profiling this now yields a happy surprise 27 seconds to generate the 15000 primes with the profiler attached, and only 1.43 seconds without.  One important thing I wanted to call out though was the performance graph now: Notice anything odd?  The %Processor time is above 100%.  This is because there is now more than 1 core in the operation.  A better label for the chart in my mind would have been %Core time, but to each their own. Another odd thing I noticed was that the profiler seemed to be spot on this time in my DumbPrimes class with line details in source, even with comments..  Odd. Profiling Web Applications The last thing that I wanted to cover, that means a lot to me as a web developer, is the great amount of work that Red Gate put into the profiler when profiling web applications.  In my solution, I have a simple MVC4 application setup with 1 page, a single input form, that will output prime values as my WPF app did.  Launching the profiler from Visual Studio as before, nothing is really different in the profiler window, however I did receive a UAC prompt for a Red Gate helper app to integrate with the web server without notification. After requesting 500, 1000, 2000, and 5000 primes, and looking at the profiler session, things are slightly different from before: As you can see, there are 4 spikes of activity in the processor time graph, but there is also something new in the call tree: That’s right – ANTS will actually group method calls by get/post operations, so it is easier to find out what action/page is giving the largest problems…  Pretty cool in my mind! Overview Overall, I think that Red Gate ANTS CLR Profiler has a lot to offer, however I think it also has a long ways to go.  3 Biggest Pros: Ability to easily drill down from time graph, to method calls, to source code Wide variety of counters to choose from when profiling your application Excellent integration/grouping of methods being called from web applications by request – BRILLIANT! 3 Biggest Cons: Issue regarding line details in source view Nit pick – Processor time vs. Core time Nit pick – Lack of full integration with Visual Studio Ratings Ease of Use (7/10) – I marked down here because of the problems with the line level details and the extra work that that entails, and the lack of better integration with Visual Studio. Effectiveness (10/10) – I believe that the profiler does EXACTLY what it purports to do.  Especially with its large variety of performance counters, a definite plus! Features (9/10) – Besides the real time performance monitoring, and the drill downs that I’ve shown here, ANTS also has great integration with ADO.Net, with the ability to show database queries run by your application in the profiler.  This, with the line level details, the web request grouping, reflector integration, and various options to customize your profiling session I think create a great set of features! Customer Service (10/10) – My entire experience with Red Gate personnel has been nothing but good.  their people are friendly, helpful, and happy! UI / UX (8/10) – The interface is very easy to get around, and all of the options are easy to find.  With a little bit of poking around, you’ll be optimizing Hello World in no time flat! Overall (8/10) – Overall, I am happy with the Performance Profiler and its features, as well as with the service I received when working with the Red Gate personnel.  I WOULD recommend you trying the application and seeing if it would fit into your process, BUT, remember there are still some kinks in it to hopefully be worked out. My next post will definitely be shorter (hopefully), but thank you for reading up to here, or skipping ahead!  Please, if you do try the product, drop me a message and let me know what you think!  I would love to hear any opinions you may have on the product. Code Feel free to download the code I used above – download via DropBox

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  • Towards Database Continuous Delivery – What Next after Continuous Integration? A Checklist

