APAR status
Closed as program error.
Error description
Error Message: SIGSEGV after replacing classes using a java agent. . Stack Trace: {libj9jit23.so}{ppcCreateMethodTrampoline()} {libj9jit23.so}{createTrampoline()} {libj9jit23.so}{syncTempTrampolines()} {libj9jit23.so}{synchronizeTrampolines()} {libj9jit23.so}{jitHookGlobalGCEnd()} ... . This problem can only occur on PPC platforms (AIX and LinuxPPC). The problem has only even been seen on Java5. The way Java6 (and up) handles Java agents has changed making the problem nearly impossible to hit in Java6 and up. In order to hit this problem there must be no fewer then 2 class replace events and the JIT must consume more then one code cache (8mb by default). A class replace events are normally caused by requesting a Java agent to begin profiling a set of methods.
Local fix
There is no way to avoid this problem other then to avoid causing the java agent to replace classes or discontinue to use of the java agent completely.
Problem summary
When a class is replaced the Java5 JIT will discontinue using all previously compiled method bodies and revert to the interpreter until methods are compiled again. If this event occurs twice, there maybe pending long jump trampoline patch requests that will fail as the compiled code is no longer registered with the JVM.
Problem conclusion
This defect will be fixed in: 5.0.0 SR14 . The JIT was modified to handle this case appropriately.
Temporary fix
Comments
APAR Information
APAR number
IV16593
Reported component name
JAVA 5 JIT
Reported component ID
620500124
Reported release
500
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2012-03-08
Closed date
2012-05-18
Last modified date
2012-05-18
APAR is sysrouted FROM one or more of the following:
IV16590
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
JAVA 5 JIT
Fixed component ID
620500124
Applicable component levels
R500 PSY
UP
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Document Information
Modified date:
18 May 2012