1 Reply Latest reply: Dec 1, 2008 10:34 AM by 843829 RSS

    ConcMarkSweepGC Deadlock?

    843829
      Hello, I was wondering if anyone has experienced a deadlock with the ConcMarkSweepGC option? I am running a pretty simple single threaded application that reads some data from a file, does some processing, then inserts this into a database.

      The process uses a lot of ram and we're getting lots of full collections, so I thought i'd try to speed things up with this option (My logic was that we have the extra CPUs, we might as well help them reduce the time waiting for a full collection. Let me know if this is not a valid strategy).

      Right about when a minor(?) collection should happen, the program just hung. What once was a pretty busy CPU is now idle too. Now, this is a pretty well tested program that has been run quite a bit without ever experiencing this behavior. The jvm options I used were:

      -XX:+UseConcMarkSweepGC
      -verbose:gc
      -Xmx5000m -Xms4000m

      The last few things printed out by the GC were:

      [ParNew 3653866K->3640583K(4695928K), 0.0303440 secs]


      [ParNew 3661703K->3648492K(4695928K), 0.0297930 secs]


      [ParNew 3669612K->3656325K(4695928K), 0.0282990 secs]
      ~~~hangs here~~~

      The box is running version 1.5.0_15. Its a dual Intel Xeon 3.0 each with two cores. If this is a problem with the GC implementation, I hope this helps and would be happy to answer any more questions. If its a problem with my program, I'm happy to also take constructive criticism. :-)

      --Vince                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
        • 1. Re: ConcMarkSweepGC Deadlock?
          843829
          I have experienced this using a number of different java versions 1.4 1.5 & 1.6

          I have repeatedly logged this issue with sun but unfortunetly this is ignored without any further investigation or feedback.

          This is a real issue with Production Servers and sun is ignoring the issue.