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  • CentOS vs. Ubuntu

    - by DLH
    I had a web server that ran Ubuntu, but the hard drive failed recently and everything was erased. I decided to try CentOS on the machine instead of Ubuntu, since it's based on Red Hat. That association meant a lot to me because Red Hat is a commercial server product and is officially supported by my server's manufacturer. However, after a few days I'm starting to miss Ubuntu. I have trouble finding some of the packages I want in the CentOS repositories, and the third-party packages I've tried have been a hassle to deal with. My question is, what are the advantages of using CentOS as a server over Ubuntu? CentOS is ostensibly designed for this purpose, but so far I would prefer to use a desktop edition of Ubuntu over CentOS. Are there any killer features of CentOS which make it a better server OS? Is there any reason I shouldn't switch back to Ubuntu Server or Xubuntu?

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  • Pivotal Announces JSR-352 Compliance for Spring Batch

    - by reza_rahman
    Pivotal, the company currently funding development of the popular Spring Framework, recently announced JSR 352 (aka Batch Applications for the Java Platform) compliance for the Spring Batch project. More specifically, Spring Batch targets JSR-352 Java SE runtime compatibility rather than Java EE runtime compatibility. If you are surprised that APIs included in Java EE can pass TCKs targeted for Java SE, you should not be. Many other Java EE APIs target compatibility in Java SE environments such as JMS and JPA. You can read about Spring Batch's support for JSR-352 here as well as the Spring configuration to get JSR-352 working in Spring (typically a very low level implementation concern intended to be completely transparent to most JSR-352 users). JSR 352 is one of the few very encouraging cases of major active contribution to the Java EE standard from the Spring development team (the other major effort being Rod Johnson's co-leadership of JSR 330 along with Bob Lee). While IBM's Christopher Vignola led the spec and contributed IBM's years of highly mission critical batch processing experience from products like WebSphere Compute Grid and z/OS batch, the Spring team provided major influences to the API in particular for the chunk processing, listeners, splits and operational interfaces. The GlassFish team's own Mahesh Kannan also contributed, in particular by implementing much of the Java EE integration work for the reference implementation. This was an excellent example of multilateral engineering collaboration through the standards process. For many complex reasons it is not too hard to find evidence of less than amicable interaction between the Spring ecosystem and the Java EE standard over the years if one cares to dig deep enough. In reality most developers see Spring and Java EE as two sides of the same server-side Java coin. At the core Spring and Java EE ecosystems have always shared deep undercurrents of common user bases, bi-directional flows of ideas and perhaps genuine if not begrudging mutual respect. We can all hope for continued strength for both ecosystems and graceful high notes of collaboration via efforts like JSR 352.

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  • Vista Startup Repair cannot repair my Toshiba Laptop (L300D)

    - by tdot
    I installed some updates, and now the computer doesn't boot up, it just keep's telling me to go to repair, which doesn't fix the problem. I see the BSOD on startup, but it flashes by too quick. (I also don't have Vista on DVD to do a reinstall if I need to) This is what I get from the Startup Repair details Problem Event Name StartupRepair V2 Problem Signature 01: External Media Problem Signature 02: 6.0.6001.18000.6.0.6001.18000 Problem Signature 03: 2 Problem Signature 04: 131074 Problem Signature 05: BadDriver Problem Signature 06: NoBootFailure Problem Signature 07: 0 Problem Signature 08: 0 Problem Signature 09: unknown Problem Signature 10: 1168 OS Version: 6.0.6001.2.1.0.256.1 Local ID: 1033 Any help will be appreciated. Thanks.

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  • Understanding Windows 8 Recovery options