    - by Ben Rees
    .dbd-banner p{ font-size:0.75em; padding:0 0 10px; margin:0 } .dbd-banner p span{ color:#675C6D; } .dbd-banner p:last-child{ padding:0; } @media ALL and (max-width:640px){ .dbd-banner{ background:#f0f0f0; padding:5px; color:#333; margin-top: 5px; } } -- Database delivery patterns & practices STAGE 4 AUTOMATED DEPLOYMENT If you’ve been fortunate enough to get to the stage where you’ve implemented some sort of continuous integration process for your database updates, then hopefully you’re seeing the benefits of that investment – constant feedback on changes your devs are making, advanced warning of data loss (prior to the production release on Saturday night!), a nice suite of automated tests to check business logic, so you know it’s going to work when it goes live, and so on. But what next? What can you do to improve your delivery process further, moving towards a full continuous delivery process for your database? In this article I describe some of the issues you might need to tackle on the next stage of this journey, and how to plan to overcome those obstacles before they appear. Our Database Delivery Learning Program consists of four stages, really three – source controlling a database, running continuous integration processes, then how to set up automated deployment (the middle stage is split in two – basic and advanced continuous integration, making four stages in total). If you’ve managed to work through the first three of these stages – source control, basic, then advanced CI, then you should have a solid change management process set up where, every time one of your team checks in a change to your database (whether schema or static reference data), this change gets fully tested automatically by your CI server. But this is only part of the story. Great, we know that our updates work, that the upgrade process works, that the upgrade isn’t going to wipe our 4Tb of production data with a single DROP TABLE. But – how do you get this (fully tested) release live? Continuous delivery means being always ready to release your software at any point in time. There’s a significant gap between your latest version being tested, and it being easily releasable. Just a quick note on terminology – there’s a nice piece here from Atlassian on the difference between continuous integration, continuous delivery and continuous deployment. This piece also gives a nice description of the benefits of continuous delivery. These benefits have been summed up by Jez Humble at Thoughtworks as: “Continuous delivery is a set of principles and practices to reduce the cost, time, and risk of delivering incremental changes to users” There’s another really useful piece here on Simple-Talk about the need for continuous delivery and how it applies to the database written by Phil Factor – specifically the extra needs and complexities of implementing a full CD solution for the database (compared to just implementing CD for, say, a web app). So, hopefully you’re convinced of moving on the the next stage! The next step after CI is to get some sort of automated deployment (or “release management”) process set up. But what should I do next? What do I need to plan and think about for getting my automated database deployment process set up? Can’t I just install one of the many release management tools available and hey presto, I’m ready! If only it were that simple. Below I list some of the areas that it’s worth spending a little time on, where a little planning and prep could go a long way. It’s also worth pointing out, that this should really be an evolving process. Depending on your starting point of course, it can be a long journey from your current setup to a full continuous delivery pipeline. If you’ve got a CI mechanism in place, you’re certainly a long way down that path. Nevertheless, we’d recommend evolving your process incrementally. Pages 157 and 129-141 of the book on Continuous Delivery (by Jez Humble and Dave Farley) have some great guidance on building up a pipeline incrementally: http://www.amazon.com/Continuous-Delivery-Deployment-Automation-Addison-Wesley/dp/0321601912 For now, in this post, we’ll look at the following areas for your checklist: You and Your Team Environments The Deployment Process Rollback and Recovery Development Practices You and Your Team It’s a cliché in the DevOps community that “It’s not all about processes and tools, really it’s all about a culture”. As stated in this DevOps report from Puppet Labs: “DevOps processes and tooling contribute to high performance, but these practices alone aren’t enough to achieve organizational success. The most common barriers to DevOps adoption are cultural: lack of manager or team buy-in, or the value of DevOps isn’t understood outside of a specific group”. Like most clichés, there’s truth in there – if you want to set up a database continuous delivery process, you need to get your boss, your department, your company (if relevant) onside. Why? Because it’s an investment with the benefits coming way down the line. But the benefits are huge – for HP, in the book A Practical Approach to Large-Scale Agile Development: How HP Transformed LaserJet FutureSmart Firmware, these are summarized as: -2008 to present: overall development costs reduced by 40% -Number of programs under development increased by 140% -Development costs per program down 78% -Firmware resources now driving innovation increased by a factor of 8 (from 5% working on new features to 40% But what does this mean? It means that, when moving to the next stage, to make that extra investment in automating your deployment process, it helps a lot if everyone is convinced that this is a good thing. That they understand the benefits of automated deployment and are willing to make the effort to transform to a new way of working. Incidentally, if you’re ever struggling to convince someone of the value I’d strongly recommend just buying them a copy of this book – a great read, and a very practical guide to how it can really work at a large org. I’ve spoken to many customers who have implemented database CI who describe their deployment process as “The point where automation breaks down. Up to that point, the CI process runs, untouched by human hand, but as soon as that’s finished we revert to manual.” This deployment process can involve, for example, a DBA manually comparing an environment (say, QA) to production, creating the upgrade scripts, reading through them, checking them against an Excel document emailed to him/her the night before, turning to page 29 in his/her notebook to double-check how replication is switched off and on for deployments, and