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  • How to debug slow queries in Django+Postgres

    - by lacker
    My database queries from Django are starting to take 1-2 seconds and I'm having trouble figuring out why. Not too big a site, about 1-2 requests per second (that hit Django; static files are just served from nginx.) The thing that confuses me is, I can replicate the slowness in the Django shell using debug mode. But when I issue the exact same queries at an sql prompt they are fast. It takes about a second for a query to return, but when I check connection.queries it reports the time as under 10 ms. Here's an example (from the Django shell): >>> p = PlayerData.objects.get(uid="100000521952372") >>> a = time.time(); p.save(); print time.time() - a 1.96812295914 >>> for d in connection.queries: print d["time"] ... 0.002 0.000 0.000 How can I figure out where this extra time is being spent? I'm using Apache+mod_wsgi in daemon mode, but this happens with just the django shell as well, so I figure it is not apache-related.

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  • Browser says "Waiting for www.xyz.com" for a very long time

    - by Phil
    When I load my website (hosted with Ipage). The browser often takes an incredible long time saying "Waiting for www.xyz.com ..." before any elements of the site actually appear. After this "Waiting for" process, the text, images and everything else actually load quite fast. I contacted my host with my tracert result and they said they optimized my website database and increased the memory available to PHP on my account to 64 Mb.They also said they have checked the issue by accessing my website and found that it is loading fine without any slowness. It seems to be a temporary issue. Please try to access your website with different browser and network. I tried different browsers and networks but this "Waiting for" process always takes too long. My website is http://www.surreyextra.com/ . It's Wordpress and BuddyPress. I'm in the UK while Ipage host is placed in the USA, can this potentially be a problem? I have tried a number of optimizations, like minifying my CSS and JS files and use catching but the problem hasn't improved. So is it my host's fault, should I contact them again?

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  • Most scalable way of serving a small set of static HTTP content

    - by Ekevoo
    The story: Hi guys. I'm among the people responsible for serving the results of the most anticipated (by number of people participating) annual entrance exam in my state. As such, when our results are published, the interest is overwhelming. In the past we delegated the responsibility of serving the results to the media, but that spoils a little the officialness of these results. This year we went with a little (long overdue) experiment of using lighttpd instead of Apache as well as other physical network optimizations I wasn't directly involved with. The results were very satisfactory. The server didn't choke even once, nor we saw any of the usual Twitter complaints on unavailability and/or slowness that were previously common. However, because we still delegated the first publication of the results to the media I'm still not 100% sure we can handle the load of actually publishing the results first. The question: Now because these files are like 14MB in total and a true lightweight Linux distribution isn't that big either, I'm thinking: what if next year we run full RAMdrive? Is there any? Is that useful? Is that worth it for a team that uses Debian almost exclusively? Are there other optimizations that I should be focusing on instead?

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  • Where do these mysterious DNS lookups come from and why are they slow?

    - by Hongli
    I have recently obtained a new dedicated server which I'm now setting up. It's running on 64-bit Debian 6.0. I have cloned a fairly large git repository (177 MB including working files) onto this server. Switching to a different branch is very very slow. On my laptop it takes 1-2 seconds, on this server it can take half a minute. After some investigation it turns out to be some kind of DNS timeout. Here's an exhibit from strace -s 128 git checkout release: stat("/etc/resolv.conf", {st_mode=S_IFREG|0644, st_size=132, ...}) = 0 socket(PF_INET, SOCK_DGRAM|SOCK_NONBLOCK, IPPROTO_IP) = 5 connect(5, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("213.133.99.99")}, 16) = 0 poll([{fd=5, events=POLLOUT}], 1, 0) = 1 ([{fd=5, revents=POLLOUT}]) sendto(5, "\235\333\1\0\0\1\0\0\0\0\0\0\35Debian-60-squeeze-64-minimal\n\17happyponies\3com\0\0\1\0\1", 67, MSG_NOSIGNAL, NULL, 0) = 67 poll([{fd=5, events=POLLIN}], 1, 5000) = 0 (Timeout) This snippet repeats several times per 'git checkout' call. My server's hostname was originally Debian-60-squeeze-64-minimal. I had changed it to shell.happyponies.com by running hostname shell.happyponies.com, editing /etc/hostname and rebooting the server. I don't understand the DNS protocol, but it looks like Git is trying to lookup the IP for Debian-60-squeeze-64-minimal as well as for happyponies.com. Why does Debian-60-squeeze-64-minimal come back even though I've already changed the host name? Why does Git perform DNS lookups at all? Why are these lookups so slow? I've already verified that all DNS servers in /etc/resolv.conf are up and responding slowly, yet Git's own lookups time out. Changing the host name back to Debian-60-squeeze-64-minimal seems to fix the slowness. Basically I just want to fix whatever DNS issues my server has because I'm sure they will cause more problems that just slowing down git checkout. But I'm not sure sure what the problem exactly is and what these symptoms mean.