    - by stuffe
    Background: I am preparing a PC that I am sending to a relative abroad, who has little or no internet access, and next to no sensible options for getting IT support should anything go wrong. As such I am trying to provide a full set of recovery options such that they are able to reinstall the OS with minimum fuss or assistance if required. The PC is a brand new Acer laptop that came with Windows 7 pre-installed (and an associated recovery partition) and a free upgrade to Windows 8. I have installed Windows 8 from scratch performing a format and clean install from media I burned from the official download. The existing Windows 7 recovery partition is still there, and I can still boot from it. I have created recovery DVDs of that in case it is ever lost. Here are my recovery options so far. I can perform a factory reset of Win 7 via the recovery partition I can perform a factory reset of Win 7 via burned recovery DVDs I can re-install Windows 8 cleanly from a DVD All of these are useful, but not what I want, because the first 2 methods use Win 7, and still fill the machine with crapware, and the latter doesn't provide for any post-install customisation and software installation. So, I am looking to see what other options are available to perform a Windows 8 recovery that will be more than a simple install. I am aware that Win8 comes with some useful refresh tools: Refresh your PC - Re-install Win 8 over the top of your existing installation, recovering from any Windows corruption etc. I can run this from my current install, although it says some files are missing that will be provided by me install or recovery media, which seems to be code for stick your install DVD in, and it starts after I do that - unfortunately for this particular laptop you need to specify a particular WIFI driver or the install bombs out part way through with IRQL errors, and this refresh method skips the part where you can load a driver, so it's no use to me. I think I can fix this by creating a custom recovery image using the recimg.exe command but it takes hours to complete so I haven't tried it yet. Reset your PC - Perform a full install and lose all your files. Again it needs my Install media inserting before it will do anything, but then it provides an error (will include later when I recreate it...) Now, these recovery options look useful (in principal, although both are fail for me) but they rely on having a working system to access the tools, which leads me to the last option, of making a Recovery USB drive. I have made a recovery drive, and it should perform loads of useful things, including copying my WIN7 recovery partition to the drive, providing the above refresh and reset options, providing other troubleshooting options and also the ability to restore from a custom image, only none of them seem to work for me. Creating the Recovery Drive - the option to include my recovery partition is greyed out. The partition exists and works fine, why will it not copy it? Refresh - I imagine this would have the same issues as I described before, but this is moot because when I try it says that the "drive where Windows is installed is locked, please unlock the drive and try again" with no info on what that means and how to do it. Restore - Again, probably pointless as I can just use the DVD, but it also errors: "unable to reset your PC. A required drive partition is missing" System Restore - should let me roll back a bad driver etc as per normal in Windows, only it simply says "To use system restore you must specify which windows installation to restore. Restart this computer, select an operating system, and select system restore" ?!?! System Image Recovery - this seems to be offering to restore from a Windows system image, but this is deprecated in Windows 8, although you can still make one if you use the Windows 7 Backup tools, however the resultant file is too large to put on the USB stick as it's FAT formatted, and would be a massive stack of DVDs anyway. So useless. It would be nice it it would work with the custom recovery image you can use with the refresh command, but there seems no option to do this. Automatic Repair - some diagnostics, which seem useless as it happily tells me it can't fix my problem, even though I have none. Command Prompt - yay, this works! What on earth do I want to use it for... Had any of the above worked, it might be useful, but as any form of install still requires you to have the DVD, and any form of custom recovery image also requires you to have either a massive stack of DVDs or an NTFS formatted backup device in addition to the recovery drive, it sort of ruins the point. It doesn't seem rocket science. I want to create a bootable USB drive that I can refresh Windows over an existing install with, perform a clean reinstall to a bare system, or recovery a customised image with existing apps installed. If anyone can point me in a direction that allows me to make a single recovery drive do these all these things, I would appreciate it. I have a 32Gb USB3 thumb drive that I bought for this very purpose, but it's seems to be fighting to let me do anything useful. At this rate I will be making a DriveImageXML recovery stick and dumping the OS with that, which I know works, but isn't so elegant as using the proper tools..

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  • Self-powered USB hub and power supply adapter ampere capacity

    - by galacticninja
    I am looking for a power supply adapter for my USB Hub so it can support at least 2 bus-powered external hard drives. The hub's rating is 5 volts, 2 amperes. I would like to know if it would be OK to buy a power supply adapter rated at less than 2A. I've been looking for power supply adapters and the ones that do support 2A are more expensive (more expensive than the USB hub itself) compared to those that support less than 2A. Will power supply adapter that supports less than 2A (~1-1.5A) work fine to support two external hard drives? The external hard drives are both bus-powered Western Digital My Passport Essentials 250 GB. The OS is Windows XP SP3.

