IZ67874: JAVA JIT COMPILATION THREAD NOT RELEASING VM CLASS TABLE LOCK CAUSING APPLICATION TO HANG.

APAR status

• Closed as program error.

Error description

• Error Message: The application hangs in a random or intermittent
  manner while under heavy load with frequent GC cycles.
  .
  Stack Trace: N/A
  .
  The javacore shows:
  
  1) That the VM class table lock is owned by the JIT Compilation
  Thread and a number of other threads are waiting to obtain the
  lock.
  
  2LKREGMON          VM class table lock (0x...): Flat locked by
   "JIT Compilation Thread" (0x...), entry count 1
  3LKWAITERQ            Waiting to enter:
  3LKWAITER                "ThreadName" (0x...)
  
  2) The JIT-CompilationQueueMonitor lock is unowned.
  
  2LKREGMON          JIT-CompilationQueueMonitor lock (0x...):
   <unowned>
  3LKNOTIFYQ            Waiting to be notified:
  3LKWAITNOTIFY            "JIT Compilation Thread" (0x...)
  
  KEYWORDS
  Deadlock hang
  

Local fix

• This problem can be avoided by using the -Xjit:disableCHTable
  option. Note however that this option may incur a slight
  performance impact.
  

Problem summary

• When a JIT compilation is abandoned while holding the VM class
  table lock, the JIT will never release the lock resulting in any
  future class load operations to hang waiting to obtain the VM
  class table lock.
  

Problem conclusion

• This defect will be fixed in:
  5.0.0 SR12
  .
  The JIT was modified so that the VM class table lock will be
  released when a compilation is abandoned.
  .
  To obtain the fix:
  Install build 20100126 or later
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IZ66183

• APAR is sysrouted TO one or more of the following:

  PM10711

Fix information

• Fixed component name

  JAVA 5 JIT

• Fixed component ID

  620500124

Applicable component levels

• R500 PSN

     UP