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  • System Center 2012 VMM UI is very slow

    - by Grant
    I've recently setup system center 2012 a new server 2008 r2 server which I'm using for virtual machines. Everything seems to be working fine, and the virtual machines are nice and fast. But the Virtual Machine Manager interface is always excruciatingly slow. Sometimes taking up to 15 seconds moving between screens. It's very frustrating trying to use it when a task that just involves a couple clicks ends up taking several minutes. Pages that have a lot of form fields seem to take the longest to load - such as the page to change hardware settings of a virtual machine. Is this just normal performance for VMM? If not, where can I look to find what is slowing it down. Nothing else on the system seems to suffer. I can load and use Hyper-V manager with no noticable slowness. Even programs like event viewer that are usually rather slow seem to load fairly fast. Only the system center programs seem slow. Server is a Dell R710, 2x16 core opteron 6274 processors, 96GB RAM. OS drive is 2x500GB 7.2k RPM SAS drives in RAID1 (opted for the less expensive 7.2k drives since pretty much everything is stored on the SAN). Am I just being impatient? Does anyone else use VMM 2012 and find it slow?

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  • TortoiseSVN client slows Explorer to a crawl in Windows XP running in Parallels

    - by Cory Larson
    I thought I'd make my first SuperUser question relatively simple, though it's the kind of question that may not get many responses as I'm not directly involved with the issue. A colleague does his development in Windows XP running in Parallels on his Mac. We've just migrated our VSS repository to SVN, and we've gone with TortoiseSVN as our client of choice with the Ankhsvn plugin for Visual Studio. On his XP instance, after installing TortoiseSVN, browsing through folders using Explorer is extremely slow; about 15 - 30 seconds before the contents of the next folder displays. It's the slowest when opening My Computer. Once he reaches a folder that contains the working content of an SVN project, Explorer behaves quickly again as expected. It seems that TortoiseSVN may be spending a bunch of time searching subfolders for stuff so it can do its icon-overlay thing, but that's just a guess. I've used TortoiseSVN for years on both XP and Vista on far less powerful machines without any issues with Explorer, so I'm attributing the slowness to it being run in a VM, though that may not be the actual issue. So has anyone encountered similar performance issues, and/or know of a fix? Keep in mind that any requests to make changes to his configuration will need to be communicated and thus my response time might be slow. Thanks everyone!

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  • Ubuntu inside VirtualBox is slow

    - by Kapsh
    I am running an Ubuntu instance on VirtualBox inside XP. Here are the details: Host: Windows XP Pro Guest: Ubuntu 8.10 Total RAM: 3GB RAM For VM: 1GB Total Video Memory: 128MB Video Memory for VM: 40MB Hard Drive: 200GB Hard Drive for VM: 30GB Processor: 2.80GHz Core Duo The problem is that whenever I am inside the virtual machine, things seem so much slower in general. For example Firefox, Eclipse take longer to load, dragging windows show a lag etc. I have tried running Ubuntu before (not inside a VM) and it seemed fantastically fast. So I am disappointed to have to deal with this situation. But I need access to the XP partition without having to reboot and hence the attempt. I am surprised with the perceived slowness since the whole world seems to be doing virtualization and I cannot imagine everyone works on slow systems knowingly. My question is - is there something I should be doing to boost performance? Am I doing something wrong? This is my home machine and I am not sure if this is the right forum to ask. Thanks.

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  • BackupExec 12 + RALUS - VERY slow backups

    - by LVDave
    We use Backup Exec 12 and the Remote Agent for Linux/Unix Servers (RALUS) to backup a large RHEL5 system. For various reasons we need to do a daily working set job. These working-set jobs run abysmally slow. The link between the target machine and the BE server is gigabit, and any other type of job runs 1-3GB/min. These working-set jobs start out at perhaps 40MB/min and over the course of the backup job slowly drops down so low that the BE job rate display in the "current jobs" goes blank.. Since we usually are only doing changed-files for one day, the job is usually small and finishes overnight and we don't worry abotu the slowness, but we had some issues with the backup server, and missed about 6 days of fairly heavy work on the Linux box, so this working-set job will be a doozy.. We have support with Symantec, and I've pestered them a lot about this, they've had me run RALUS in debug mode, sent them that log and a VXgather from the BE host and they had no fix/workaround.. To give an idea, I have the mentioned working-set job running for the last 3 1/2 hours and it's backed up just under 10MEGAbytes.... I'm posting this here to see if anybody in the "real world" has seen this/and/or has any ideas what might be causing these abysmally slow jobs, since Symantec seems to be clueless...