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  • Windows Defender Update KB915597 (Definition 1.135.415.0)? Killed My Live Discs

    - by user88311
    Here's my problem, for those willing to read for about 2 minutes here's the entire story, http://answers.microsoft.com/en-us/windows/forum/windows_vista-windows_update/bsod-after-windows-defender-update-kb915597/a4b5fca3-0274-47b4-97c4-61b34c4c4599, for those who want the short version here's what happened. After windows update automatically updated windows defender to kb915597, my computer starting getting bsods on shut down and start up and started experiencing problems withe the usb ports. So I decided to go to the microsoft answers site for help, I know that was probably my first mistake, so I followed their advice and they turned my computer into a large paper weight. Luckily I make physical backups of my c drive every few months and I have one from back in july, so I figured I'd boot up a ubuntu live disc, copy all my files from the past 2 months to a external drive and just copy the backup back to the c drive, that's where I ran into this problem. When I put in either a ubuntu or kubuntu disc, everything goes well, until it finishes the loading bar then when the OS would presumably start up, the computer resets, I've tried with ubuntu, kubuntu and gparted, and only gparted is able to get to the point where it starts up, but even then when I try to access the internet from it, the computer resets, and when I tried to copy the entire C drive partition to a blank external I wasn't able to. So I figured somehow maybe the C drive had something to do with it, so I unplugged the C drive so my computer was just a 2.8 ghz processor and 2 gigs of ram, should have had no problem starting a live disc but the problem still continues. After doing some googling around I've found whenever windows gets a update with the title KB915597 it's pretty much the kill switch for windows, I've tried contacting microsoft tech support and even managed to directly contact a software engineer but as soon as I mention KB915597 they all just blew me off. I hope anybody who reads this has any idea how to fix this, I'm going to attempt to install ubuntu or kubuntu to a external drive using the same computer and see what happens now.

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  • What's a good Linux distro for an older PC?

    - by jdamae
    I'm new to Linux and I am interested in installing it on an older computer I have. I want to set a web server up, and install PHP and Perl on it. My PC is an older HP Pavilion a255c, with an Intel Pentium 4 processor and 512 MB of RAM. I will probably add some more memory later. This PC is more like a sandbox than anything, but I would like to get started quickly with the OS. Is there a particular flavor of Linux I would need to download because I have an old computer? I was thinking about Ubuntu, but I'm not sure what version to go with.

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  • Troubleshooting server performance with a hosted server?

    - by ProfessionalAmateur
    We are in a tough spot, we have a hosted server with the following specs: OS: Windows Server 2008 R2 Enterprise SP1 64bit Processor: Intel Xeon X7550 @ 2GHz (8 processors) RAM: 16GB The file system is on a SAN or NAS (not sure). We are seeing very odd issues where a user will open a 25MB .xslb file and it takes literally 60-120 seconds sometimes. The server is just dog slow for excel. Resources are not being pegged, CPU never jumps up, plenty of RAM... it's just oddly slow. Our host has been looking at the issue for several weeks with not much to show for it. Is there a utility I can run myself that will help trackdown our issue? I have found Server Performance Advisor V1.0 Any experience in using it? Our host is ultimately responsible for fixing this, but we are going on 1 month and our users are losing patience. Any tips would be helpful.

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  • Internet speed showing high value but never felt that speed [closed]

    - by Kiran D Pillai
    I use Reliance Netconnect+ in my Toshiba Satellite laptop. My OS is Windows 7 Ultimate. I've seen speeds up to 1500 kbps when travelling and have an average speed of 400 kbps at my room premises. I'm sorry, I've never felt that much speed while browsing or downloading. Sometimes I think some other programs are also sharing the same network. It is just showing 200 or 500 kbps but I feel 25 or 50 kbps. Is there any way to prevent them? I use Google Chrome downloaded from Google site. Please suggest me some solutions.

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  • Linux Ubuntu: Updating the GRUB menu

    - by Mr X
    So apparently there are 2 versions of Linux on my laptop(I have a dual boot system with Linux and Windows 8 but Linux is the master OS). One of them uses the Kernel version 3.11.0 whose headers + source code are incompatible with my wireless driver. My laptop is a Toshiba Satellite with a Realtek RTL8188CE wireless lan.So the newer kernel version is still the first option on the menu and to get to Linux I use the "Previous versions of linux" which is running Kernel version 3.2.0-55. What can I do to update the grub menu so that Linux version with the 3.2.0-55 Kernel appears as the primary option? Do I need to get rid of/uninstall the newer kernel version? How can I do this without screwing up Linux entirely?