so on and so on. Painful, error-prone and lengthy. But the point is, if this is something like your deployment process, telling your DBA “We’re changing everything you do and your toolset next week, to automate most of your role – that’s okay isn’t it?” isn’t likely to go down well. There’s some work here to bring him/her onside – to explain what you’re doing, why there will still be control of the deployment process and so on. Or of course, if you’re the DBA looking after this process, you have to do a similar job in reverse. You may have researched and worked out how you’d like to change your methodology to start automating your painful release process, but do the dev team know this? What if they have to start producing different artifacts for you? Will they be happy with this? Worth talking to them, to find out. As well as talking to your DBA/dev team, the other group to get involved before implementation is your manager. And possibly your manager’s manager too. As mentioned, unless there’s buy-in “from the top”, you’re going to hit problems when the implementation starts to get rocky (and what tool/process implementations don’t get rocky?!). You need to have support from someone senior in your organisation – someone you can turn to when you need help with a delayed implementation, lack of resources or lack of progress. Actions: Get your DBA involved (or whoever looks after live deployments) and discuss what you’re planning to do or, if you’re the DBA yourself, get the dev team up-to-speed with your plans, Get your boss involved too and make sure he/she is bought in to the investment. Environments Where are you going to deploy to? And really this question is – what environments do you want set up for your deployment pipeline? Assume everyone has “Production”, but do you have a QA environment? Dedicated development environments for each dev? Proper pre-production? I’ve seen every setup under the sun, and there is often a big difference between “What we want, to do continuous delivery properly” and “What we’re currently stuck with”. Some of these differences are: What we want What we’ve got Each developer with their own dedicated database environment A single shared “development” environment, used by everyone at once An Integration box used to test the integration of all check-ins via the CI process, along with a full suite of unit-tests running on that machine In fact if you have a CI process running, you’re likely to have some sort of integration server running (even if you don’t call it that!). Whether you have a full suite of unit tests running is a different question… Separate QA environment used explicitly for manual testing prior to release “We just test on the dev environments, or maybe pre-production” A proper pre-production (or “staging”) box that matches production as closely as possible Hopefully a pre-production box of some sort. But does it match production closely!? A production environment reproducible from source control A production box which has drifted significantly from anything in source control The big question is – how much time and effort are you going to invest in fixing these issues? In reality this just involves figuring out which new databases you’re going to create and where they’ll be hosted – VMs? Cloud-based? What about size/data issues – what data are you going to include on dev environments? Does it need to be masked to protect access to production data? And often the amount of work here really depends on whether you’re working on a new, greenfield project, or trying to update an existing, brownfield application. There’s a world if difference between starting from scratch with 4 or 5 clean environments (reproducible from source control of course!), and trying to re-purpose and tweak a set of existing databases, with all of their surrounding processes and quirks. But for a proper release management process, ideally you have: Dedicated development databases, An Integration server used for testing continuous integration and running unit tests. [NB: This is the point at which deployments are automatic, without human intervention. Each deployment after this point is a one-click (but human) action], QA – QA engineers use a one-click deployment process to automatically* deploy chosen releases to QA for testing, Pre-production. The environment you use to test the production release process, Production. * A note on the use of the word “automatic” – when carrying out automated deployments this does not mean that the deployment is happening without human intervention (i.e. that something is just deploying over and over again). It means that the process of carrying out the deployment is automatic in that it’s not a person manually running through a checklist or set of actions. The deployment still requires a single-click from a user. Actions: Get your environments set up and ready, Set access permissions appropriately, Make sure everyone understands what the environments will be used for (it’s not a “free-for-all” with all environments to be accessed, played with and changed by development). The Deployment Process As described earlier, most existing database deployment processes are pretty manual. The following is a description of a process we hear very often when we ask customers “How do your database changes get live? How does your manual process work?” Check pre-production matches production (use a schema compare tool, like SQL Compare). Sometimes done by taking a backup from production and restoring in to pre-prod, Again, use a schema compare tool to find the differences between the latest version of the database ready to go live (i.e. what the team have been developing). This generates a script, User (generally, the DBA), reviews the script. This often involves manually checking updates against a spreadsheet or similar, Run the script on pre-production, and check there are no errors (i.e. it upgrades pre-production to what you hoped), If all working, run the script on production.