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  • Operation is not valid due to the current state of the object?

    - by Bill
    I am programming in C#; the code was working about a week ago, however it throws an exception and I don't understand at all what could be wrong with it. Var root = new CalculationNode(); -> Throw exception. In the call stack thats the only thing listed, I've been told that it could be that I need a clean build, but I am open to any ideas or suggestions. Thanks, -Bill Update: Exception's Detail System.InvalidOperationException was unhandled by user code Message=Operation is not valid due to the current state of the object. Source=Calculator.Logic StackTrace: at ~.Calculator.Logic.MyBaseExpressionParser.Parse(String expression) in ~\Source\Calculator.Logic\MyBaseExpressionParser.cs:line 44 at ~.Calculator.Logic.Tests.MyBaseCalculatorServiceTests.BasicMathDivision() in ~\Projects\Tests\Calculator.Logic.Tests\MyBaseCalculatorServiceTests.cs:line 60 InnerException: CalculationNode's code: public sealed calss CalculationNode { public CalculationNode() { this.Left = null; this.Right = null; this.Element = new CalculationElement(); } public CalculationNode Left {get;set;} public CalculationNode Right {get;set;} public CalculationElement Element {get; set;} } CalculationElement's code: public sealed class CalculationElement { public CalculationElement() { Value = string.Empty; IsOperator = false; } public string Value {get; set} public bool IsOperator {get; set} }

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  • Runge-Kutta (RK4) integration for game physics

    - by Kai
    Gaffer on Games has a great article about using RK4 integration for better game physics. The implementation is straightforward but the math behind it confuses me. I understand derivatives and integrals on a conceptual level but I haven't manipulated equations in a long time. Here's the brunt of Gaffer's implementation: void integrate(State &state, float t, float dt) { Derivative a = evaluate(state, t, 0.0f, Derivative()); Derivative b = evaluate(state, t+dt*0.5f, dt*0.5f, a); Derivative c = evaluate(state, t+dt*0.5f, dt*0.5f, b); Derivative d = evaluate(state, t+dt, dt, c); const float dxdt = 1.0f/6.0f * (a.dx + 2.0f*(b.dx + c.dx) + d.dx); const float dvdt = 1.0f/6.0f * (a.dv + 2.0f*(b.dv + c.dv) + d.dv) state.x = state.x + dxdt * dt; state.v = state.v + dvdt * dt; } Can anybody explain in simple terms how RK4 works? Specifically, why are we averaging the derivatives at 0.0f, 0.5f, 0.5f, and 1.0f? How is averaging derivatives up to the 4th order different from doing a simple euler integration with a smaller timestep? After reading the accepted answer below, and several other articles, I have a grasp on how RK4 works. To answer my own questions: Can anybody explain in simple terms how RK4 works? RK4 takes advantage of the fact that we can get a much better approximation of a function if we use its higher-order derivatives rather than just the first or second derivative. That's why the Taylor series converges much faster than Euler approximations. (take a look at the animation on the right side of that page) Specifically, why are we averaging the derivatives at 0.0f, 0.5f, 0.5f, and 1.0f? The Runge-Kutta method is an approximation of a function that samples derivatives of several points within a timestep, unlike the Taylor series which only samples derivatives of a single point. After sampling these derivatives we need to know how to weigh each sample to get the closest approximation possible. An easy way to do this is to pick constants that coincide with the Taylor series, which is how the constants of a Runge-Kutta equation are determined. This article made it clearer for me: http://web.mit.edu/10.001/Web/Course%5FNotes/Differential%5FEquations%5FNotes/node5.html. Notice how (15) is the Taylor series expansion while (17) is the Runge-Kutta derivation. How is averaging derivatives up to the 4th order different from doing a simple euler integration with a smaller timestep? Mathematically it converges much faster than doing many Euler approximations. Of course, with enough Euler approximations we can gain equal accuracy to RK4, but the computational power needed doesn't justify using Euler.

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  • ViewStateMode in ASP.Net 4.0

    - by sreejukg
    When asp.net introduced the concept of viewstate, it changed the way how developers maintain the state for the controls in a web page. Until then to keep the track of the control(in classic asp), it was the developer responsibility to manually assign the posted content before rendering the control again. Viewstate made allowed the developer to do it with ease. The developers are not bothered about how controls keep there state on post back. Viewstate is rendered to the browser as a hidden variable __viewstate. Since viewstate stores the values of all controls, as the number of controls in the page increases, the content of viewstate grows large. It causes some websites to load slowly. As developers we need viewstate, but actually we do not want this for all the controls in the page. Till asp.net 3.5, if viewstate is disabled from web.config (using <pages viewstate=”false”/> ..</pages>), then you can not enable it from the control level/page level. Both <%@ Page EnableViewState=”true”…. and <asp:textbox EnableViewState=”true” will not work in this case. Lot of developers demands for more control over viewstate. It will be useful if the developers are able to disable it for the entire page and enable it for only those controls that needed viewstate. With ASP.NET 4.0, this is possible, a happy news for the developers. This is achieved by introducing a new property called ViewStateMode. Let us see, What is ViewStateMode – Is a new property in asp.net 4.0, that allows developers to enable viewstate for individual control even if the parent has disabled it. This ViewStateMode property can contain either of three values Enabled- Enable view state for the control even if the parent control has view state disabled. Disabled - Disable view state for this control even if the parent control has view state enabled Inherit - Inherit the value of ViewStateMode from the parent, this is the default value. To disable view state for a page and to enable it for a specific control on the page, you can set the EnableViewState property of the page to true, then set the ViewStateMode property of the page to Disabled, and then set the ViewStateMode property of the control to Enabled. Find the example below. Page directive - <%@ Page Language="C#"  EnableViewState="True" ViewStateMode="Disabled" .......... %> Code for the control  - <asp:TextBox runat="server" ViewStateMode="Enabled" ............../> Now the viewstate will be disabled for the whole page, but enabled for the TextBox. ViewStateMode gives developers more control over the viewstate.