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  • Snow Leopard tzdata

    - by pgb
    I live in Argentina, and our DST rules change often. So often, that major OS' tend to ship with an old version of tzdata DBs. In the past, I successfully updated the time zone databases in Tiger and Leopard. Today, however, when trying to update it in Snow Leopard, it did not work. Not only it failed, but now even after I reverted my changes, there seems to be some "cache" where the time zone information was retained. The files I updated (and reverted) are located at: /usr/share/zoneinfo and /usr/share/icu. To update those, I grabbed Apple's source code for ICU and recompiled it's database using the latest tzdata file (2010b). Then, I recompiled the tzinfo by running zic, and copied all the files to the system folders. Does anyone have experience dealing with Snow Leopard's timezone DB and can help? Thank you.

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  • How do I remove a repository of yum

    - by sunil
    When I search for a package in yum(centos 6), it tries to search in a repro named 'c6-media' And it gives a bunch of errors as follows file:///media/CentOS/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/CentOS/repodata/repomd.xml Trying other mirror. file:///media/cdrecorder/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/cdrecorder/repodata/repomd.xml Trying other mirror. file:///media/cdrom/repodata/repomd.xml: [Errno 14] Could not open/read file:///media/cdrom/repodata/repomd.xml Trying other mirror. Error: Cannot retrieve repository metadata (repomd.xml) for repository: c6-media. Please verify its path and try again Obviously the error seems to say that yum is trying to search for the CD/DVD which installed the OS. I do not have it now. All I want to do now is to delete this repository from yum. I went to the package manager graphical tool and removed this from the sources. Seems yum and the graphical tool do not use the same config. This is just my guess.

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  • iPhone Shell - is there any?

    - by alee
    While working on iphone security architecture, i came to know that i can run applications from other applications in iphone. referring to the following url http://iphonedevelopertips.com/cocoa/launching-other-apps-within-an-iphone-application.html for example, i can put a link in a website with following hyperlink skype:// will result skype to run and call at particular number. Now i have few concerns here. is there a shell running in background in iphone, so that it allows other application to run basic app commands. if the above statement is true then how can i enable or run commands directly into iphone shell? if above statements are false, then could you please explain how these commands are being executed? is this part of iPhone SDK? or this funcationality is iPhone OS

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  • Keyboard automatically disconnects and reconnects

    - by Algorithms
    The problem i am facing is the keyboard (USB) automatically disconnects when there is a fluctuation in the power supply to the speaker. The speaker and the pc both draw power from a apc ups. The fluctuation occurs because the speaker plug is not tightly connected to the ups power outlet. It is okay for normal work, but a accidental jerk causes the fluctuation. However after some amount of time (usually within 5 seconds) the keyboard automatically reconnects and windows plays the sound of hardware connected. This problem will also occur if I manually take out the speaker power cable from the ups power outlet. My question is whether the problem I am facing is due to electrical issues, or due to software problems. PC config: OS : Windows 7 Ultimate UPS : APC 600 VA PSU : Corsair TX 650 Speaker : Realtek

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  • Flash Player in Windows 7 X64 problems

    - by Flupkear
    I'm having a lot of problems with flash player in my win 7 X64 laptop, in YouTube the videos are completely black, you can only hear the sound and in Vimeo the videos are played well in normal size but completely black in fullscreen. Also some days ago YouTube played normal size videos but with controls not visible. I'm sure that the problem isn't the browser since this happen in Chrome, Firefox and IE 8. My laptop is a Dell XPS L501X, the flash version is 10,2,152,26 and the OS is Windows 7 Home Premium with SP1. I'll appreciate any help.

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  • ext4 jbd2 journaling active even on empty filesystem

