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Thread: High load when idle

  1. #1
    Join Date
    Mar 2012
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    12

    Default High load when idle

    Hello,

    I'm currently having a fairly high load(sometimes up to 0.50) while my servers are completely idle. When I stop Wowza, the load drops back to 0.00.

    This issue seems to be appearing only when using the new Ubuntu Server 12.04 LTS (64 bit). When I run Wowza on my desktop, the load stays around 0.00. I've followed the performance tuning guide, but without success, the issue also appears on a completely default installation.

    The servers have new Intel quad cores with hyperthreading and 24GB RAM. The cpu is 99-100% idle at all times, memory usage is practically nothing, disk isn't used at all and the network isn't used except for some ssh traffic. The issue also appears on our testing virtual machines which have 1 core and 1GB each, the loads sometimes goes up to 2 on those machines, also while completely idle.

    Am I overlooking something?

    An strace of several(but not all) java threads results in spamming the following messages:
    FUTEX_WAKE_PRIVATE, 1 = 0
    FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1 = -1 ETIMEDOUT (Connection timed out)

    Although I have no idea if this could be the problem.

  2. #2
    Join Date
    Dec 2007
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    22,013

    Default

    Are you talking about CPU or memory use? If memory, this is expected. The java heap size is the amount of memory that Java reserves. It will appear to be in use. Monitor with JMX/JConsole to see how much is actually being used

    Richard

  3. #3
    Join Date
    Mar 2012
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    12

    Default

    I'm not talking about either of them, at least I think. As I said the memory usage is almost nothing and the cpu is 99%-100% idle all the time. I can't explain why the load gets this high, but for me it only appears to be an issue when having Wowza running and doesn't happen on older Ubuntu versions. I think it's some issue between the new Ubuntu 12.04 and Wowza, but I can't find the issue.

    No idea how Wowza is being tested internally, has it been tested on Ubuntu 12.04 and did you experience the same issues?

  4. #4
    Join Date
    Dec 2007
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    Default

    What load are you referring to other than CPU or memory?

    Richard

  5. #5
    Join Date
    Mar 2012
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    12

    Default

    I'm referring to unix load. Wowza is demanding a lot of CPU time, even though the actualy CPU% usage is close to nothing.

  6. #6
    Join Date
    Dec 2007
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    Default

    If actual CPU and memory usage is low you are okay, good to stream. We do have a load test tool. You have to write to test@wowza.com to request it. There is a document to sign and return.

    Richard

  7. #7
    Join Date
    Mar 2012
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    12

    Default

    It's not a problem now, when idle, but it definitely will be a problem later. I did some extra testing and the problem does not appear on Ubuntu Server 11.04. I have tried different versions of Java in Ubuntu 12.04, including the latest version from the Oracle website, all without success.

    I manually updated the kernel to a 3.3 release and the problem is gone. I have no idea whether the kernel can't play nice with Java/Wowza, or there simply is some sort of bug in the 3.2 kernel branch.

    - Edit
    An update to the 3.2.16 kernel also solves the problem.

    https://bugs.launchpad.net/ubuntu/+s...ux/+bug/995284
    http://www.smythies.com/~doug/networ...age/index.html
    Last edited by Sander; 05-14-2012 at 06:51 AM.

  8. #8
    Join Date
    Dec 2007
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    Default

    Okay, thanks for the update.

    Richard

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