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  • .htaccess to block by file name possible?

    - by Tiffany Walker
    I have a bunch of files that are secure_xxxxxx.php. Is there a way to use .htaccess to block access to all the secure_* php files based on IP? EDIT: I've tried but I get 500 errors <FilesMatch "^secure_.*\.php$"> order deny all deny from all allow from my ip here </FilesMatch> Don't see any errors in apache error logs either httpd -M Loaded Modules: core_module (static) authn_file_module (static) authn_default_module (static) authz_host_module (static) authz_groupfile_module (static) authz_user_module (static) authz_default_module (static) auth_basic_module (static) include_module (static) filter_module (static) log_config_module (static) logio_module (static) env_module (static) expires_module (static) headers_module (static) setenvif_module (static) version_module (static) proxy_module (static) proxy_connect_module (static) proxy_ftp_module (static) proxy_http_module (static) proxy_scgi_module (static) proxy_ajp_module (static) proxy_balancer_module (static) ssl_module (static) mpm_prefork_module (static) http_module (static) mime_module (static) dav_module (static) status_module (static) autoindex_module (static) asis_module (static) info_module (static) suexec_module (static) cgi_module (static) dav_fs_module (static) negotiation_module (static) dir_module (static) actions_module (static) userdir_module (static) alias_module (static) rewrite_module (static) so_module (static) fastinclude_module (shared) auth_passthrough_module (shared) bwlimited_module (shared) frontpage_module (shared) suphp_module (shared) Syntax OK

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  • Auto-mount in fstab no longer working until manually running 'sudo mount -a'

    - by Brett Alton
    I have 3 SMB shared drives I need to connect to for work purposes. I had Ubuntu 10.10 Maverick and had all my drives loaded into fstab to be auto-mounted. Everything worked fine for a while but just before I upgraded to 11.04 Natty, the fstab auto-mount stopped working. Unfortunately I don't know what changed I made to my machine or what update installed that made this occur. /etc/fstab {snip} //192.168.7.3/apache_proj/ /home/brett/Desktop/apache smbfs guest,rw,iocharset=utf8,uid=1000,gid=1000 0 0 //192.168.7.3/apache_54321/ /home/brett/Desktop/54321 smbfs guest,rw,iocharset=utf8,uid=1000,gid=1000 0 0 //freenas.local/shared/ /home/brett/Desktop/shared smbfs guest,rw,iocharset=utf8,uid=1000,gid=1000 0 0 //lamp/www/ /home/brett/Desktop/lamp smbfs username={snip},password={snip},rw,iocharset=utf8,uid=1000,gid=1000 0 0 When the machine boots, I run this command to get them to mount: $ sudo umount /home/brett/Desktop/54321 /home/brett/Desktop/shared /home/brett/Desktop/apache; sudo mount -a [sudo] password for brett: umount: /home/brett/Desktop/54321: not mounted umount: /home/brett/Desktop/shared: not mounted umount: /home/brett/Desktop/apache: not mounted Warning: mapping 'guest' to 'guest,sec=none' Warning: mapping 'guest' to 'guest,sec=none' Warning: mapping 'guest' to 'guest,sec=none' mount error: could not resolve address for lamp: No address associated with hostname (I run that umount as a just-in-case). I looked through dmesg and some error logs and couldn't see why fstab was failing on my mounts. I see that my 'lamp' directive is failing, but that's because the machine is currently down.

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  • Live Debugging

    - by Daniel Moth
    Based on my classification of diagnostics, you should know what live debugging is NOT about - at least according to me :-) and in this post I'll share how I think of live debugging. These are the (outer) steps to live debugging Get the debugger in the picture. Control program execution. Inspect state. Iterate between 2 and 3 as necessary. Stop debugging (and potentially start new iteration going back to step 1). Step 1 has two options: start with the debugger attached, or execute your binary separately and attach the debugger later. You might say there is a 3rd option, where the app notifies you that there is an issue, referred to as JIT debugging. However, that is just a variation of the attach because that is when you start the debugging session: when you attach. I'll be covering in future posts how this step works in Visual Studio. Step 2 is about pausing (or breaking) your app so that it makes no progress and remains "frozen". A sub-variation is to pause only parts of its execution, or in other words to freeze individual threads. I'll be covering in future posts the various ways you can perform this step in Visual Studio. Step 3, is about seeing what the state of your program is when you have paused it. Typically it involves comparing the state you are finding, with a mental picture of what you thought the state would be. Or simply checking invariants about the intended state of the app, with the actual state of the app. I'll be covering in future posts the various ways you can perform this step in Visual Studio. Step 4 is necessary if you need to inspect more state - rinse and repeat. Self-explanatory, and will be covered as part of steps 2 & 3. Step 5 is the most straightforward, with 3 options: Detach the debugger; terminate your binary though the normal way that it terminates (e.g. close the main window); and, terminate the debugging session through your debugger with a result that it terminates the execution of your program too. In a future post I'll cover the ways you can detach or terminate the debugger in Visual Studio. I found an old picture I used to use to map the steps above on Visual Studio 2010. It is basically the Debug menu with colored rectangles around each menu mapping the menu to one of the first 3 steps (step 5 was merged with step 1 for that slide). Here it is in case it helps: Stay tuned for more... Comments about this post by Daniel Moth welcome at the original blog.