    - by Paul
    I have been having several issues with my ext4 filesystems that seem to be due to jbd2 journaling. I made a related post here and am rephrasing it with the hope that someone may be able to help. For a minimal example, I start with an empty 8gb USB stick and use gparted to create one ext4 partition. The command used by gparted when creating the ext4 file system is: mkfs.ext4 -j -O extent -L DataTraveler8gb /dev/sde1 I check the filesystem with gparted: e2fsck -f -y -v /dev/sde1 and I mount it: sudo mount /dev/sde1 /media/test The disk is empty, but the journaling is very active on this disk (/dev/sde1). The other disks are ext4 SSDs formatted similarly. A snapshot of iotop: % sudo iotop -oPa Total DISK READ: 0.00 B/s | Total DISK WRITE: 2027.21 K/s PID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 262 be/3 root 0.00 B 56.00 K 0.00 % 0.18 % [jbd2/sda1-8] 29069 be/3 root 0.00 B 0.00 B 0.00 % 0.16 % [jbd2/sde1-8] 891 be/3 root 0.00 B 4.00 K 0.00 % 0.03 % [jbd2/sdc1-8] What is jbd2 doing with /dev/sde1? If I follow the same steps with a larger 2Tb disk, iotop indicates this empty disk is constantly being written to by jbd2 at the rate of Mb/s as soon as I mount it. On the other disks, which have the OS and /home, I have tried to find if any files are being modified by processes to cause this behavior but couldn't find any. I also moved many of the disk intensive process to use a tmpfs. And used noatime. I have another non-SSD hard disk on this machine, /dev/sdb, that is also ext4 but was not formatted by gparted (given to me by a coworker). It does not appear in iotop. So I am assuming there an issue with gparted. Any suggestions are appreciated. Also any tips on how to modify existing partitions to fix the issue without having to start from scratch would be great. There are some posts related to jbd2 but they didn't help (eg. here).

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  • Audio doesn't work on Windows XP guest (WS 7.0)

    - by Mads
    I can't get audio to work with on a Windows XP guest running on VMware Workstation 7.0 and Ubuntu 9.10 host. Windows fails to produce any audio output and the Windows device manager says the Multimedia Audio Controller is not working properly. Audio is working fine in the host OS. When I open Multimedia Audio Controller properties it says: Device status: The drivers for this device are not installed (Code 28) If I try to reinstall the driver I get the following error message: Cannot Install this Hardware There was a problem installing this hardware: Multimedia Audio Controller An Error occurred during the installation of the device Driver is not intended for this platform Has anyone else experienced this problem?

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  • WebLogic Server 11g with java based node manager stdout/stderr log path configuration.

    - by Mircea Vutcovici
    Hi, How I can configure the path where the stdout logs are written by the WebLogic server? I've read about -Dweblogic.log.RedirectStdoutToServerLogEnabled=true, but this redirects only part of the output. For example if I will run a thread dump, the output will remain in the original log file. I think it should be an option in nodemanager/startup.properties file. WebLogic version is 10.3.2.0 and I am using a java based node manager. OS is RHEL 5. Thank you, Mircea

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  • How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk

    - by The Geek
    We’ve covered loads of different anti-virus, Linux, and other boot disks that help you repair or recover your system, but why limit yourself to just one? Here’s how to combine your favorite repair disks together to create the ultimate repair toolkit for broken Windows systems—all on a single flash drive. The ones we’ve covered already? Here’s a quick list of all the ways you can recover your system with a rescue disk: How to Use the Avira Rescue CD to Clean Your Infected PC How to Use the BitDefender Rescue CD to Clean Your Infected PC How to Use the Kaspersky Rescue Disk to Clean Your Infected PC Change or Reset Windows Password from a Ubuntu Live CD The 10 Cleverest Ways to Use Linux to Fix Your Windows PC Change Your Forgotten Windows Password with the Linux System Rescue CD Use Ubuntu Live CD to Backup Files from Your Dead Windows Computer If you need to clean up an infected system, we’d absolutely recommend the BitDefender CD, since it’s auto-updating. Best bet? Create your ultimate boot disk with as many of the different utilities as your flash drive can hold Latest Features How-To Geek ETC How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 The 50 Best How-To Geek Windows Articles of 2010 The 20 Best How-To Geek Explainer Topics for 2010 How to Disable Caps Lock Key in Windows 7 or Vista How to Use the Avira Rescue CD to Clean Your Infected PC Luigi Installs Any OS on Google’s Cr-48 Notebook DIY iPad Stylus Offers Pen-Based Interaction on the Cheap Serene Blue Ubuntu Wallpaper for Your Desktop Enjoy Old School Style Video Game Fun with Chicken Invaders Hide the Twitter “Litter” in Twitter’s Sidebar Area (Chrome and Iron) Public Domain Day: Reflections on Copyright and the Importance of Public Domain

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  • Performance Optimization &ndash; It Is Faster When You Can Measure It

