Topic
  • 7 replies
  • Latest Post - ‏2013-02-13T09:42:13Z by SystemAdmin
SystemAdmin
SystemAdmin
37422 Posts

Pinned topic waiting and blocked threads in javacore

‏2013-02-12T17:24:18Z |
Hi,

I can see a large number of threads waiting and blocked in javacore and for each thread I can see following stack trace

at java/lang/Object.wait(Native Method)
at java/lang/Object.wait(Object.java:196(Compiled Code))
at com/ibm/ws/util/BoundedBuffer.waitGet_(BoundedBuffer.java:179(Compiled Code))
at com/ibm/ws/util/BoundedBuffer.take(BoundedBuffer.java:523(Compiled Code))
at com/ibm/ws/util/ThreadPool.getTask(ThreadPool.java:872(Compiled Code))
at com/ibm/ws/util/ThreadPool$Worker.run(ThreadPool.java:1611(Compile code))

Does any one have any idea about these stack trace? I am using Thread and Monitor Dump Analyzer for Java.

Please advise!
Thanks,

Kashif
Updated on 2013-02-13T09:42:13Z at 2013-02-13T09:42:13Z by SystemAdmin
  • bpaskin
    bpaskin
    4212 Posts

    Re: waiting and blocked threads in javacore

    ‏2013-02-12T17:33:15Z  
    Waiting for work for the web containers. These are normal and you can change the number in the web container thread pool.

    Brian
  • SystemAdmin
    SystemAdmin
    37422 Posts

    Re: waiting and blocked threads in javacore

    ‏2013-02-12T17:40:19Z  
    • bpaskin
    • ‏2013-02-12T17:33:15Z
    Waiting for work for the web containers. These are normal and you can change the number in the web container thread pool.

    Brian
    Thank you Brian for the quick reply! Waiting threads are fine but how about blocked threads? I have improved the response time of the site by increasing webcontainer thread pool, JDBC connection pool and PreParedstament cache as I was able to see saturation in these areas but the response time still needs to be reduced.

    you have mentioned to change the webcontainer thread pool, do you want me to increase it more?

    Regards,

    Kashif
  • bpaskin
    bpaskin
    4212 Posts

    Re: waiting and blocked threads in javacore

    ‏2013-02-12T18:06:04Z  
    Thank you Brian for the quick reply! Waiting threads are fine but how about blocked threads? I have improved the response time of the site by increasing webcontainer thread pool, JDBC connection pool and PreParedstament cache as I was able to see saturation in these areas but the response time still needs to be reduced.

    you have mentioned to change the webcontainer thread pool, do you want me to increase it more?

    Regards,

    Kashif
    Hi,

    You posted a stack trace, not blocked threads, so it is hard for me to understand what is going on. If increasing web container threads has helped you, I would check their usage and the time they take to complete when running your tests.

    Brian
  • Sunit
    Sunit
    199 Posts

    Re: waiting and blocked threads in javacore

    ‏2013-02-12T18:28:15Z  
    Thank you Brian for the quick reply! Waiting threads are fine but how about blocked threads? I have improved the response time of the site by increasing webcontainer thread pool, JDBC connection pool and PreParedstament cache as I was able to see saturation in these areas but the response time still needs to be reduced.

    you have mentioned to change the webcontainer thread pool, do you want me to increase it more?

    Regards,

    Kashif
    Use IBM WAIT tool to analyze:
    https://wait.ibm.com/

    --Sunit
  • SystemAdmin
    SystemAdmin
    37422 Posts

    Re: waiting and blocked threads in javacore

    ‏2013-02-12T19:12:01Z  
    • bpaskin
    • ‏2013-02-12T18:06:04Z
    Hi,

    You posted a stack trace, not blocked threads, so it is hard for me to understand what is going on. If increasing web container threads has helped you, I would check their usage and the time they take to complete when running your tests.

    Brian
    HI Brian,

    I have also attached javacore file in my first post, If you get a chance please take a look; you will see blocked threads.

    Thanks,

    Kashif
  • bpaskin
    bpaskin
    4212 Posts

    Re: waiting and blocked threads in javacore

    ‏2013-02-12T20:13:08Z  
    HI Brian,

    I have also attached javacore file in my first post, If you get a chance please take a look; you will see blocked threads.

    Thanks,

    Kashif
    To really look if there are problems you need 3 javacores that are spaced 2 mins or so apart.

    Brian
  • SystemAdmin
    SystemAdmin
    37422 Posts

    Re: waiting and blocked threads in javacore

    ‏2013-02-13T09:42:13Z  
    • bpaskin
    • ‏2013-02-12T20:13:08Z
    To really look if there are problems you need 3 javacores that are spaced 2 mins or so apart.

    Brian
    Ok then I will have to execute load test again and generate 3 javacores. Would you like to suggest any other tool to analyze javacores? If I see more than 50% thread in block condition at the peak of load does it indicates that there is some blockage?
    Kashif