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  • How do I clean build and installs, ie un-build?

    - by Kaustubh P
    I have installed and downloaded and built mongodb, and just one works. $ mongo mongo: error while loading shared libraries: libmozjs.so: cannot open shared object file: No such file or directory $ /opt/mongo/bin/mongo /opt/mongo/bin/mongo: error while loading shared libraries: libboost_system-mt.so.1.38.0: cannot open shared object file: No such file or directory $ /usr/bin/mongo MongoDB shell version: 1.6.5 connecting to: test > I can remove the installation via apt-get. But how do I remove all things mongo that were built with make, and get a clean system? I followed this guide to build and install mongodb. Thanks.

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  • Rails and Mongoid best way to implement sharing system

    - by Matteo Pagliazzi
    I have to model User and Board in rails using mongoid as ODM. Each board is referenced to an user through a foreign key user_id and now I want to add the ability to share a board with other users. Following CRUD I'd create a new Model called something like Share and it's releated Controller with the ability to create/edit/delete a Share but I have some doubts: First, where to save informations about Shares? I think I may create a field in the Board's collection called shared_with including an array of user ids. in a MySQL I'd created a new table with the ids of who share, the resource shared and the user the resources is shared with but I don't think that's necessary using MongoDB. Every user a Board is shared with should be able to edit the Board (but not to delete it) so the Board should have two relations one with the owner and another with the users the board is shared with, right? For permission (the owner should be able to delete a board but the users it is shared with shouldn't) what to use? I'm using Devise for authentication but I think something like CanCan would fit better. but how to implement it? What do you think about this way? Do you find any problems or have better solutions?

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  • How to salvage SQL server 2008 query from KILLED/ROLLBACK state?

    - by littlegreen
    I have a stored procedure that inserts batches of millions of rows, emerging from a certain query, into an SQL database. It has one parameter selecting the batch; when this parameter is omitted, it will gather a list of batches and recursively call itself, in order to iterate over batches. In (pseudo-)code, it looks something like this: CREATE PROCEDURE spProcedure AS BEGIN IF @code = 0 BEGIN ... WHILE @@Fetch_Status=0 BEGIN EXEC spProcedure @code FETCH NEXT ... INTO @code END END ELSE BEGIN -- Disable indexes ... INSERT INTO table SELECT (...) -- Enable indexes ... Now it can happen that this procedure is slow, for whatever reason: it can't get a lock, one of the indexes it uses is misdefined or disabled. In that case, I want to be able kill the procedure, truncate and recreate the resulting table, and try again. However, when I try and kill the procedure, the process frequently oozes into a KILLED/ROLLBACK state from which there seems to be no return. From Google I have learned to do an sp_lock, find the spid, and then kill it with KILL <spid>. But when I try to kill it, it tells me SPID 75: transaction rollback in progress. Estimated rollback completion: 0%. Estimated time remaining: 554 seconds. I did find a forum message hinting that another spid should be killed before the other one can start a rollback. But that didn't work for me either, plus I do not understand, why that would be the case... could it be because I am recursively calling my own stored procedure? (But it should be having the same spid, right?) In any case, my process is just sitting there, being dead, not responding to kills, and locking the table. This is very frustrating, as I want to go on developing my queries, not waiting hours on my server sitting dead while pretending to be finishing a supposed rollback. Is there some way in which I can tell the server not to store any rollback information for my query? Or not to allow any other queries to interfere with the rollback, so that it will not take so long? Or how to rewrite my query in a better way, or how kill the process successfully without restarting the server?

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  • Using Windows Previous Versions to access ZFS Snapshots (July 14, 2009)