    - by Alois Kraus
    Performance optimization in bigger systems is hard because the measured numbers can vary greatly depending on the measurement method of your choice. To measure execution timing of specific methods in your application you usually use Time Measurement Method Potential Pitfalls Stopwatch Most accurate method on recent processors. Internally it uses the RDTSC instruction. Since the counter is processor specific you can get greatly different values when your thread is scheduled to another core or the core goes into a power saving mode. But things do change luckily: Intel's Designer's vol3b, section 16.11.1 "16.11.1 Invariant TSC The time stamp counter in newer processors may support an enhancement, referred to as invariant TSC. Processor's support for invariant TSC is indicated by CPUID.80000007H:EDX[8]. The invariant TSC will run at a constant rate in all ACPI P-, C-. and T-states. This is the architectural behavior moving forward. On processors with invariant TSC support, the OS may use the TSC for wall clock timer services (instead of ACPI or HPET timers). TSC reads are much more efficient and do not incur the overhead associated with a ring transition or access to a platform resource." DateTime.Now Good but it has only a resolution of 16ms which can be not enough if you want more accuracy.   Reporting Method Potential Pitfalls Console.WriteLine Ok if not called too often. Debug.Print Are you really measuring performance with Debug Builds? Shame on you. Trace.WriteLine Better but you need to plug in some good output listener like a trace file. But be aware that the first time you call this method it will read your app.config and deserialize your system.diagnostics section which does also take time.   In general it is a good idea to use some tracing library which does measure the timing for you and you only need to decorate some methods with tracing so you can later verify if something has changed for the better or worse. In my previous article I did compare measuring performance with quantum mechanics. This analogy does work surprising well. When you measure a quantum system there is a lower limit how accurately you can measure something. The Heisenberg uncertainty relation does tell us that you cannot measure of a quantum system the impulse and location of a particle at the same time with infinite accuracy. For programmers the two variables are execution time and memory allocations. If you try to measure the timings of all methods in your application you will need to store them somewhere. The fastest storage space besides the CPU cache is the memory. But if your timing values do consume all available memory there is no memory left for the actual application to run. On the other hand if you try to record all memory allocations of your application you will also need to store the data somewhere. This will cost you memory and execution time. These constraints are always there and regardless how good the marketing of tool vendors for performance and memory profilers are: Any measurement will disturb the system in a non predictable way. Commercial tool vendors will tell you they do calculate this overhead and subtract it from the measured values to give you the most accurate values but in reality it is not entirely true. After falling into the trap to trust the profiler timings several times I have got into the habit to Measure with a profiler to get an idea where potential bottlenecks are. Measure again with tracing only the specific methods to check if this method is really worth optimizing. Optimize it Measure again. Be surprised that your optimization has made things worse. Think harder Implement something that really works. Measure again Finished! - Or look for the next bottleneck. Recently I have looked into issues with serialization performance. For serialization DataContractSerializer was used and I was not sure if XML is really the most optimal wire format. After looking around I have found protobuf-net which uses Googles Protocol Buffer format which is a compact binary serialization format. What is good for Google should be good for us. A small sample app to check out performance was a matter of minutes: using ProtoBuf; using System; using System.Diagnostics; using System.IO; using System.Reflection; using System.Runtime.Serialization; [DataContract, Serializable] class Data { [DataMember(Order=1)] public int IntValue { get; set; } [DataMember(Order = 2)] public string StringValue { get; set; } [DataMember(Order = 3)] public bool IsActivated { get; set; } [DataMember(Order = 4)] public BindingFlags Flags { get; set; } } class Program { static MemoryStream _Stream = new MemoryStream(); static MemoryStream Stream { get { _Stream.Position = 0; _Stream.SetLength(0); return _Stream; } } static void Main(string[] args) { DataContractSerializer ser = new DataContractSerializer(typeof(Data)); Data data = new Data { IntValue = 100, IsActivated = true, StringValue = "Hi this is a small string value to check if serialization does work as expected" }; var sw = Stopwatch.StartNew(); int Runs = 1000 * 1000; for (int i = 0; i < Runs; i++) { //ser.WriteObject(Stream, data); Serializer.Serialize<Data>(Stream, data); } sw.Stop(); Console.WriteLine("Did take {0:N0}ms for {1:N0} objects", sw.Elapsed.TotalMilliseconds, Runs); Console.ReadLine(); } } The results are indeed promising: Serializer Time in ms N objects protobuf-net   807 1000000 DataContract 4402 1000000 Nearly a factor 5 faster and a much more compact wire format. Lets use it! After switching over to protbuf-net the transfered wire data has dropped by a factor two (good) and the performance has worsened by nearly a factor two. How is that possible? We have measured it? Protobuf-net is much faster! As it turns out protobuf-net is faster but it has a cost: For the first time a type is de/serialized it does use some very smart code-gen which does not come for free. Lets try to measure this one by setting of our performance test app the Runs value not to one million but to 1. Serializer Time in ms N objects protobuf-net 85 1 DataContract 24 1 The code-gen overhead is significant and can take up to 200ms for more complex types. The break even point where the code-gen cost is amortized by its faster serialization performance is (assuming small objects) somewhere between 20.000-40.000 serialized objects. As it turned out my specific scenario involved about 100 types and 1000 serializations in total. That explains why the good old DataContractSerializer is not so easy to take out of business. The final approach I ended up was to reduce the number of types and to serialize primitive types via BinaryWriter directly which turned out to be a pretty good alternative. It sounded good until I measured again and found that my optimizations so far do not help much. After looking more deeper at the profiling data I did found that one of the 1000 calls did take 50% of the time. So how do I find out which call it was? Normal profilers do fail short at this discipline. A (totally undeserved) relatively unknown profiler is SpeedTrace which does unlike normal profilers create traces of your applications by instrumenting your IL code at runtime. This way you can look at the full call stack of the one slow serializer call to find out if this stack was something special. Unfortunately the call stack showed nothing special. But luckily I have my own tracing as well and I could see that the slow serializer call did happen during the serialization of a bool value. When you encounter after much analysis something unreasonable you cannot explain it then the chances are good that your thread was suspended by the garbage collector. If there is a problem with excessive GCs remains to be investigated but so far the serialization performance seems to be mostly ok.  When you do profile a complex system with many interconnected processes you can never be sure that the timings you just did measure are accurate at all. Some process might be hitting the disc slowing things down for all other processes for some seconds as well. There is a big difference between warm and cold startup. If you restart all processes you can basically forget the first run because of the OS disc cache, JIT and GCs make the measured timings very flexible. When you are in need of a random number generator you should measure cold startup times of a sufficiently complex system. After the first run you can try again getting different and much lower numbers. Now try again at least two times to get some feeling how stable the numbers are. Oh and try to do the same thing the next day. It might be that the bottleneck you found yesterday is gone today. Thanks to GC and other random stuff it can become pretty hard to find stuff worth optimizing if no big bottlenecks except bloatloads of code are left anymore. When I have found a spot worth optimizing I do make the code changes and do measure again to check if something has changed. If it has got slower and I am certain that my change should have made it faster I can blame the GC again. The thing is that if you optimize stuff and you allocate less objects the GC times will shift to some other location. If you are unlucky it will make your faster working code slower because you see now GCs at times where none were before. This is where the stuff does get really tricky. A safe escape hatch is to create a repro of the slow code in an isolated application so you can change things fast in a reliable manner. Then the normal profilers do also start working again. As Vance Morrison does point out it is much more complex to profile a system against the wall clock compared to optimize for CPU time. The reason is that for wall clock time analysis you need to understand how your system does work and which threads (if you have not one but perhaps 20) are causing a visible delay to the end user and which threads can wait a long time without affecting the user experience at all. Next time: Commercial profiler shootout.