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  • Load Balancing is unusual in Apache in round-robin mode when one of the tomcat is brought down

    - by srayker
    We are facing a unusual behavior with round-robin load balancing on apache when one of the tomcat server is brought down. Our Setup: we have 2 apache web servers on the front end using mod_jk module for load balancing using round robin for load distribution. We also have enabled session stickyness. This is followed by 4 tomcat servers on which the applications are running. Sometimes under heavy load, if there is a slowness in our DB tier we find that eventually one of the tomcat goes into a hung state and would need a restart. The moment we bounce the tomcat we see a spike in requests in one of the server and this would also go into hung state and need a restart. Eventually all the server will face similar condition. What beats me is why does the Apache transfer the whole load to one server instead of distributing the load. We are now trying the worker.balancer.method=B to see if this helps to resolve our issue. Any thoughts on resolving the issue is greatly appreciated. regards, srayker

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  • Some VS 2010 RC Updates (including patches for Intellisense and Web Designer fixes)

    - by ScottGu
    [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] We are continuing to make progress on shipping Visual Studio 2010.  I’d like to say a big thank you to everyone who has downloaded and tried out the VS 2010 Release Candidate, and especially to those who have sent us feedback or reported issues with it. This data has been invaluable in helping us find and fix remaining bugs before we ship the final release. Last month I blogged about a patch we released for the VS 2010 RC that fixed a bad intellisense crash issue.  This past week we released two additional patches that you can download and apply to the VS 2010 RC to immediately fix two other common issues we’ve seen people run into: Patch that fixes crashes with Tooltip invocation and when hovering over identifiers The Visual Studio team recently released a second patch that fixes some crashes we’ve seen when tooltips are displayed – most commonly when hovering over an identifier to view a QuickInfo tooltip. You can learn more about this issue from this blog post, and download and apply the patch here. Patch that fixes issues with the Web Forms designer not correctly adding controls to the auto-generated designer files The Visual Web Developer team recently released a patch that fixes issues where web controls are not correctly added to the .designer.cs file associated with the .aspx file – which means they can’t be programmed against in the code-behind file.  This issue is most commonly described as “controls are not being recognized in the code-behind” or “editing existing .aspx files regenerates the .aspx.designer.(vb or cs) file and controls are now missing” or “I can’t embed controls within the Ajax Control Toolkit TabContainer or the <asp:createuserwizard> control”. You can learn more about the issue here, and download the patch that fixes it here. Common Cause of Intellisense and IDE sluggishness on Windows XP, Vista, Win Server 2003/2008 systems Over the last few months we’ve occasionally seen reports of people seeing tremendous slowness when typing and using intellisense within VS 2010 despite running on decent machines.  It took us awhile to track down the cause – but we have found that the common culprit seems to be that these machines don’t have the latest versions of the UIA (Windows Automation) component installed. UIA 3 ships with Windows 7, and is a recommended Windows Update patch on XP and Vista (which is why we didn’t see the problem in our tests – since our machines are patched with all recommended updates).  Many systems (especially on XP) don’t automatically install recommended updates, though, and are running with older versions of UIA. This can cause significant performance slow-downs within the VS 2010 editor when large lists are displayed (for example: with intellisense). If you are running on Windows XP, Vista, or Windows Server 2003 or 2008 and are seeing any performance issues with the editor or IDE, please install the free UIA 3 update that can be downloaded from this page.  If you scroll down the page you’ll find direct links to versions for each OS. Note that we are making improvements to the final release of VS 2010 so that we don’t have big perf issues when UIA 3 isn’t installed – and we are also adding a message within the IDE that will warn you if you don’t have UIA 3 installed and accessibility is activated. Improved Text Rendering with WPF 4 and VS 2010 We recently made some nice changes to WPF 4 which improve the text clarity and text crispness over what was in the VS 2010/.NET 4 Release Candidate.  In particular these changes improve scenarios where you have a dark background with light text. You can learn more about these improvements in this WPF Team blog post.  These changes will be in the final release of VS 2010 and .NET 4. Hope this helps, Scott

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  • IntelliTrace As a Learning Tool for MVC2 in a VS2010 Project

    - by Sam Abraham
    IntelliTrace is a new feature in Visual Studio 2010 Ultimate Edition. I see this valuable tool as a “Program Execution Recorder” that captures information about events and calls taking place as soon as we hit the VS2010 play (Start Debugging) button or the F5 key. Many online resources already discuss IntelliTrace and the benefit it brings to both developers and testers alike so I see no value of just repeating this information.  In this brief blog entry, I would like to share with you how I will be using IntelliTrace in my upcoming talk at the Ft Lauderdale ArcSig .Net User Group Meeting on April 20th 2010 (check http://www.fladotnet.com for more information), as a learning tool to demonstrate the internals of the lifecycle of an MVC2 application.  I will also be providing some helpful links that cover IntelliTrace in more detail at the end of my article for reference. IntelliTrace is setup by default to only capture execution events. Microsoft did such a great job on optimizing its recording process that I haven’t even felt the slightest performance hit with IntelliTrace running as I was debugging my solutions and projects.  For my purposes here however, I needed to capture more information beyond execution events, so I turned on the option for capturing calls in addition to events as shown in Figures 1 and 2. Changing capture options will require us to stop our debugging session and start over for the new settings to take place. Figure 1 – Access IntelliTrace options via the Tools->Options menu items Figure 2 – Change IntelliTrace Options to capture call information as well as events Notice the warning with regards to potentially degrading performance when selecting to capture call information in addition to the default events-only setting. I have found this warning to be sure true. My subsequent tests showed slowness in page load times compared to rendering those same exact pages with the “event-only” option selected. Execution recording is auto-started along with the new debugging session of our project. At this point, we can simply interact with the application and continue executing normally until we decide to “playback” the code we have executed so far.  For code replay, first step is to “break” the current execution as show in Figure 3.   Figure 3 – Break to replay recording A few tries later, I found a good process to quickly find and demonstrate the MVC2 page lifecycle. First-off, we start with the event view as shown in Figure 4 until we find an interesting event that needs further studying.  Figure 4 – Going through IntelliTrace’s events and picking as specific entry of interest We now can, for instance, study how the highlighted HTTP GET request is being handled, by clicking on the “Calls View” for that particular event. Notice that IntelliTrace shows us all calls that took place in servicing that GET request. Double clicking on any call takes us to a more granular view of the call stack within that clicked call, up until getting to a specific line of code where we can do a line-by-line replay of the execution from that point onwards using F10 or F11 just like our typical good old VS2008 debugging helped us accomplish. Figure 5 – switching to call view on an event of interest Figure 6 – Double clicking on call shows a more granular view of the call stack. In conclusion, the introduction of IntelliTrace as a new addition to the VS developers’ tool arsenal enhances development and debugging experience and effectively tackles the “no-repro” problem. It will also hopefully enhance my audience’s experience listening to me speaking about  an MVC2 page lifecycle which I can now easily visually demonstrate, thereby improving the probability of keeping everybody awake a little longer. IntelliTrace References: http://msdn.microsoft.com/en-us/magazine/ee336126.aspx http://msdn.microsoft.com/en-us/library/dd264944(VS.100).aspx