    - by user12612012
    The Previous Versions tab on the Windows desktop provides a straightforward, intuitive way for users to view or recover files from ZFS snapshots.  ZFS snapshots are read-only, point-in-time instances of a ZFS dataset, based on the same copy-on-write transactional model used throughout ZFS.  ZFS snapshots can be used to recover deleted files or previous versions of files and they are space efficient because unchanged data is shared between the file system and its snapshots.  Snapshots are available locally via the .zfs/snapshot directory and remotely via Previous Versions on the Windows desktop. Shadow Copies for Shared Folders was introduced with Windows Server 2003 but subsequently renamed to Previous Versions with the release of Windows Vista and Windows Server 2008.  Windows shadow copies, or snapshots, are based on the Volume Snapshot Service (VSS) and, as the [Shared Folders part of the] name implies, are accessible to clients via SMB shares, which is good news when using the Solaris CIFS Service.  And the nice thing is that no additional configuration is required - it "just works". On Windows clients, snapshots are accessible via the Previous Versions tab in Windows Explorer using the Shadow Copy client, which is available by default on Windows XP SP2 and later.  For Windows 2000 and pre-SP2 Windows XP, the client software is available for download from Microsoft: Shadow Copies for Shared Folders Client. Assuming that we already have a shared ZFS dataset, we can create ZFS snapshots and view them from a Windows client. zfs snapshot tank/home/administrator@snap101zfs snapshot tank/home/administrator@snap102 To view the snapshots on Windows, map the dataset on the client then right click on a folder or file and select Previous Versions.  Note that Windows will only display previous versions of objects that differ from the originals.  So you may have to modify files after creating a snapshot in order to see previous versions of those files. The screenshot above shows various snapshots in the Previous Versions window, created at different times.  On the left panel, the .zfs folder is visible, illustrating that this is a ZFS share.  The .zfs setting can be toggled as desired, it makes no difference when using previous versions.  To make the .zfs folder visible: zfs set snapdir=visible tank/home/administrator To hide the .zfs folder: zfs set snapdir=hidden tank/home/administrator The following screenshot shows the Previous Versions panel when a file has been selected.  In this case the user is prompted to view, copy or restore the file from one of the available snapshots. As can be seen from the screenshots above, the Previous Versions window doesn't display snapshot names: snapshots are listed by snapshot creation time, sorted in time order from most recent to oldest.  There's nothing we can do about this, it's the way that the interface works.  Perhaps one point of note, to avoid confusion, is that the ZFS snapshot creation time isnot the same as the root directory creation timestamp. In ZFS, all object attributes in the original dataset are preserved when a snapshot is taken, including the creation time of the root directory.  Thus the root directory creation timestamp is the time that the directory was created in the original dataset. # ls -d% all /home/administrator         timestamp: atime         Mar 19 15:40:23 2009         timestamp: ctime         Mar 19 15:40:58 2009         timestamp: mtime         Mar 19 15:40:58 2009         timestamp: crtime         Mar 19 15:18:34 2009 # ls -d% all /home/administrator/.zfs/snapshot/snap101         timestamp: atime         Mar 19 15:40:23 2009         timestamp: ctime         Mar 19 15:40:58 2009         timestamp: mtime         Mar 19 15:40:58 2009         timestamp: crtime         Mar 19 15:18:34 2009 The snapshot creation time can be obtained using the zfs command as shown below. # zfs get all tank/home/administrator@snap101NAME                             PROPERTY  VALUEtank/home/administrator@snap101  type      snapshottank/home/administrator@snap101  creation  Mon Mar 23 18:21 2009 In this example, the dataset was created on March 19th and the snapshot was created on March 23rd. In conclusion, Shadow Copies for Shared Folders provides a straightforward way for users to view or recover files from ZFS snapshots.  The Windows desktop provides an easy to use, intuitive GUI and no configuration is required to use or access previous versions of files or folders. REFERENCES FOR MORE INFORMATION ZFS ZFS Learning Center Introduction to Shadow Copies of Shared Folders Shadow Copies for Shared Folders Client

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  • Lua and Objective C not running script.

    - by beta
    I am trying to create an objective c interface that encapsulates the functionality of storing and running a lua script (compiled or not.) My code for the script interface is as follows: #import <Cocoa/Cocoa.h> #import "Types.h" #import "lua.h" #include "lualib.h" #include "lauxlib.h" @interface Script : NSObject<NSCoding> { @public s32 size; s8* data; BOOL done; } @property s32 size; @property s8* data; @property BOOL done; - (id) initWithScript: (u8*)data andSize:(s32)size; - (id) initFromFile: (const char*)file; - (void) runWithState: (lua_State*)state; - (void) encodeWithCoder: (NSCoder*)coder; - (id) initWithCoder: (NSCoder*)coder; @end #import "Script.h" @implementation Script @synthesize size; @synthesize data; @synthesize done; - (id) initWithScript: (s8*)d andSize:(s32)s { self = [super init]; self->size = s; self->data = d; return self; } - (id) initFromFile:(const char *)file { FILE* p; p = fopen(file, "rb"); if(p == NULL) return [super init]; fseek(p, 0, SEEK_END); s32 fs = ftell(p); rewind(p); u8* buffer = (u8*)malloc(fs); fread(buffer, 1, fs, p); fclose(p); return [self initWithScript:buffer andSize:size]; } - (void) runWithState: (lua_State*)state { if(luaL_loadbuffer(state, [self data], [self size], "Script") != 0) { NSLog(@"Error loading lua chunk."); return; } lua_pcall(state, 0, LUA_MULTRET, 0); } - (void) encodeWithCoder: (NSCoder*)coder { [coder encodeInt: size forKey: @"Script.size"]; [coder encodeBytes:data length:size forKey:@"Script.data"]; } - (id) initWithCoder: (NSCoder*)coder { self = [super init]; NSUInteger actualSize; size = [coder decodeIntForKey: @"Script.size"]; data = [[coder decodeBytesForKey:@"Script.data" returnedLength:&actualSize] retain]; return self; } @end Here is the main method: #import "Script.h" int main(int argc, char* argv[]) { Script* script = [[Script alloc] initFromFile:"./test.lua"]; lua_State* state = luaL_newstate(); luaL_openlibs(state); luaL_dostring(state, "print(_VERSION)"); [script runWithState:state]; luaL_dostring(state, "print(_VERSION)"); lua_close(state); } And the lua script is just: print("O Hai World!") Loading the file is correct, but I think it messes up at pcall. Any Help is greatly appreciated. Heading

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  • Chargeback and showback...both a 'throw back'

