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Bizarre Performance IssuesRSS

8 replies

Last post Apr 17, 2018 01:35 PM by lextm

  • Bizarre Performance Issues

    Feb 15, 2018 05:37 PM|bigun139|LINK

    So, I have two clustered virtual web servers using NLB to merge to a single IP.  NLB is currently configured to use one server at a time.  This was setup so I could apply updates and reboot without interrupting service.  The servers also use FastCGI-PHP as the page language.

    The server has ran fine for several years, then recently, in the past few days, I have noticed a tremendous slowdown on page requests on all of our sites.  The least used ones seems to be the most affected.  At first I thought it was our Max Instances setting, I then set it to 40 instances (10 / per core x 4 cores), but it didn't seem to help.

    Then I noticed something odd.  So long as NLB was using my backup server, the requests were snappy and near-instant.  The moment I go back to our main server, it slowed way down, sometimes taking up to 10+ minutes to get a reply back.  The logs also were reflecting these poor request times on the main server.

    The problem?  These two servers use a shared configuration, any change made to one, is made to the other.  So they are exactly the same.  This means there's got to be something with the virtual server itself, and I have no idea where to start.

    Any help is greatly appreciated.

    *edit*

    I just did a diff-level comparison of php.ini files on both servers, and they are identical as well.

  • Re: Bizarre Performance Issues

    Feb 16, 2018 05:45 AM|mahamr|LINK

    Hi bigun139,

    First place to start is Failed Request Tracing. This will give you timestamps of requests, failed or successful, so you can see how long each step took. This will help narrow down where the slowdowns are occurring.

    https://docs.microsoft.com/en-us/iis/troubleshoot/using-failed-request-tracing/troubleshoot-with-failed-request-tracing

    For the doc above, the settings you choose may not look the same. For example, if the requests are successful, just long running, you'd probably want to also track HTTP 200 statuses, so the status box could be 200 or 200-999, etc.

  • Re: Bizarre Performance Issues

    Feb 16, 2018 10:11 AM|Yuk Ding|LINK

    Hi bigun139,

    First of all, you need to figure out this issue occur from IIS pipeline or fast-cgi. So you could follow mahamr

    's advice to use the failed request tracing. The FRT log will log the time taken for each process. Then you could figure out what the error come out. In addition, didyou install any windows update or change any configuration? I just notice that the windows server power configuration will effect the performance.

    Best Regards,

    Yuk Ding

    Yuk Ding

    MSDN Community Support
    Please remember to "Mark as Answer" the responses that resolved your issue.
  • Re: Bizarre Performance Issues

    Feb 16, 2018 01:46 PM|bigun139|LINK

    Well, this is embarrassing - I need this thread moved to the IIS version 6 section, I'm running 6.2.  If that isn't possible, I'll mark the thread as solved and re-post.

  • Re: Bizarre Performance Issues

    Feb 16, 2018 10:13 PM|mahamr|LINK

    What OS are you running?

  • Re: Bizarre Performance Issues

    Feb 20, 2018 08:19 AM|Yuk Ding|LINK

    Hibigun139,

    So which request is causing the low performance? IIS doesn't have IIS 6.2 version. Which version of IIS are you using indeed.

    Best Regards,

    Yuk Ding

    Yuk Ding

    MSDN Community Support
    Please remember to "Mark as Answer" the responses that resolved your issue.
  • Re: Bizarre Performance Issues

    Apr 16, 2018 05:58 PM|bigun139|LINK

    Sorry this has taken me a while to reply, I had to wait for operations to move to another building to figure out what the heck is going on without disturbing operations.

    It is IIS version 8, I was right to begin with.  Windows Server 2012.

    Request to move to IIS 8 forum.

    *edit*

    Also the "time-taken" in the logs are horrendous.  Anywhere from 0, then to 11,000 and 135,000.  The site is a dokuwiki, and there is no specific pages that seem to be doing it.  The main doku.php file (with no arguments in the URL), I have records of "time-taken" between 0 and 15, all the way up to 13,000+.

    Mind you, I'm looking at one specific site, we have a few, but it doesn't matter what site it is, they all seem to be running slow.

    edit

    Another finding:  The server giving us grief consumes about 25% of the server's computing power to load one request.  The other server takes about 4%.  Same number of cores, same host, same network.

  • Rovastar Rovastar

    5495 Posts

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    Moderator

    Re: Bizarre Performance Issues

    Apr 17, 2018 12:24 AM|Rovastar|LINK

    Like has stated failed request tracing will gather more info.

    The time taken in the IIS logs includes network time. So a slow connection from the other side of the world will give a longer time that local connections.

    It is possible that you have some network issues.

    Maybe crack open a packet sniffer like Wireshark to see what is happening.

    Troubleshoot IIS in style
    https://www.leansentry.com/
  • Re: Bizarre Performance Issues

    Apr 17, 2018 01:35 PM|lextm|LINK

    bigun139

    The server has ran fine for several years, then recently, in the past few days, I have noticed a tremendous slowdown on page requests on all of our sites. 

    I assume this server still runs a very old PHP build, right? PHP is now on a fast release cycle, and you have to upgrade to 7.1 or 7.2 based on the lifecycle policies,

    http://php.net/supported-versions.php 

    Lex Li
    Want to have a chat on the issues you meet? Find me at https://booktime.xyz/p/lextm
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