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  • Tough Decisions

    - by Johnm
    There was once a thriving business that employed two Database Administrators, Sam and Jim. Both DBAs were certified, educated and highly talented in their skill sets. During lunch breaks these two DBAs were often found together discussing best practices, troubleshooting techniques and the latest release notes for the upcoming version of SQL Server. They genuinely loved what they did. The maintenance of the first database was the responsibility of Sam. He was the architect of this server's setup and he was very meticulous in its configuration. He regularly monitored the health of the database, validated backup files and regularly adhered to the best practices that were advocated by well respected professionals. He was very proud of the fact that there was never a database that he managed that lost data or performed poorly. The maintenance of the second database was the responsibility of Jim. He too was the architect of this server's setup. At the time that he built this server, his understanding of the finer details of configuration were not as clear as they are today. The server was build on a shoestring budget and with very little time for testing and implementation. Jim often monitored the health of the database; but in more of a reactionary mode due to user complaints of slowness or failed transactions. Deadlocks abounded and the backup files were never validated. One day, the announcement was made that revealed that the business had hit financially hard times. Budgets were being cut, limitation on spending was implemented and the reduction in full-time staff was required. Since having two DBAs was regarded a luxury by many, this meant that either Sam or Jim were about to find themselves out of a job. Sam and Jim's boss, Frank, was faced with a very tough decision. Sam's performance was flawless. His techniques and practices were perfection. The databases he managed were reliable and efficient. His solutions are "by the book". When given a task it is certain that, while it may take a little longer, it will be done right the first time. Jim's techniques and practices were not perfect; but effective and responsive. He made mistakes regularly; but he shows that he learns from them and they often result in innovative solutions. When given a task it is certain that, while the results may require some tweaking, it will be done on time and under budget. You are Frank's best friend. He approaches you and presents this scenario. He must layoff one of his valued DBAs the very next morning. Frank asks you: "All else being equal, who would you let go? and Why?" Another pertinent question is raised: "Regardless of good times or bad, if you had to choose, which DBA would you want on your team when tough challenges arise?" Your response is. (This is where you enter a comment below)

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  • TechEd Israel 2010 may only accept speakers from sponsors