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  • Aptana Under linux

    - by fatnjazzy
    Hey, I downloaded the Aptanastudio 2.0 and unzipped it in the desktop. Im trying to run Aptana studio 2.0 under OpenSuse 11 and i get the following error... Any idea y? Thanks JVM terminated. Exit code=-1 -Xms40m -Xmx384m -Djava.awt.headless=true -XX:MaxPermSize=256m -Djava.class.path=/home/avi/Desktop/Aptana Studio 2.0/plugins/org.eclipse.equinox.launcher_1.0.200.v20090520.jar -os linux -ws gtk -arch x86 -showsplash -launcher /home/avi/Desktop/Aptana Studio 2.0/AptanaStudio -name AptanaStudio --launcher.library /home/avi/Desktop/Aptana Studio 2.0/plugins/org.eclipse.equinox.launcher.gtk.linux.x86_1.0.200.v20090520/eclipse_1206.so -startup /home/avi/Desktop/Aptana Studio 2.0/plugins/org.eclipse.equinox.launcher_1.0.200.v20090520.jar -application com.aptana.ide.desktop.integration.Application -vm /usr/lib/jvm/java-1.6.0-openjdk-1.6.0/jre/bin/../lib/i386/client/libjvm.so -vmargs -Xms40m -Xmx384m -Djava.awt.headless=true -XX:MaxPermSize=256m -Djava.class.path=/home/avi/Desktop/Aptana Studio 2.0/plugins/org.eclipse.equinox.launcher_1.0.200.v20090520.jar

