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  1. JDK
  2. JDK-6289795

"fair" lock policy in ReentrantLock may cause busy hang

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: P4
    • Resolution: Duplicate
    • Affects Version/s: 5.0
    • Fix Version/s: None
    • Component/s: core-libs
    • Labels:

      Description

      FULL PRODUCT VERSION :
      java version "1.5.0"
      Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64)
      Java HotSpot(TM) Client VM (build 1.5.0-b64, mixed mode, sharing)


      ADDITIONAL OS VERSION INFORMATION :
      SunOS telehouse2 5.9 Generic_112233-11 sun4u sparc SUNW,UltraSPARC-IIi-cEngine

      Linux mirror-us-ga1.gallery.hd.org 2.4.21-27.0.2.EL #1 Wed Jan 19 02:20:34 GMT 2005 i686 i686 i386 GNU/Linux


      EXTRA RELEVANT SYSTEM CONFIGURATION :
      Highly concurrent JSP/J2EE Web app (http://gallery.hd.org/)

      A DESCRIPTION OF THE PROBLEM :
      Simply switching to a "fair" locking policy seems to cause the app to hang consuming 100% CPU.

      See value of USE_FAIR_LOCKS in:

      http://gallery.hd.org/_javadoc/org/hd/d/pg2k/webSvr/exhibit/ExhibitDataHTTPTunnelSource.html

      and:

      http://gallery.hd.org/_javadoc/src-html/org/hd/d/pg2k/webSvr/exhibit/ExhibitDataHTTPTunnelSource.html#line.87

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Simply changing this policy flag seems to cause a hang if true, not if false, rather than just a subtle performance change. It could of course be something subtle in my code, but there should not even be much contention for these locks most of the time.


      ERROR MESSAGES/STACK TRACES THAT OCCUR :
      Here is a relevant hung thread...

      "DataSourceBean: poll() thread" daemon prio=10 tid=0x01b5c028 nid=0x83 runnable
      [0xcee7f000..0xcee7f9c8]
              at java.util.concurrent.locks.AbstractQueuedSynchronizer.fullGetFirstQue
      uedThread(AbstractQueuedSynchronizer.java:1280)
              at java.util.concurrent.locks.AbstractQueuedSynchronizer.getFirstQueuedT
      hread(AbstractQueuedSynchronizer.java:1233)
              at java.util.concurrent.locks.ReentrantLock$FairSync.tryAcquire(Reentran
      tLock.java:208)
              at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireNanos
      (AbstractQueuedSynchronizer.java:1087)
              at java.util.concurrent.locks.ReentrantLock.tryLock(ReentrantLock.java:4
      16)
              at org.hd.d.pg2k.webSvr.exhibit.ExhibitDataHTTPTunnelSource.doRPCRaw(Unk
      nown Source)
              at org.hd.d.pg2k.svrCore.datasource.ExhibitDataTunnelSource.doRPCUnguard
      ed(Unknown Source)
              at org.hd.d.pg2k.svrCore.datasource.ExhibitDataTunnelSource.getGenProps(
      Unknown Source)
              at org.hd.d.pg2k.svrCore.datasource.ExhibitDataSimpleCache._getGenProps(
      Unknown Source)
              at org.hd.d.pg2k.svrCore.datasource.ExhibitDataSimpleCache.poll(Unknown
      Source)
              at org.hd.d.pg2k.webSvr.exhibit.DataSourceBean.poll(Unknown Source)
              at org.hd.d.pg2k.webSvr.exhibit.DataSourceBean$1.run(Unknown Source)



      REPRODUCIBILITY :
      This bug can be reproduced always.

      CUSTOMER SUBMITTED WORKAROUND :
      Avoiding "fair" policy for now.
      ###@###.### 2005-06-23 09:01:17 GMT

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              Assignee:
              martin Martin Buchholz
              Reporter:
              jssunw Jitender S (Inactive)
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