* * this assumes there’s no problem with production drifting away from pre-production in the interim time period (i.e. someone has hacked something in to the production box without going through the proper change management process). This difference could undermine the validity of your pre-production deployment test. Red Gate is currently working on a free tool to detect this problem – sign up here at www.sqllighthouse.com, if you’re interested in testing early versions. There are several variations on this process – some better, some much worse! How do you automate this? In particular, step 3 – surely you can’t automate a DBA checking through a script, that everything is in order!? The key point here is to plan what you want in your new deployment process. There are so many options. At one extreme, pure continuous deployment – whenever a dev checks something in to source control, the CI process runs (including extensive and thorough testing!), before the deployment process keys in and automatically deploys that change to the live box. Not for the faint hearted – and really not something we recommend. At the other extreme, you might be more comfortable with a semi-automated process – the pre-production/production matching process is automated (with an error thrown if these environments don’t match), followed by a manual intervention, allowing for script approval by the DBA. One he/she clicks “Okay, I’m happy for that to go live”, the latter stages automatically take the script through to live. And anything in between of course – and other variations. But we’d strongly recommended sitting down with a whiteboard and your team, and spending a couple of hours mapping out “What do we do now?”, “What do we actually want?”, “What will satisfy our needs for continuous delivery, but still maintaining some sort of continuous control over the process?” NB: Most of what we’re discussing here is about production deployments. It’s important to note that you will also need to map out a deployment process for earlier environments (for example QA). However, these are likely to be less onerous, and many customers opt for a much more automated process for these boxes. Actions: Sit down with your team and a whiteboard, and draw out the answers to the questions above for your production deployments – “What do we do now?”, “What do we actually want?”, “What will satisfy our needs for continuous delivery, but still maintaining some sort of continuous control over the process?” Repeat for earlier environments (QA and so on). Rollback and Recovery If only every deployment went according to plan! Unfortunately they don’t – and when things go wrong, you need a rollback or recovery plan for what you’re going to do in that situation. Once you move in to a more automated database deployment process, you’re far more likely to be deploying more frequently than before. No longer once every 6 months, maybe now once per week, or even daily. Hence the need for a quick rollback or recovery process becomes paramount, and should be planned for. NB: These are mainly scenarios for handling rollbacks after the transaction has been committed. If a failure is detected during the transaction, the whole transaction can just be rolled back, no problem. There are various options, which we’ll explore in subsequent articles, things like: Immediately restore from backup, Have a pre-tested rollback script (remembering that really this is a “roll-forward” script – there’s not really such a thing as a rollback script for a database!) Have fallback environments – for example, using a blue-green deployment pattern. Different options have pros and cons – some are easier to set up, some require more investment in infrastructure; and of course some work better than others (the key issue with using backups, is loss of the interim transaction data that has been added between the failed deployment and the restore). The best mechanism will be primarily dependent on how your application works and how much you need a cast-iron failsafe mechanism. Actions: Work out an appropriate rollback strategy based on how your application and business works, your appetite for investment and requirements for a completely failsafe process. Development Practices This is perhaps the more difficult area for people to tackle. The process by which you can deploy database updates is actually intrinsically linked with the patterns and practices used to develop that database and linked application. So you need to decide whether you want to implement some changes to the way your developers actually develop the database (particularly schema changes) to make the deployment process easier. A good example is the pattern “Branch by abstraction”. Explained nicely here, by Martin Fowler, this is a process that can be used to make significant database changes (e.g. splitting a table) in a step-wise manner so that you can always roll back, without data loss – by making incremental updates to the database backward compatible. Slides 103-108 of the following slidedeck, from Niek Bartholomeus explain the process: https://speakerdeck.com/niekbartho/orchestration-in-meatspace As these slides show, by making a significant schema change in multiple steps – where each step can be rolled back without any loss of new data – this affords the release team the opportunity to have zero-downtime deployments with considerably less stress (because if an increment goes wrong, they can roll back easily). There are plenty more great patterns that can be implemented – the book Refactoring Databases, by Scott Ambler and Pramod Sadalage is a great read, if this is a direction you want to go in: http://www.amazon.com/Refactoring-Databases-Evolutionary-paperback-Addison-Wesley/dp/0321774515 But the question is – how much of this investment are you willing to make? How often are you making significant schema changes that would require these best practices? Again, there’s a difference here between migrating old projects and starting afresh – with the latter it’s much easier to instigate best practice from the start. Actions: For your business, work out how far down the path you want to go, amending your database development patterns to “best practice”. It’s a trade-off between implementing quality processes, and the necessity to do so (depending on how often you make complex changes). Socialise these changes with your development group. No-one likes having “best practice” changes imposed on them, so good to introduce these ideas and the rationale behind them early.   Summary The next stages of implementing a continuous delivery pipeline for your database changes (once you have CI up and running) require a little pre-planning, if you want to get the most out of the work, and for the implementation to go smoothly. We’ve covered some of the checklist of areas to consider – mainly in the areas of “Getting the team ready for the changes that are coming” and “Planning our your pipeline, environments, patterns and practices for development”, though there will be more detail, depending on where you’re coming from – and where you want to get to. This article is part of our database delivery patterns & practices series on Simple Talk. Find more articles for version control, automated testing, continuous integration & deployment.