    - by RoyOsherove
    A month or so ago, Microsoft Israel started sending out emails to its partners and registered event users to “Save the date!” – Micraoft Teched Israel is coming, and it’s going to be this november! “Great news” I thought to myself. I’d been to a couple of the MS teched events, as a speaker and as an attendee, and it was lovely and professionally done. Israel is an amazing place for technology and development and TechEd hosted some big names in the world of MS software. A couple of weeks ago, I was shocked to hear from a couple of people that Microsoft Israel plans to only accept non-MS teched speakers, only from sponsors of the event. That means that according to the amount that you have paid, you get to insert one or more of your own selected speakers as part of teched. I’ve spent the past couple of weeks trying to gather more evidence of this, and have gotten some input from within MS about this information. It looks like that is indeed the case, though no MS rep. was prepared to answer any email I had publicly. If they approach me now I’d be happy to print their response. What does this mean? If this is true, it means that Microsoft Israel is making a grave mistake – They are diluting the quality of the speakers for pure money factors. That means, that as a teched attendee, who paid good money, you might be sitting down to watch nothing more that a bunch of infomercials, or sub-standard speakers – since speakers are no longer selected on quality or interest in their topic. They are turning the conference from a learning event to a commercial driven event They are closing off the stage to the community of speakers who may not be associated with any organization  willing to be a sponsor They are losing speakers (such as myself) who will not want to be part of such an event. (yes – even if my company ends up sponsoring the event, I will not take part in it, Sorry Eli!) They are saying “F&$K you” to the community of MVPs who should be the people to be approached first about technical talks (my guess is many MVPs wouldn’t want to talk at an event driven that way anyway ) I do hope this ends up not being true, but it looks like it is. MS Israel had already done such a thing with the Developer Days event previouly held in Israel – only sponsors were allowed to insert speakers into the event. If this turns out to be true I would urge the MS community in Israel to NOT TAKE PART AT THIS EVENT in any form (attendee, speaker, sponsor or otherwise). by taking part, you will be telling MS Israel it’s OK to piss all over the community that they are quietly suffocating anyway. The MVP case MS Israel has managed to screw the MVP program as well. MS MVPs (I’m one) have had a tough time here in Israel the past couple of years. ever since yosi taguri left the blue badge ranks, there was not real community leader left. Whoever runs things right now has their eyes and minds set elsewhere, with the software MVP community far from mind and heart. No special MVP events (except a couple of small ones this year). No real MVP leadership happens here, with the MVP MEA lead (Ruari) being on a remote line, is not really what’s needed. “MVP? What’s that?” I’m sure many MS Israel employees would say. Exactly my point. Last word I’ve been disappointed by the MS machine for a while now, but their slowness to realize what real community means in the past couple of years really turns me off. Maybe it’s time to move on. Maybe I shouldn’t be chasing people at MS Israel begging for a room to host the Agile Israel user group. Maybe it’s time to say a big bye bye and start looking at a life a bit more disconnected.

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  • Heterogeneous Datacenter Management with Enterprise Manager 12c

    - by Joe Diemer
    The following is a Guest Blog, contributed by Bryce Kaiser, Product Manager at Blue MedoraWhen I envision a perfect datacenter, it would consist of technologies acquired from a single vendor across the entire server, middleware, application, network, and storage stack - Apps to Disk - that meets your organization’s every IT requirement with absolute best-of-breed solutions in every category.   To quote a familiar motto, your datacenter would consist of "Hardware and Software, Engineered to Work Together".  In almost all cases, practical realities dictate something far less than the IT Utopia mentioned above.   You may wish to leverage multiple vendors to keep licensing costs down, a single vendor may not have an offering in the IT category you need, or your preferred vendor may quite simply not have the solution that meets your needs.    In other words, your IT needs dictate a heterogeneous IT environment.  Heterogeneity, however, comes with additional complexity. The following are two pretty typical challenges:1) No End-to-End Visibility into the Enterprise Wide Application Deployment. Each vendor solution which is added to an infrastructure may bring its own tooling creating different consoles for different vendor applications and platforms.2) No Visibility into Performance Bottlenecks. When multiple management tools operate independently, you lose diagnostic capabilities including identifying cross-tier issues with database, hung-requests, slowness, memory leaks and hardware errors/failures causing DB/MW issues. As adoption of Oracle Enterprise Manager (EM) has increased, especially since the release of Enterprise Manager 12c, Oracle has seen an increase in the number of customers who want to leverage their investments in EM to manage non-Oracle workloads.  Enterprise Manager provides a single pane of glass view into their entire datacenter.  By creating a highly extensible framework via the Oracle EM Extensibility Development Kit (EDK), Oracle has provided the tooling for business partners such as my company Blue Medora as well as customers to easily fill gaps in the ecosystem and enhance existing solutions.  As mentioned in the previous post on the Enterprise Manager Extensibility Exchange, customers have access to an assortment of Oracle and Partner provided solutions through this Exchange, which is accessed at http://www.oracle.com/goto/emextensibility.  Currently, there are over 80 Oracle and partner provided plug-ins across the EM 11g and EM 12c versions.  Blue Medora is one of those contributing partners, for which you will find 3 of our solutions including our flagship plugin for VMware.  Let's look at Blue Medora’s VMware plug-in as an example to what I'm trying to convey.  Here is a common situation solved by true visibility into your entire stack:Symptoms•    My database is bogging down, however the database appears okay internally.  Maybe it’s starved for resources?•    My OS tooling is showing everything is “OK”.  Something doesn’t add up. Root cause•    Through the VMware plugin we can see the problem is actually on the virtualization layer Solution•    From within Enterprise Manager  -- the same tool you use for all of your database tuning -- we can overlay the data of the database target, host target, and virtual machine target for a true picture of the true root cause. Here is the console view: Perhaps your monitoring conditions are more specific to your environment.  No worries, Enterprise Manager still has you covered.  With Metric Extensions you have the “Next Generation” of User-Defined Metrics, which easily bring the power of your existing management scripts into a single console while leveraging the proven Enterprise Manager framework. Simply put, Oracle Enterprise manager boasts a growing ecosystem that provides the single pane of glass for your entire datacenter from the database and beyond.  Bryce can be contacted at [email protected]

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  • Very slow performance deserializing using datacontractserializer in a Silverlight Application.

