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Thread: Tuning for many inputs, few outputs

  1. #1

    Default Tuning for many inputs, few outputs

    Hello awesome forum,

    We have a tuning solution that has been working well, this question is more to see if there is any additional performance we can get out of our system(s). As it stands we have around 100 incoming streams per box and at times this can really cause Java to consume a bunch of resources. Is there a practice to determine how many incoming streams a system can handle? While we do record, no more than 40 of them record at a time, generally closer to 20.

    Here is the Garbage Collection we're using on a 16 core system with 24GB of RAM:
    -Xmx18000M -Xms18000M -XX:+UseConcMarkSweepGC -XX:NewRatio=1 -Xss256k -XX:+AlwaysPreTouch -XX:+CMSScavengeBeforeRemark -XX:ParallelCMSThreads=16 -XX:ParallelGCThreads=16 -XX:MaxTenuringThreshold=0 -XX:SurvivorRatio=4096

    Some of our systems use 10Gbps cards to allow better throughput without having to team the NICs. Most systems just have multiple Gigabit NIC cards. Most of our servers run Debian Wheezy, any known issues with the transcoders on Debian?

    Like I said, no real issues with the system, we do see small hits when the collector runs, but nothing severe. Just looking to improve on the system if we can.

    Thanks,

    Benjamin

  2. #2
    Join Date
    Sep 2011
    Posts
    1,920

    Default

    Hi
    As it's working very well for the most part I assume you've tuned the server to all the max values shown in the tuning guide already,
    http://www.wowza.com/forums/content....ormance-tuning

    How many streams are being concurrently transcoded?
    Are the inbound streams high bitrate HD?

    Jason

  3. #3

    Default

    The transcoding servers are different. These boxes are doing 8Mbps HD streams, so if that is considered high-bitrate then yes.

    We did tune to max values based on what the tuning guide said. The only real item that is sorta left open is the GC. I was looking at using the G1 collector but have not pulled the trigger on that. Any advantage to G1 over what we have now?

    Thanks,

    B

  4. #4

    Default

    Do you adjust the GC settings for OpenJDK?

  5. #5
    Join Date
    Sep 2011
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    1,920

    Default

    Hi
    @ Bencredible,
    The tuning guide says
    If you have 16 GB or more RAM, we suggest a heap size of 8000 MB. We do not suggest a heap size above 10 GB as it can lead to long GC cycles/pauses.
    For the G1 collector it's personal preference when it comes down to GC settings based on what you're happy with.
    I'd change the configuration based on the quote I gave you from the tuning guide and see if that makes a difference with the settings you currently have.

    @ Mikhailov,
    OpenJDK or OracleJDK it makes no difference.
    As they are both free I would recommend for a new install OracleJDK but if the server is already running there is no need to change it.

    Jason

  6. #6

    Default

    If it's no difference, why some applications cause the following warning:

    WARNING: You are launching the IDE using OpenJDK Java runtime.

    ITS KNOWN TO HAVE PERFORMANCE AND GRAPHICS ISSUES!
    SWITCH TO THE ORACLE(SUN) JDK BEFORE REPORTING PROBLEMS!

    Quote Originally Posted by JasonH View Post
    Hi
    @ Bencredible,
    The tuning guide says


    For the G1 collector it's personal preference when it comes down to GC settings based on what you're happy with.
    I'd change the configuration based on the quote I gave you from the tuning guide and see if that makes a difference with the settings you currently have.

    @ Mikhailov,
    OpenJDK or OracleJDK it makes no difference.
    As they are both free I would recommend for a new install OracleJDK but if the server is already running there is no need to change it.

    Jason

  7. #7
    Join Date
    Sep 2011
    Posts
    1,920

    Default

    Quote Originally Posted by mikhailov View Post
    If it's no difference, why some applications cause the following warning:

    WARNING: You are launching the IDE using OpenJDK Java runtime.

    ITS KNOWN TO HAVE PERFORMANCE AND GRAPHICS ISSUES!
    SWITCH TO THE ORACLE(SUN) JDK BEFORE REPORTING PROBLEMS!
    Hi
    I wasn't aware of this warning before now.
    If Wowza has a log message that recommends using OracleJDK due to performance issues in OpenJDK, you need to change to Oracle Java.

    You wouldn't be getting these warning if it wasn't effecting your application(s) in some way.

    Jason

  8. #8
    Join Date
    Dec 2007
    Posts
    22,013

    Default

    I think it is a message from Eclipse. I would ignore it.

    Richard

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