Enable trace points to check for situations in which no
dump is produced after a crash.
About this task
Check for the situations in which no dump is produced after
a crash by enabling trace points near the shut down of the Java™ runtime environment. If the trace points
overlap with the crash condition, you have confirmation that the race
condition occurred. The tracepoints in the protectedDestroyJavaVM are
the last to be triggered before the main thread returns.
Procedure
- Find the protectedDestroyJavaVM function
tracepoints in the J9TraceFormat.dat file by
using the instructions in Determining the tracepoint ID of a tracepoint.
- When you have the tracepoint IDs, rerun the failing scenario
with those tracepoints sent to the console.
The results are similar to the following
output:
java -Xtrace:print=tpnid{j9vm.381-394} MyApp
11:10:09.421*0x42cc1a00 j9vm.385 > protectedDestroyJavaVM
11:10:09.421 0x42cc1a00 j9vm.386 - protectedDestroyJavaVM waiting for Java threads to
stop
11:10:09.421 0x42cc1a00 j9vm.387 - protectedDestoryJavaVM all Java threads have stopped
11:10:09.421 0x42cc1a00 j9vm.388 - protectedDestroyJavaVM protectedDestroyJavaVM
vmCleanup complete
11:10:09.421 0x42cc1a00 j9vm.389 - protectedDestroyJavaVM VM Shutting Down Hook Fired
Unhandled exception
Type=Segmentation error vmState=0x00000000
J9Generic_Signal_Number=00000004 ExceptionCode=c0000005 ExceptionAddress=430514BE ContextFlags=0001003f
Handler1=7FEE9C40 Handler2=7FEC98C0 InaccessibleAddress=00000000
EDI=000A70A0 ESI=432235D8 EAX=00000000 EBX=00192684
ECX=00000001 EDX=4368FECC
EIP=430514BE ESP=4368FED4 EBP=4368FED8 EFLAGS=00010246
Module=failing_module.dll
Module_base_address=43050000 Offset_in_DLL=000014be
11:10:09.421 0x42cc1a00 j9vm.390 - Target=2_40_20081203_026494_lHdSMr (Windows XP 5.1
build 2600 Service Pack 2)
protectedDestroyJavaVM GC HeapManagement ShutdownCPU=x86 (2 logical CPUs) (0x7fe6b000 RAM)
11:10:09.421 0x42cc1a00 j9vm.391 - protectedDestroyJavaVM vmShutdown returned
11:10:09.421 0x42cc1a00 j9vm.393 - protectedDestroyJavaVM terminateRemainingThreads failed
The
Unhandled exception
message is printed after the first tracepoints for the
protectedDestroyJavaVM function. This output shows that the crash occurred very
late in the life of the Java runtime environment, and that
enough time remained to produce the dump files before the process ended.
What to do next
When you confirm that a race condition has occurred, you might still be able to obtain a
system dump file. For more information, see Obtaining system dump files in a race condition.