    - by caryden
    Here is the situation: Silverlight 3 Application hits an asp.net hosted WCF service to get a list of items to display in a grid. Once the list is brought down to the client it is cached in IsolatedStorage. This is done by using the DataContractSerializer to serialize all of these objects to a stream which is then zipped and then encrypted. When the application is relaunched, it first loads from the cache (reversing the process above) and the deserializes the objects using the DataContractSerializer.ReadObject() method. All of this was working wonderfully under all scenarios until recently with the entire "load from cache" path (decrypt/unzip/deserialize) taking hundreds of milliseconds at most. On some development machines but not all (all machines Windows 7) the deserialize process - that is the call to ReadObject(stream) takes several minutes an seems to lock up the entire machine BUT ONLY WHEN RUNNING IN THE DEBUGGER in VS2008. Running the Debug configuration code outside the debugger has no problem. One thing that seems to look suspicious is that when you turn on stop on Exceptions, you can see that the ReadObject() throws many, many System.FormatException's indicating that a number was not in the correct format. When I turn off "Just My Code" thousands of these get dumped to the screen. None go unhandled. These occur both on the read back from the cache AND on a deserialization at the conclusion of a web service call to get the data from the WCF Service. HOWEVER, these same exceptions occur on my laptop development machine that does not experience the slowness at all. And FWIW, my laptop is really old and my desktop is a 4 core, 6GB RAM beast. Again, no problems unless running under the debugger in VS2008. Anyone else seem this? Any thoughts? Here is the bug report link: https://connect.microsoft.com/VisualStudio/feedback/details/539609/very-slow-performance-deserializing-using-datacontractserializer-in-a-silverlight-application-only-in-debugger

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  • Running Magento for multiple clients - single Installaton vs. multiple installations

    - by Chris Hopkins
    Hi There I am looking to set-up a Magento (Community Edition) installation for multiple clients and have researched the matter for a few days now. I can see that the Enterprise Edition has what I need in it, but surprisingly I am not willing to shell out the $12,000 odd yearly subscription. It seems there are a few options available to be but I am worried about the performance I will get out of the various options. Option 1) Single install using AITOC advanced permissions module So this is really what I am after; one installation so that I can update my core files all at the same time and also manage all my store users from one place. The problems here are that I don't know anything about the reliability of this extra product and that I have to pay a bit extra. I am also worried that if I have 10 stores running off this one installation it might all slow down so much and keel over as I have heard allot about Magento's slowness. Module Link: http://www.aitoc.com/en/magentomods_advanced_permissions.html Option 2) Multiple installations of Magento on one server for each shop So here I have 10 Magento installations on one server all running happily away not using any extra money, but I now have 10 separate stores to update and maintain which could be annoying. Also I haven't been able to find a whole lot of other people using this method and when I have they are usually asking how to stop their servers from dying. So this route seems like it could be even worse on my server as I will have more going on on my server but if my server could take it each Magento installation would be simpler and less likely to slow down due to each one having to run 10 shops on its own? Option 3) Use lots of servers and lots of Magento installations I just so do not want to do this. Option 4) Buy Magento Enterprise I do not have the money to do this. So which route is less likely to blow up my server? And does anyone have experience with this holy grail of a module? Thanks for reading and thanks in advance for any help - Chris Hopkins

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  • Query optimization (OR based)

    - by john194
    I have googled but I can't find answers for these questions. Your advice is appreciated. centOS on vps with 512MB RAM, nginx, php5 (fastcgi), mysql5 (myisam, not innodb). I need to optimize this app created by some ex-employee. This app is working, but it's slow. Table: t1(id[bigint(20)],c1[mediumtext],c2[mediumtext],c3[mediumtext],c4[mediumtext]) id is some random big number, and is PK Those mediumtext rows look like this: c1="|box-002877|" c2="|ct-2348|rd-11124854|hw-3949|wd-8872|hw-119037736|...etc.. " c3="|fg-2448|wd-11172|hw-1656|...etc.. " c4="|hg-2448|qd-16667|...etc." (some columns contain a lot of data, around 900 KiB, database around 300 MiB) Yes, mediumtext "is bad", and (20) is too big... but I didn't create this. Those codes can be found on any of those 4 mediumtext's... //he needs all the columns of the row containing $code, so he wrote this: function f1($code) { SELECT * FROM t1 WHERE c1 LIKE '%$code%' OR c2 LIKE '%$code%' OR c3 LIKE '%$code%' OR c4 LIKE '%$code%'; Questions: Q1. If $code is found on c1... mysql automatically stops checking and returns row=id+c1+c2+c3+c4? or it will continue (wasting time) checking c2, c3 and c4?... Q2. Mysql is working with this table on disk (not RAM) because of the mediumtext, right? is this the primary cause of slowness? Q3. That query can be cached by mysql (if using a big query_cache_size=128M value on the my.cnf)? or that's not cacheable due to the mediumtexts, or due to the "OR LIKE"...? Q4. Do you recommend rewriting this with mysql's INSTR() / LOCATE() / MATCH..AGAINST [FULLTEXT]?

