IJ25403: JIT CRASH DURING CLASS UNLOADING IN J9METHOD_HT::ONCLASSUNLOADING()

APAR status

• Closed as program error.

Error description

• Error Message: A SIGSEG is received during class unloading.
  .
  Stack Trace:
  {libj9jit29.so}{J9Method_HT::onClassUnloading(J9ClassLoader*)}
   {libj9jit29.so}{jitHookClassLoaderUnload(J9HookInterface**,...)
  }
   {libj9hookable29.so}{J9HookDispatch(J9HookInterface**,...)}
   {libj9vm29.so}{cleanUpClassLoader}
   {libj9gc29.so}{MM_ClassLoaderManager::cleanUpClassLoaders(...)}
  .
  The problem can occur on any platform running the J9 JVM
  starting with Java 8.0.5.0. Releases prior to that do not have
  this problem.
  

Local fix

• The problem can be avoided by disabling the Dynamic Loop
  Transfer optimization in the JIT. This will have a small effect
  on startup performance as it might take longer for some methods
  to start running in compiled code form.
  -Xjit:disableDynamicLoopTransfer
  

Problem summary

• The JIT would fail to remove some data referencing methods of
  classes that are being unloaded. This results in future unload
  attempts to fail when attempting to access memory from methods
  that have already been unloaded previously resulting in a SEGV
  if that memory has been allocated for other purposes.
  

Problem conclusion

• The JIT has been modified so that references to classes being
  unloaded is properly removed.
  .
  This APAR will be fixed in the following Java Releases:
     8    SR6 FP15  (8.0.6.15)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
             https://www.ibm.com/developerworks/java/jdk/
  

Temporary fix

Comments

APAR Information

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

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

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels