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  1. #1
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    Premature Connection Closures - What to do?

    Hi,

    I've been running a number of Load Tests over the last few days and im currently encountering 'Premature Connection Closures'.

    Im using LoadRunner to run the tests (but assume this would happen regardless of which tool i'm using?) and the VUsers are connectiong via HTTP to a Weblogic 6.1 application server running on a Windows 2000 Server.

    Server Spec is as follows:
    Dual Processor PIII 600's
    1 gig RAM
    Intel 100+ PRO Ethernet PCI Card

    From a posting to the LoadRunner group yesterday suggestions are that this is a hardware bound issue, so im currently running a series of tests to try and establish at what point I start getting the connection failures.

    Does anyone know what resource issues would cause the server to close the connections prematurely?

    Is this a Network card issue? Or is it processor bound? Or otherwise?

    Using the task manager I can see that the processors are working fairly hard and are busy around 97% of the time, also I still have approximately 500 meg of free RAM.

    Using 'netstat -a' I can see that when runnning 500 Vusers there are approximately 1500 TCP connections on the :7001 port used by Weblogic.

    Should I expect to be able to run more users against this server or am I simply reaching the hardware limits?

    As always any advice appreciated.

    Regards,
    Colin.
    Hope this helps.

    Regards,
    Colin.

  2. #2
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    Re: Premature Connection Closures - What to do?

    Colin whats the time-frame for these dropped connectios and is it always at the same duration or at the same point in the ramp-up process?

    Are you using HTTP Keep-Alive?

    Mark.

    ------------------

  3. #3
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    Re: Premature Connection Closures - What to do?

    Hi Mark,

    I always seem to get the VUsers running without any problem. It is only once they are all running that I encounter the problem.

    I wasn't and haven't used 'HTTP Keep-Alive' before, so I've just added this service request into my startup routine for the VUsers. As I write this a test is currently running but alas still I'm getting some premature connection closures.

    I've scaled my number of users down to 200 and there are certainly less errors?


    ------------------
    Hope this helps.

    Regards,
    Colin.
    Hope this helps.

    Regards,
    Colin.

  4. #4
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    Re: Premature Connection Closures - What to do?

    Is weblogic configured to use keep-alives? Are you logging in as different unique user? Are you IP spoofing?

    Sometimes Weblogic has trouble identifying and tracking that many unique users coming from the same IP which causes sockets to drop connections.

    Using fewer users will cause fewer errors, but will not solve the problems.

    ------------------
    Scott Barber
    NOBLE(STAR
    Sr. Performance Engineer
    sbarber@noblestar.com
    http://www.noblestar.com
    Scott Barber
    Chief Technologist, PerfTestPlus
    Executive Director, Association for Software Testing
    Co-Author, Performance Testing Guidance for Web Applications
    sbarber@perftestplus.com

    If you can see it in your mind...
    you will find it in your life.

  5. #5
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    Re: Premature Connection Closures - What to do?

    Hi Guys,

    Unfortunately not going to get a chance to check on this now till Tuesday, (off on holiday for a couple of days).

    Keep the suggestions coming!

    Thanks.

    Colin
    Hope this helps.

    Regards,
    Colin.

  6. #6
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    Re: Premature Connection Closures - What to do?

    Hi Scott,

    Checked out your points and to confirm:

    - Weblogic is configured to use keep-alives and has a default 30 sec timeout set
    - Our application as yet doesn't have logins
    - IP Spoofing is OFF

    Colin.

    ------------------
    Hope this helps.

    Regards,
    Colin.
    Hope this helps.

    Regards,
    Colin.

  7. #7
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    Re: Premature Connection Closures - What to do?

    Ok, does your application track sessions at all, possibly using cookies?

    If the application tracks session, and all your users are coming from one IP, it is entirely possible that Rational/Weblogic is getting the users jumbled and closing connections. (over simplified explanation)

    Check the weblogic server logs and see if they give you any more information. If not, see if you can't get IP spoofing set up, or figure out exactly HOW or IF your app identifies users.

    As a side note, check your script, see if there are "server connection invalid" notes in the script. If you got it during the initial recording, you're going to get it during playback, and not necessarily in the same place.

    ------------------
    Scott Barber
    NOBLE(STAR
    Sr. Performance Engineer
    sbarber@noblestar.com
    http://www.noblestar.com
    Scott Barber
    Chief Technologist, PerfTestPlus
    Executive Director, Association for Software Testing
    Co-Author, Performance Testing Guidance for Web Applications
    sbarber@perftestplus.com

    If you can see it in your mind...
    you will find it in your life.

  8. #8
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    Re: Premature Connection Closures - What to do?

    Hi,

    - Weblogic assigns each user/virtual user with a session id which stays with the user for the duration of the test, this is how users are uniquely identified.

    - I appear to encounter the same dropped connections regardless or not as to whether IP spoofing is enabled in LoadRunner.

    - The scripts were all hand crafted as there is currently no user interface (sigh), so I dont have any "server connection invalid" statements that I can find.

    - Im going to go do another run just now and speak with one of our Java developers with regards which weblogic logs to examine, so ill keep you posted!

    Again, thanks for the input.

    Colin
    Hope this helps.

    Regards,
    Colin.

  9. #9
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    Re: Premature Connection Closures - What to do?

    I wish you luck - let me know if you find out anything interesting.

    ------------------
    Scott Barber
    NOBLE(STAR
    Sr. Performance Engineer
    sbarber@noblestar.com
    http://www.noblestar.com
    Scott Barber
    Chief Technologist, PerfTestPlus
    Executive Director, Association for Software Testing
    Co-Author, Performance Testing Guidance for Web Applications
    sbarber@perftestplus.com

    If you can see it in your mind...
    you will find it in your life.

  10. #10
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    Re: Premature Connection Closures - What to do?

    Hi,

    Still no resolution as yet.

    I've posted to the weblogic.developer.interest.performance group on 'groups.google.com' and re-activated a thread in the LoadRunner discussion group on Mercury's support site.

    If/when I find a resoltion or otherwise ill update this thread.

    Thanks for all the suggestions.

    Regards,
    Colin
    Hope this helps.

    Regards,
    Colin.

 

 
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