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  • Formatting inline many-to-many related models presented in django admin

    - by Jonathan
    I've got two django models (simplified): class Product(models.Model): name = models.TextField() price = models.IntegerField() class Invoice(models.Model): company = models.TextField() customer = models.TextField() products = models.ManyToManyField(Product) I would like to see the relevant products as a nice table (of product fields) in an Invoice page in admin and be able to link to the individual respective Product pages. My first thought was using the admin's inline - but django used a select box widget per related Product. This isn't linked to the Product pages, and also as I have thousands of products, and each select box independently downloads all the product names, it quickly becomes unreasonably slow. So I turned to using ModelAdmin.filter_horizontal as suggested here, which used a single instance of a different widget, where you have a list of all Products and another list of related Products and you can add\remove products in the later from the former. This solved the slowness, but it still doesn't show the relevant Product fields, and it ain't linkable. So, what should I do? tweak views? override ModelForms? I Googled around and couldn't find any example of such code...

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  • How to display my server's current response time to an average user

    - by Jason
    Sorry, I'm not really sure of the right way to ask this one so bear with me... We have a web application that runs on a set of servers at a data center (not in our offices) We want to be able to somehow 'advertise' to our clients/users that the availability or response time of our servers has met a standard throughout the day. I am being asked to come up with a standard metric that we can easily advertise on our login screen that shows current "standard response time" checked every x minutes. My thinking is that I need to capture something like the results of a traceroute from a server (either in our office, amazon, etc..) to one of the data center servers and come up with a Red/Yellow/Green type of a notifier for the login screen to let the user know that our tests are responding normally and if they are having delay issues it could be their network or connection to the internet. We have lots of clients in rural areas that have poor connectivity and we are trying to let them know any slowness might be on their end, not ours. I've got the LAMP stack to work with, but this could also be some other system all together as long as it can update the main server with the results. I already have pingdom reports that are available, but that's a bit more than people want to read sometimes. Any ideas on what I can do?

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  • How do I track down sporadic ASP.NET performance problems in a production environment?

    - by Steve Wortham
    I've had sporadic performance problems with my website for awhile now. 90% of the time the site is very fast. But occasionally it is just really, really slow. I mean like 5-10 seconds load time kind of slow. I thought I had narrowed it down to the server I was on so I migrated everything to a new dedicated server from a completely different web hosting company. But the problems continue. I guess what I'm looking for is a good tool that'll help me track down the problem, because it's clearly not the hardware. I'd like to be able to log certain events in my ASP.NET code and have that same logger also track server performance/resources at the time. If I can then look back at the logs then I can see what exactly my website was doing at the time of extreme slowness. Is there a .NET logging system that'll allow me to make calls into it with code while simultaneously tracking performance? What would you recommend?

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  • Optimization in Python - do's, don'ts and rules of thumb.

    - by JV
    Well I was reading this post and then I came across a code which was: jokes=range(1000000) domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)] I thought wouldn't it be better to calculate the value of len(jokes) once outside the list comprehension? Well I tried it and timed three codes jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)]' 10000000 loops, best of 3: 0.0352 usec per loop jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);l=len(jokes);domain=[(0,(l*2)-i-1) for i in range(0,l*2)]' 10000000 loops, best of 3: 0.0343 usec per loop jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);l=len(jokes)*2;domain=[(0,l-i-1) for i in range(0,l)]' 10000000 loops, best of 3: 0.0333 usec per loop Observing the marginal difference 2.55% between the first and the second made me think - is the first list comprehension domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)] optimized internally by python? or is 2.55% a big enough optimization (given that the len(jokes)=1000000)? If this is - What are the other implicit/internal optimizations in Python ? What are the developer's rules of thumb for optimization in Python? Edit1: Since most of the answers are "don't optimize, do it later if its slow" and I got some tips and links from Triptych and Ali A for the do's. I will change the question a bit and request for don'ts. Can we have some experiences from people who faced the 'slowness', what was the problem and how it was corrected? Edit2: For those who haven't here is an interesting read Edit3: Incorrect usage of timeit in question please see dF's answer for correct usage and hence timings for the three codes.

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  • PostgreSQL, Foreign Keys, Insert speed & Django

    - by Miles
    A few days ago, I ran into an unexpected performance problem with a pretty standard Django setup. For an upcoming feature, we have to regenerate a table hourly, containing about 100k rows of data, 9M on the disk, 10M indexes according to pgAdmin. The problem is that inserting them by whatever method literally takes ages, up to 3 minutes of 100% disk busy time. That's not something you want on a production site. It doesn't matter if the inserts were in a transaction, issued via plain insert, multi-row insert, COPY FROM or even INSERT INTO t1 SELECT * FROM t2. After noticing this isn't Django's fault, I followed a trial and error route, and hey, the problem disappeared after dropping all foreign keys! Instead of 3 minutes, the INSERT INTO SELECT FROM took less than a second to execute, which isn't too surprising for a table <= 20M on the disk. What is weird is that PostgreSQL manages to slow down inserts by 180x just by using 3 foreign keys. Oh, disk activity was pure writing, as everything is cached in RAM; only writes go to the disks. It looks like PostgreSQL is working very hard to touch every row in the referred tables, as 3MB/sec * 180s is way more data than the 20MB this new table takes on disk. No WAL for the 180s case, I was testing in psql directly, in Django, add ~50% overhead for WAL logging. Tried @commit_on_success, same slowness, I had even implemented multi row insert and COPY FROM with psycopg2. That's another weird thing, how can 10M worth of inserts generate 10x 16M log segments? Table layout: id serial primary, a bunch of int32, 3 foreign keys to small table, 198 rows, 16k on disk large table, 1.2M rows, 59 data + 89 index MB on disk large table, 2.2M rows, 198 + 210MB So, am I doomed to either drop the foreign keys manually or use the table in a very un-Django way by defining saving bla_id x3 and skip using models.ForeignKey? I'd love to hear about some magical antidote / pg setting to fix this.