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  • WCF service hosted in IIS7 with administrator rights?

    - by Allan Baker
    Hello, How do I grant administrator rights to a running WCF service hosted in IIS7? The problem is, my code works fine in a test console application runned as an administrator, but the same code used from WCF service in IIS7 fails. When I run the same console test application without admin rights, code fails. So, how do I grant admin rights to a WCF service hosted in IIS7? Do I grant admin rights to IIS7 service? Can I grant rights to a specific WCF service? How do I do 'Run as an administrator' on IIS7 or specific website? Thanks! (That's the question, here is a more detailed description of a situation: I am trying to capture frames from a webcam into a jpg file using Touchless library, and I can do that from a console application with admin rights. When I run that same console app without admin rights I cannot access a webcam in code. Same thing happens in a WCF service with the same code.)

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  • Multi Svn Repositories in Apache

    - by fampinheiro
    I have a set up with apache and subversion In the apache configuration i have <Location /svn> DAV svn SVNParentPath c:/svn </Location> Now i have multiple repositories a a_b a_c a_b_c a_b_d b and i want to map them as a/svn a/b/svn a/c/svn a/b/c/svn a/b/d/svn b/svn to do this without adding directives and restarting apache i tought of making this rules RewriteEngine On RewriteCond $1 !=svn RewriteCond $2 !=svn RewriteRule ^/([^/]+)/(.*?)/svn/(.*)$ /$1_$2/svn/$3 [N] RewriteRule ^/([^/]+)/svn/(.*)$ /svn/$1/$2 [L,PT] this way i rewrite them to /svn/a /svn/a_b /svn/a_c /svn/a_b_c /svn/a_b_d /svn/b The objective is that the client don't have the notion of this happening when a acess is made to a folder without trailing slash the mod dav return a redirect to the folder with the trailing slash exposing my internal url. can i rewrite the outgoing url ?!

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  • HP D530 Startup Error: 512 - Chassis Fan Not Detected

    - by lyrikles
    I'm using the HP D530 Motherboard/CPU that I installed in a new case with a 600W PSU. There was a problem with the onboard chassis fan connector (3-wire) not supplying sufficient power to the chassis fan indicated by the fan spinning very slowly, but I never experienced the "512 Error" at boot. Also, the same fan works perfectly connected directly to the PSU. I disconnected it since I already have plenty of fans connected via the PSU directly. Since then, on startup, I get the error: "512 - Chassis Fan Not Detected" and am asked to "Press F1 to continue". This gets quite annoying since I use this machine remotely (w/ FreeNAS). What could be causing the onboard fan connector to not be giving enough power? If this is unable to be corrected, how can I make the BIOS think there's a chassis fan plugged in without actually plugging a fan into the onboard connector? Would it be possible to jumper the pins without damaging the motherboard or PSU? Thanks,Erik

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  • VMWare workstation: from command line, how to start a VM in service mode (run in background)?

    - by GenEric35
    Hi, I have tried the vmrun and vmware.exe executables, but both of them start the vmware GUI when starting the VM. What I want to do is start the VM without starting the VMWare GUI. The reason I am doing this is after a few hours of idle, the guest OS becomes sluggish. It has lots of RAM but the only way I found to keep it's responsiveness optimal is to shutdown(dumps the memory) and the start; a restart of the guest OS doesnt dump the memory so I need to be able to do a stop of the VM, and then a start. So far the command I use are: C:\Program Files (x86)\VMware\VMware Workstationvmrun stop F:\VirtualMachines\R2\R2.vmx C:\Program Files (x86)\VMware\VMware Workstationvmrun start F:\VirtualMachines\R2\R2.vmx But the start command actually starts the VMWare Workstation GUI, which I don't need. I'm looking for a solution to start the VM without the VMWare Wokstation GUI, or a solution to what is causing the VM to become sluggish after a few hours of running idle.

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  • Any problems usinga GoDaddy SSL certificate on a Cisco ASA firewall?