    - by llaszews
    Been getting asked again by customers and partners about chargeback and showback in the cloud so thought I would blog on my response to this question. Charge Back background, information and industry analysis: Cloud computing is all about shared resources. These shared resources are computer servers (including memory and CPU), network devices, hard disk storage, database servers, application servers, cooling, floor space, electricity and more. These resources are shared by departments within a company, or by a number of companies, when resources are hosted in the public or hybrid cloud. Currently, hosting providers that run other companies on their cloud platforms do not have an accurate way to measure the shared computing resources used by a specific user let alone used by a specific customer. Additionally, companies running their own cloud data centers, for private or hybrid clouds, have no way of measure and charging back the departments in the company that are using these shared cloud resources. In both cases, the lack of determine shared resource costs and to charge them back to the company, department or user that is using this resources is limited a clear measure of business benefit and impacting company’s ability to measure the Return on Investment (ROI). An IT chargeback system is an accounting strategy that applies the costs of IT services, hardware or software to the business unit in which they are used. This system contrasts with traditional IT accounting models in which a centralized department bears all of the IT costs in an organization and those costs are treated simply as corporate overhead. Showback involves showing the IT costs to a department or customer but not actually charging them for their IT usage. Showback is a gradual method of introducing chargeback into an enterprise. Most companies implement a show back mechanism before a full chargeback system is put in place. Oracle chargeback product: Oracle Enterprise Manager provides tools for defining detailed Chargeback plans spanning different metrics collected for each type of resources as well as defining Cost Centers for grouping costs across multiple developers. Chargeback plans can use not only usage based costs, but also configuration based costs (e.g. version of the platform) or fixed costs (e.g. flat-rate management fee). Chargeback has rich out of the box reports. Trending reports show how charge and resource consumption varies over time, while Summary reports show the breakdown of charges or usage by different dimensions such as Cost Center or Target Type. These reports help consumers in understanding how their charges relate to their consumption and also assist the IT department with budgeting and planning activities. With BI Publisher, the reports can be made available in a variety of formats such as PDF, HTML, Word, Excel or PowerPoint.

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  • Samba issue with sharing directories on NTFS/FAT32

    - by Microkernel
    I have some strange problems with Samba server. I am using samba Version 3.5.4 on Ubuntu 10.10. I have two Windows XP machines, one on VirtualBox on Ubuntu and another office laptop. Windows machine on VirtualBox has no issues in accessing the shared folders, but the laptop is not able to access all the shared content. The issue faced on laptop is the following. Shared folders on ext3 drives have no issues in accessing, but the contents shared on NTFS and FAT32 drives (mounted ones) are not accessible. When I try to open the shared folder, it asks for user name and password, but doesn't accept when I provide it. (Even if I provide admin login details). I changed workgroup value to the domain_name in office laptop, but still the problem persists. Here is the smdb.conf I am using: [global] workgroup = XXX.XXX.ORG server string = %h server (Samba, Ubuntu) map to guest = Bad User obey pam restrictions = Yes pam password change = Yes passwd program = /usr/bin/passwd %u passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* . unix password sync = Yes syslog = 0 log file = /var/log/samba/log.%m max log size = 1000 dns proxy = No usershare allow guests = Yes panic action = /usr/share/samba/panic-action %d guest ok = Yes [homes] comment = Home Directories [printers] comment = All Printers path = /var/spool/samba read only = No create mask = 0700 printable = Yes browseable = No [print$] comment = Samba server's CD-ROM path = /cdrom force user = nobody force group = nobody locking = No Workgroup was defined as "HOMENET" before, changed it to domain name on the office laptop thinking it was the problem, but for no avail.

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  • C-states and P-states : confounding factors for benchmarking

    - by Dave
    I was recently looking into a performance issue in the java.util.concurrent (JUC) fork-join pool framework related to particularly long latencies when trying to wake (unpark) threads in the pool. Eventually I tracked the issue down to the power & scaling governor and idle-state policies on x86. Briefly, P-states refer to the set of clock rates (speeds) at which a processor can run. C-states reflect the possible idle states. The deeper the C-state (higher numerical values) the less power the processor will draw, but the longer it takes the processor to respond and exit that sleep state on the next idle to non-idle transition. In some cases the latency can be worse than 100 microseconds. C0 is normal execution state, and P0 is "full speed" with higher Pn values reflecting reduced clock rates. C-states are P-states are orthogonal, although P-states only have meaning at C0. You could also think of the states as occupying a spectrum as follows : P0, P1, P2, Pn, C1, C2, ... Cn, where all the P-states are at C0. Our fork-join framework was calling unpark() to wake a thread from the pool, and that thread was being dispatched onto a processor at deep C-state, so we were observing rather impressive latencies between the time of the unpark and the time the thread actually resumed and was able to accept work. (I originally thought we were seeing situations where the wakee was preempting the waker, but that wasn't the case. I'll save that topic for a future blog entry). It's also worth pointing out that higher P-state values draw less power and there's usually some latency in ramping up the clock (P-states) in response to offered load. The issue of C-states and P-states isn't new and has been described at length elsewhere, but it may be new to Java programmers, adding a new confounding factor to benchmarking methodologies and procedures. To get stable results I'd recommend running at C0 and P0, particularly for server-side applications. As appropriate, disabling "turbo" mode may also be prudent. But it also makes sense to run with the system defaults to understand if your application exhibits any performance sensitivity to power management policies. The operating system power management sub-system typically control the P-state and C-states based on current and recent load. The scaling governor manages P-states. Operating systems often use adaptive policies that try to avoid deep C-states for some period if recent deep idle episodes proved to be very short and futile. This helps make the system more responsive under bursty or otherwise irregular load. But it also means the system is stateful and exhibits a memory effect, which can further complicate benchmarking. Forcing C0 + P0 should avoid this issue.