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  • Redirect example.com to www.example.com VPS & Apache2

    - by Thomas Buckley
    I have a VPS and a domain name registered with the provider. When I enter www.example.com my site is displayed correctly, but entering example.com does not work. I am able to ping www.example.com. I added the following line to my apache2 default vhosts file: ServerName example.com ServerAlias www.example.com But this did not work. The VPS is a Debian5 OS. Any ideas? Note: There is no option via a provided control panel to add this, it's a basic package I purchased I know this post answers it but there are no extra comments and I'd like to know if it's the best way: way to redirect page to www using virtual host configuration in sites-available for apache2? Thanks

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  • USB Thumb Drive not recognized in Hyper-V Manager

    - by Vazgen
    I have the free, standalone core Hyper-V Server 2012 running on my physical machine. I set up remote management from my Windows 8 client. When I proceed to create a virtual machine I would like to install the OS from a usb thumb drive but it is not recognized in Hyper-V Manager on my client (when the USB is plugged into the physical server) nor is it recognized in Server Manager under File and Storage Services Volumes Is there a role needed to recognize external usb flash drives? Because I think this standalone version is just core Hyper-V role and that's it... but this is such a basic functionality. Can anybody comment.

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  • Tools to test multicast routing

    - by Zoredache
    I am looking for a good simple tool that runs on a standard OS (Windows or Linux) that I can used to test that multicast is being passed properly by a router. I have been asked by a client to enable multicast routing on a Linux box acting as their router since their phone system requires multicast to for a few features. Since I am not physically near the client I don't really have the ability to experiment with the various methods for setting up multicast routing on Linux. I can setup a router at my desk that is identical to what is deployed on their network, but I don't know of any good simple tools that I can use to generate or listen for multicast traffic. The one mulicast tool I have found is mcast.exe tool which is part of the Windows 2000/2003 resource kit. From what I have read online it seems that mcast.exe does not work across a router, and only works on the local network, so that doesn't seem to be useful for me to test multicast routing. So what do tool(s) do you use to test that multicast routing is properly setup?

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  • SharpDX and game engines, back to zero?

    - by Baboon
    I'm a desktop developer (I mainly do WPF for a living) but I want to make games as a hobby. So a few months ago, I started reading blogs, gamedevSE, you name it. I understand in the C++ DirectX world, you have engines such as Unity3D with designers and whatnot, but as much as I'm ok to spend months understanding game development, I'd prefer to stay with my comfy C#. So I thought I'd develop my first games in /C#/DirectX through SharpDX But then, I can't use game engines anymore, since they're made for C++DirectX and not SharpDX. (ok, I could do P/Invokes but that defeats the purpose of SharpDX). I do know about XNA, and I also do know I can't publish to the marketplace with it (and quite frankly, I don't really want to learn an API that is in jeopardy). So how do you conceal writing games in C# and using existing game engines instead of reinventing the wheel? wait for ports? So I've found out the following: After doing the first tutorials of MOgre and digging around, it seems MOgre gives you the worse of both worlds: . You can't port it with Mono because it directly references a C++/CLI dll (Ogre) and C++/CLI isn't supported by Mono. And since it's not C++ itself, you can't make a pure build. Which, as far as I understand, means I'd be stuck on windows (and not even WinRT/Metro compatible), without capability of porting anything to mobiles or other OS (Mac/Linux). Even though it looks really nice to develop with MOgre, I'd like to learn something a little more open to future broadening. On the other hand, MonoGame seems to be a rewrite of XNA with SharpDX which sounds very promising: Mono allows me to easily port my games to other platforms, mobiles included. SharpDX allows me to access the latest DirectX versions XNA would be my first choice if only MS showed some hope for the future It really looks like MonoGame is nothing else than XNA on SharpDX. Axiom looks good too but I lack info on the subject (and pages with poor design don't give me a good feeling about an API...) XNA with SunBurn looks good: It should be portable to Mono (can anyone with experience give us feedback on that?), thus multi-platform. It's then marketplace-able since Mono itself is. Did I miss something or are 2) and 4) my best options (aside from the fact Mono doesn't support any XAML)?

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