    - by Richard West
    I need to purchase and install a SSL certificate on my Cisco ASA firewall. This will allow my VPN users to connect to my ASA without receiving the certificate error from the untrusted self assigned SSL certificate that is currently on the ASA. I had good experiences with the SSL certificates that GoDaddy sells. However, I'm concerned about using them. On my web servers I have to also install GoDaddy's "intermediate certificate bundle". On the ASA I do not think that I will be able to preform anything like this. I do not fully understand what the "intermediate certificate bundle" does, but obviously it's important. So my question is can I use a GoDaddy SSL certificate on an ASA without my users getting any type of warning or error about connecting to a site that using an untrusted SSL certificate. I need this to be as simple as possible for my end users and warning messages are always scary :) Thanks!

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  • Execute a remote command after sudo - su anotheruser in Rundeck

    - by Bera
    I'm new with Rundeck and completely amazed with it and I'm trying to execute a job and my scenario is detailed below: Rundeck is configured with ssh passwordless authentication for user master between node Server (rundeck server) and node Target (remote Solaris host) for user "master" In node Target I want to execute a script /app/acme/stopApp.sh with a user appmanager Normally and manually, when I need to run script above I proceed with ssh master@server sudo su - appmanager or simply ssh -t master@server 'sudo su - appmanager' works without password and finally run (as appmanager) /app/acme/stopApp.sh But I'm not sure how can I reproduce these steps using Rundeck. I read in some previous messages that for each job line rundeck use a new ssh connection, so the workflow below always fails for me with the messages: sudo: no tty present and no askpass program specified Remote command failed with exit status 1 Please someone could help me with some information to solve this issue. Without this functionality I wouldn't be able to introduce a little DevOps in my department. I read the user guide and admin guide but I couldn't find an easy example, neither in this forum, to follow.

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  • Windows 7 Backup Disk Full

    - by George
    What happens when a Windows 7 backup disk is full? I've been trying to find documentation on the issue without success. Does Windows 7 automatically delete the oldest backup files to free up space or does it force you manually pick and choose which files to delete? Time Machine automatically deletes the oldest copy of files, but as far as I can tell Windows 7 makes you manually choose. I keep getting a running out of disk space for backup notice on Windows 7 without any option to not warn me and just delete the oldest files automatically...

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  • Do I need VMWare vSphere?

    - by Gk
    I'm planning use vmware to upgrade some of very aged server instead replace with all new bunch of server. VMWare vSphere sounds great but because of low budget I can't afford for both licenses and SANs. Without SAN, is vSphere worth the price? As I know without SAN, the VMWare HA, VMontion, FT is unavailable. So, do I need vSphere or only ESXi free version assume that I only need backup vm daily? Do you know any completed solution about backup on ESXi 4? TIA, -Gk

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  • Custom forms in Sharepoint with MS SQL Server as Backend. Is it possible?

    - by Kaan
    We're evaluating using SharePoint 2010 as our project management tool. Specifically, the system needs to satisfy the following: Discussion groups Project management (simple issue tracking, no complex workflows or vcs integrations) News feed for the project(s) File sharing based on authorization/user-roles Custom homepage Custom forms using MS SQL Server as a backend and contents of old forms searchable from the user interface. Now, I think [1-5] is possible using SharePoint (Comments are always welcome :)). I'm not sure about [6]. Is it possible? For instance, can an admin or a user of the SharePoint portal, create a custom form (without any programming) that uses MS SQL Server as a backend and publish it to the portal so that other users can also perform data entry? If it can be done (be it with or without some programming), can users perform text search on form data using the SharePoint interface?

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  • Unknown and strange RDP successful logins in EventViewer

    - by Yousef
    I have a Windows Server 2008 R2 with a valid IP, and recently I've found hundreds of unknown and strange RDP successful logins logged in EventViewer. Here are some details: They are not similar to normal logins, they happen like every second in a while even when I myself am logged in to the server. Event reads "Remote Desktop Services: User authentication succeeded" in "Microsoft-Windows-TerminalServices-RemoteConnectionManager/Operational", Event ID 1149 They seem to use some random user accounts without a domain name. I'm pretty sure that I don't have those local user accounts, and the server doesn't belong to any domain. Legitimate RDP logins have a valid user account and workgroup name, but those logins use unknown user names without any workgroup. Support staff couldn't help me and I'm very curious what are these strange logins. Are they some sort of brute force attack? so why does it read "Successful"? Am I being hacked? Why do they keep happening continually?