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  • ACL and moving files in Nautilus

    - by MyOnlyEye
    When I move files from a private home directory (e.g. /home/jack) to a shared directory (e.g. /home/shared-school) Nautilus copies the file permissions from the original file into the shared directory - and ignores the ACL that I've put in the /home/shared-school directory (e.g. setfacl -R -m d:g:school:rwx /home/shared-school). Is it possible to force Nautilus to change ACL on a file that is moved or copied - or not to ignore the ACL on the directory where the files are moved or copied?

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  • Share Mulitple Classes as one dll or a lib with Mulitple Projects

    - by JNL
    Currently I have some shared class files(.cpp and .h) which I include them in around 20 Projects. Currently I have to include them in all of the projects. So if I get some business requirments and I change some of the shared(.cpp or .h) files I have to include them in all the 20 Projects which is kind of tedious. Is there a way where I can create a shared dll or library and include it all of my Projects. So if I have to change it, I just have to change it once and then just Add Reference to include that dll or library which contains all the shared(.cpp, .h) files. Any help/recommendations regarding the same, will be highly appreciated. I am using VS2012 for VC++.

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  • Optimal Database design regarding functionality of letting user share posts by other users

    - by codecool
    I want to implement functionality which let user share posts by other users similar to what Facebook and Google+ share button and twitter retweet. There are 2 choices: 1) I create duplicate copy of the post and have a column which keeps track of the original post id and makes clear this is a shared post. 2) I have a separate table shared post where I save the post id which is a foreign key to post id in post table. Talking in terms of programming basically I keep pointer to the original post in a separate table and when need to get post posted by user and also shared ones I do a left join on post and shared post table Post(post_id(PK), post_content, posted_by) SharedPost(post_id(FK to Post.post_id), sharing_user, sharedfrom(in case someone shares from non owners profile)) I am in favour of second choice but wanted to know the advice of experts out there? One thing more posts on my webapp will be more on the lines of facebook size not tweet size.

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  • can't the asp file system object access shared server paths?

    - by sushant
    i am using this code to access files and folders. <%@ Language=VBScript %><% option explicit dim sRoot, sDir, sParent, objFSO, objFolder, objFile, objSubFolder, sSize %> <META content="Microsoft Visual Studio 6.0" name=GENERATOR><!-- Author: Adrian Forbes --> <% sRoot = "D:Raghu" sDir = Request("Dir") sDir = sDir & "\" Response.Write "<h1>" & sDir & "</h1>" & vbCRLF Set objFSO = CreateObject("Scripting.FileSystemObject") on error resume next Set objFolder = objFSO.GetFolder(sRoot & sDir) if err.number <> 0 then Response.Write "Could not open folder" Response.End end if on error goto 0 sParent = objFSO.GetParentFolderName(objFolder.Path) ' Remove the contents of sRoot from the front. This gives us the parent ' path relative to the root folder ' eg. if parent folder is "c:webfilessubfolder1subfolder2" then we just want "subfolder1subfolder2" sParent = mid(sParent, len(sRoot) + 1) Response.Write "<table border=""1"">" ' Give a link to the parent folder. This is just a link to this page only pssing in ' the new folder as a parameter Response.Write "<tr><td colspan=3><a href=""browse.asp?dir=" & Server.URLEncode(sParent) & """>Parent folder</a></td></tr>" & vbCRLF ' Now we want to loop through the subfolders in this folder For Each objSubFolder In objFolder.SubFolders ' And provide a link to them Response.Write "<tr><td colspan=3><a href=""browse.asp?dir=" & Server.URLEncode(sDir & objSubFolder.Name) & """>" & objSubFolder.Name & "</a></td></tr>" & vbCRLF Next ' Now we want to loop through the files in this folder For Each objFile In objFolder.Files if Clng(objFile.Size) < 1024 then sSize = objFile.Size & " bytes" else sSize = Clng(objFile.Size / 1024) & " KB" end if ' And provide a link to view them. This is a link to show.asp passing in the directory and the file ' as parameters Response.Write "<tr><td><a href=""show.asp?file=" & server.URLEncode(objFile.Name) & "&dir=" & server.URLEncode (sDir) & """>" & objFile.Name & "</a></td><td>" & sSize & "</td><td>" & objFile.Type & "</td></tr>" & vbCRLF Next Response.Write "</table>" %> it works fine. but when i try to access something on shared path like: "\\cvrdd0110:share" it gives error. how to access these files? and sorry for formatting issues.