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  • Slow Python HTTP server on localhost

    - by Abiel
    I am experiencing some performance problems when creating a very simple Python HTTP server. The key issue is that performance is varying depending on which client I use to access it, where the server and all clients are being run on the local machine. For instance, a GET request issued from a Python script (urllib2.urlopen('http://localhost/').read()) takes just over a second to complete, which seems slow considering that the server is under no load. Running the GET request from Excel using MSXML2.ServerXMLHTTP also feels slow. However, requesting the data Google Chrome or from RCurl, the curl add-in for R, yields an essentially instantaneous response, which is what I would expect. Adding further to my confusion is that I do not experience any performance problems for any client when I am on my computer at work (the performance problems are on my home computer). Both systems run Python 2.6, although the work computer runs Windows XP instead of 7. Below is my very simple server example, which simply returns 'Hello world' for any get request. from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer class MyHandler(BaseHTTPRequestHandler): def do_GET(self): print("Just received a GET request") self.send_response(200) self.send_header("Content-type", "text/html") self.end_headers() self.wfile.write('Hello world') return def log_request(self, code=None, size=None): print('Request') def log_message(self, format, *args): print('Message') if __name__ == "__main__": try: server = HTTPServer(('localhost', 80), MyHandler) print('Started http server') server.serve_forever() except KeyboardInterrupt: print('^C received, shutting down server') server.socket.close() Note that in MyHandler I override the log_request() and log_message() functions. The reason is that I read that a fully-qualified domain name lookup performed by one of these functions might be a reason for a slow server. Unfortunately setting them to just print a static message did not solve my problem. Also, notice that I have put in a print() statement as the first line of the do_GET() routine in MyHandler. The slowness occurs prior to this message being printed, meaning that none of the stuff that comes after it is causing a delay.

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  • Efficient update of SQLite table with many records

    - by blackrim
    I am trying to use sqlite (sqlite3) for a project to store hundreds of thousands of records (would like sqlite so users of the program don't have to run a [my]sql server). I have to update hundreds of thousands of records sometimes to enter left right values (they are hierarchical), but have found the standard update table set left_value = 4, right_value = 5 where id = 12340; to be very slow. I have tried surrounding every thousand or so with begin; .... update... update table set left_value = 4, right_value = 5 where id = 12340; update... .... commit; but again, very slow. Odd, because when I populate it with a few hundred thousand (with inserts), it finishes in seconds. I am currently trying to test the speed in python (the slowness is at the command line and python) before I move it to the C++ implementation, but right now this is way to slow and I need to find a new solution unless I am doing something wrong. Thoughts? (would take open source alternative to SQLite that is portable as well)

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  • Suggestion on Database structure for relational data

    - by miccet
    Hi there. I've been wrestling with this problem for quite a while now and the automatic mails with 'Slow Query' warnings are still popping in. Basically, I have Blogs with a corresponding table as well as a table that keeps track of how many times each Blog has been viewed. This last table has a huge amount of records since this page is relatively high traffic and it logs every hit as an individual row. I have tried with indexes on the fields that are included in the WHERE clause, but it doesn't seem to help. I have also tried to clean the table each week by removing old ( 1.weeks) records. SO, I'm asking you guys, how would you solve this? The query that I know is causing the slowness is generated by Rails and looks like this: SELECT count(*) AS count_all FROM blog_views WHERE (created_at >= '2010-01-01 00:00:01' AND blog_id = 1); The tables have the following structures: CREATE TABLE IF NOT EXISTS 'blogs' ( 'id' int(11) NOT NULL auto_increment, 'name' varchar(255) default NULL, 'perma_name' varchar(255) default NULL, 'author_id' int(11) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, 'blog_picture_id' int(11) default NULL, 'blog_picture2_id' int(11) default NULL, 'page_id' int(11) default NULL, 'blog_picture3_id' int(11) default NULL, 'active' tinyint(1) default '1', PRIMARY KEY ('id'), KEY 'index_blogs_on_author_id' ('author_id') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ; And CREATE TABLE IF NOT EXISTS 'blog_views' ( 'id' int(11) NOT NULL auto_increment, 'blog_id' int(11) default NULL, 'ip' varchar(255) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, PRIMARY KEY ('id'), KEY 'index_blog_views_on_blog_id' ('blog_id'), KEY 'created_at' ('created_at') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

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