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  • Permission denied when using mv in Windows 7 Cygwin

    - by Michael Butler
    I have Cygwin installed on Windows 7 in a windows domain sign-on environment. I can run most typical commands without issue, but I cannot for the life of me use the "mv" command to move or rename files, regardless of the file or directory. I can copy and create files without issue. +-[12:27:57]-[mbutl2@MYHOSTNAME] +--> tmp $ >> pwd /tmp +-[12:27:58]-[mbutl2@MYHOSTNAME] +--> tmp $ >> touch test.txt +-[12:28:02]-[mbutl2@MYHOSTNAME] +--> tmp $ >> mv test.txt hello -bash: /usr/bin/mv: Permission denied I have already tried running Cygwin terminal as Administrator and the problem is the same. I'm open to workarounds, such as trying another exe for moving files and redirecting the mv command to it. Moving files works in the Windows Command Prompt.

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  • NFS and KVM. Slow Speed

    - by Javier Martinez
    I have a KVM virtualization in Debian with 2 guests (Debian and Windows 2008). I want to have a 'mount point' shared that can be accessed by the 3 system (host and 2 guests) at the same time. So the only thing that I found was a NFS/SMB network storage. I picked NFS Due to my Ethernet network (10/100), the speed average that I get between accessing/transfering files between the 3 system is always 8~10MB/s. The point is if is there any chance of get a boost system for sharing files between 3 system (at the same time) without wasting the speed of my SATA disks. I mean, without the Ethernet limitation of 10 MB/s

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  • Enable SMB file sharing on OS X - "Incorrect Password"

    - by Tim Robinson
    I have a Mac running Snow Leopard connected to an Active Directory domain. I can share folders on the Mac and view files from Windows without problems. When I try to enable my Mac account for write access through System Preferences, I'm prompted for my account's password. Even though I'm entering the right one, I get an "Incorrect Password" response. The same process works fine for the local Mac administrator account; it's the Active Directory account I'm having problems with. I followed the advice on this page on apple.com without success: (I used the Mac to reset my domain password, and re-created my login keychain) If you want to use a user account that existed before you installed Mac OS X 10.3 (Panther), you may need to reset the password for the account using Accounts preferences. Can anyone suggest what might be wrong? Until I fix this I can't write to my Mac file share from Windows.

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  • Jobs stuck in Print Queue on print server

    - by Carl
    Hello, I have a Server 2003 machine acting as a print server for about 20 printers. There is 1 printer which we are having issues with and it has 104 documents in its queue. I have attempted the "Cancel All Documents" and tried to manually cancel individual documents without success. The print jobs state "Deleting - Sent to printer" under their status. It has been in this state for about 2 hours. I do not believe restarting the spool is an option without effecting the other printers and we have Hold printer for a specific non windows printing friendly application, in which I can not loose the jobs for. Any ideas on a fix? Thanks, Carl

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  • No apache MPM package installed error

    - by Sejanus
    I'm getting "No apache MPM package installed" when trying to configure virtual hosts on apache2.2. I compiled apache2.2 from source and I did not use --with-mpm=NAME option. I thought it will compile with default one then. So the question is, is there any way to check if MPM is installed indeed and I only need to enable it somewhere? If it is not, is there any way to add it without recompiling apache? Or, is there any way to have virtual hosts without it at all? I was doing vhost configuration as per this example. Thanks in advance for your help ;) EDIT: prefork is installed. The question is, why after a2ensite / a2dissite and /etc/init.d/apache2 reload I still get error "No MPM package installed"...

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  • Can we have Linked Servers when using NTLM?

    - by BlueRaja
    I don't have access to the Active Directory settings, nor do I have access to change anything on the linked server. From everything I've read, it seems like this means I cannot use Kerberos - which is a big problem, because I don't know how to use a linked server without it. Is there any way to connect to a linked server without Kerberos? Exact problem description When I connect to the linked server while sitting in front of my server, it works fine; but when I try to connect to the linked server from any other computer (delegating through my server), it gives the error: Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'. (Microsoft SQL Server, Error: 18456) It seems that this is the "double-hop problem," and the usual solution is to enable Kerberos, which requires access to AD and the linked server. I get the same error when I set security to "Be made using the login's current security context," and I can't use "Be made using this security context" because that appears to use SQL-authentication (which is not enabled on the linked server) instead of NTLM

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