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  • Xpath expression to retrieve oldest/earliest node

    - by gkrogers
    I have an XML snippet, so: <STATES> <STATE> <NAME>Alabama</NAME> <ABBREVIATION>AL</ABBREVIATION> <CAPITAL>Montgomery</CAPITAL> <POPULATION>4661900</POPULATION> <AREA>52419</AREA> <DATEOFSTATEHOOD>14 December 1819</DATEOFSTATEHOOD> </STATE> <STATE> <NAME>Alaska</NAME> <ABBREVIATION>AK</ABBREVIATION> <CAPITAL>Juneau</CAPITAL> <POPULATION>698473</POPULATION> <AREA>663268</AREA> <DATEOFSTATEHOOD>1 January 1959</DATEOFSTATEHOOD> </STATE> <STATE> <NAME>Delaware</NAME> <ABBREVIATION>DE</ABBREVIATION> <CAPITAL>Dover</CAPITAL> <POPULATION>885122</POPULATION> <AREA>2490</AREA> <DATEOFSTATEHOOD>7 December 1787</DATEOFSTATEHOOD> </STATE> </STATES> <etc, etc.> I want to retrieve (for example) the capital of the oldest state (i.e. "Dover"). I have managed to get this far: //STATES/STATE[DATEOFSTATEHOOD='7 December 1787']/CAPITAL/text() but can't figure out how to say 'DATEOFSTATEHOOD={the earliest DATEOFSTATEHOOD}'. Can anybody point me in the right direction, please? SOLUTION: Matt's solution is more or less spot on. I had to reformat the dates (I used YYYYMMDDD) because, as was pointed out, Xpath 1.0 doesn't support the date format I was using. Also, Microsoft's XML library (4.0 and 6.0) returned the whole node list with Matt's expression. Reversing the test fixed that problem, making it return just the earliest node. So: //STATES/STATE[(DATEOFSTATEHOOD < //STATES/STATE/DATEOFSTATEHOOD)]/CAPITAL/text()

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  • Consolidation in a Database Cloud

    - by B R Clouse
    Consolidation of multiple databases onto a shared infrastructure is the next step after Standardization.  The potential consolidation density is a function of the extent to which the infrastructure is shared.  The three models provide increasing degrees of sharing: Server: each database is deployed in a dedicated VM. Hardware is shared, but most of the software infrastructure is not. Standardization is often applied incompletely since operating environments can be moved as-is onto the shared platform. The potential for VM sprawl is an additional downside. Database: multiple database instances are deployed on a shared software / hardware infrastructure. This model is very efficient and easily implemented with the features in the Oracle Database and supporting products. Many customers have moved to this model and achieved significant, measurable benefits. Schema: multiple schemas are deployed within a single database instance. The most efficient model, it places constraints on the environment. Usually this model will be implemented only by customers deploying their own applications.  (Note that a single deployment can combine Database and Schema consolidations.) Customer value: lower costs, better system utilization In this phase of the maturity model, under-utilized hardware can be used to host more workloads, or retired and those workloads migrated to consolidation platforms. Customers benefit from higher utilization of the hardware resources, resulting in reduced data center floor space, and lower power and cooling costs. And, the OpEx savings from Standardization are multiplied, since there are fewer physical components (both hardware and software) to manage. Customer value: higher productivity The OpEx benefits from Standardization are compounded since not only are there fewer types of things to manage, now there are fewer entities to manage. In this phase, customers discover that their IT staff has time to move away from "day-to-day" tasks and start investing in higher value activities. Database users benefit from consolidating onto shared infrastructures by relieving themselves of the requirement to maintain their own dedicated servers. Also, if the shared infrastructure offers capabilities such as High Availability / Disaster Recovery, which are often beyond the budget and skillset of a standalone database environment, then moving to the consolidation platform can provide access to those capabilities, resulting in less downtime. Capabilities / Characteristics In this phase, customers will typically deploy fixed-size clusters and consolidate on a cluster until that cluster is deemed "full," at which point a new cluster is built. Customers will define one or a few cluster architectures that are used wherever possible; occasionally there may be deployments which must be handled as exceptions. The "full" policy may be based on number of databases deployed on the cluster, or observed peak workload, etc. IT will own the provisioning of new databases on a cluster, making the decision of when and where to place new workloads. Resources may be managed dynamically, e.g., as a priority workload increases, it may be given more CPU and memory to handle the spike. Users will be charged at a fixed, relatively coarse level; or in some cases, no charging will be applied. Activities / Tasks Oracle offers several tools to plan a successful consolidation. Real Application Testing (RAT) has a feature to help plan and validate database consolidations. Enterprise Manager 12c's Cloud Management Pack for Database includes a planning module. Looking ahead, customers should start planning for the Services phase by defining the Service Catalog that will be made available for database services.

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  • How to salvage SQL server 2008 query from KILLED/ROLLBACK state without waiting half a day?

    - by littlegreen
    I have a stored procedure that inserts batches of millions of rows, emerging from a certain query, into an SQL database. It has one parameter selecting the batch; when this parameter is omitted, it will gather a list of batches and recursively call itself, in order to iterate over batches. In (pseudo-)code, it looks something like this: CREATE PROCEDURE spProcedure AS BEGIN IF @code = 0 BEGIN ... WHILE @@Fetch_Status=0 BEGIN EXEC spProcedure @code FETCH NEXT ... INTO @code END END ELSE BEGIN -- Disable indexes ... INSERT INTO table SELECT (...) -- Enable indexes ... Now it can happen that this procedure is slow, for whatever reason: it can't get a lock, one of the indexes it uses is misdefined or disabled. In that case, I want to be able kill the procedure, truncate and recreate the resulting table, and try again. However, when I try and kill the procedure, the process frequently oozes into a KILLED/ROLLBACK state from which there seems to be no return. From Google I have learned to do an sp_lock, find the spid, and then kill it with KILL <spid>. But when I try to kill it, it tells me SPID 75: transaction rollback in progress. Estimated rollback completion: 0%. Estimated time remaining: 554 seconds. I did find a forum message hinting that another spid should be killed before the other one can start a rollback. But that didn't work for me either, plus I do not understand, why that would be the case... could it be because I am recursively calling my own stored procedure? (But it should be having the same spid, right?) In any case, my process is just sitting there, being dead, not responding to kills, and locking the table. This is very frustrating, as I want to go on developing my queries, not waiting hours on my server sitting dead while pretending to be finishing a supposed rollback. Is there some way in which I can tell the server not to store any rollback information for my query? Or not to allow any other queries to interfere with the rollback, so that it will not take so long? Or how to rewrite my query in a better way, or how kill the process successfully without restarting the server?

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  • Samba issue with sharing directories on NTFS/FAT32 (Mounted Drives) ???

    - by Microkernel
    Hi guys, I have some strange problems with Samba server. I am using samba Version 3.5.4 on Ubuntu 10.10. I have two windows-xp machines, one on VirtualBox on Ubuntu and another office laptop. Windows machine on VBox has no issues in accessing the shared folders, but the laptop is not able to access all the shared content. The issue faced on laptop is = Shared folders on Ext3 drives have no issues in accessing, but the contents shared on NTFS and FAT32 drives (mounted ones) are not accessible. When I try to open the shared folder, it asks for user name and password, but doesn't accept when I provide it. (even if I provide admin login details!!!). I changed workgroup value to the domain_name in office laptop, but still the problem persists... Here is the smdb.conf I am using... [global] workgroup = XXX.XXX.ORG server string = %h server (Samba, Ubuntu) map to guest = Bad User obey pam restrictions = Yes pam password change = Yes passwd program = /usr/bin/passwd %u passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* . unix password sync = Yes syslog = 0 log file = /var/log/samba/log.%m max log size = 1000 dns proxy = No usershare allow guests = Yes panic action = /usr/share/samba/panic-action %d guest ok = Yes [homes] comment = Home Directories [printers] comment = All Printers path = /var/spool/samba read only = No create mask = 0700 printable = Yes browseable = No [print$] comment = Samba server's CD-ROM path = /cdrom force user = nobody force group = nobody locking = No Workgroup Was defined as "HOMENET" before, changed it to domain name on the office laptop thinking it was the problem, but for no avail Thanks in advance Regards, Microkernel

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  • How can I make a case for "dependency management"?

    - by C. Ross
    I'm currently trying to make a case for adopting dependency management for builds (ala Maven, Ivy, NuGet) and creating an internal repository for shared modules, of which we have over a dozen enterprise wide. What are the primary selling points of this build technique? The ones I have so far: Eases the process of distributing and importing shared modules, especially version upgrades. Requires the dependencies of shared modules to be precisely documented. Removes shared modules from source control, speeding and simplifying checkouts/check ins (when you have applications with 20+ libraries this is a real factor). Allows more control or awareness of what third party libs are used in your organization. Are there any selling points that I'm missing? Are there any studies or articles giving improvement metrics?

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  • Keep hover state applied until user mouses over another element.

    - by Thomas
    First let me state that I'm a jquery noob, so this may not make a lot of sense. So I have a series of list items that expand to show a hidden div inside if the user mouses over a link inside the item (not the whole list item itself) The problem is that if the users mouse leaves the link the li closes up again. I need this to work in a way so that the li only closes if you mouse over a link in another li. (sorry this is kind of hard to put into words) Heres my code. $(document).ready(function(){ $(".home_upcoming_title").hoverIntent({ over: makeTall, timeout: 500, out: makeShort }); }); // close document.ready function makeTall(){$(this).parents("li").animate({"height":200},200);} function makeShort(){$(this).parents("li").animate({"height":32},200);} and the HTML <li class="p1"> <ul class="home_upcoming_list2" id="fade"> <li class="home_upcoming_date">Sat.Sept.23rd.2010</li> <li><a href="./." class="home_upcoming_title" >Event Title</a></li> <li class="home_upcoming_city">Los Angeles</li> <li class="home_upcoming_type">Festival</li> <li class="home_upcoming_venue">Venue</li> <li class="home_upcoming_age">18+</li> <li><a href="./." title="Buy Tickets" class="home_upcoming_tix">Buy Tickets</a></li> <li><a href="./." class="upcoming_info" title="View Details"></a></li> </ul> <div style="height:150px; background-color:#FF0000; display:block;" class="sl0w"></div> </li> so the link with the class "home_upcoming_title" expands li to show the div inside but when I mouse over the div itself the list closes. I also need it so only the class "home_upcoming_title" expands the div. but it needs to stay open until you mouse over another link with the same class. sorry if that doesn't make much sense :)

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  • How do I install graphviz 2.29 in 12.04?

    - by bidur
    In my ubuntu 12.04, the graphviz is not the latest version(2.29). I need some features available in the latest version of graphviz. I tried to install the graphviz version 2.29, which requires libgraphviz4(=2.18). I anyhow installed libgraphviz4 and installed graphviz 2.29. For that I have to remove packages libcdt4 and libpathplan4. Now whenever I try to generate graph, I get some problems: For e.g.: dot -Kfdp -n -Tpng -o samplePOS.png forcePOS.dot It says: dot: error while loading shared libraries: libgvc.so.6: cannot open shared object file: No such file or directory neato -Tps -o sample_1.ps sourcedot.gv It says: neato: error while loading shared libraries: libgvc.so.6: cannot open shared object file: No such file or directory So, I am looking for some ways so that I can run graphviz 2.29 in my ubuntu 12.04.

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