APAR status
Closed as program error.
Error description
Error Message: N/A . Stack Trace: N/A . Symptoms of the issue are long GC pause times where verbose GC reports reasonable GC time but the overall pause time is unacceptable"
Local fix
The issue can be circumvented by using -Xjit:noRecompile,disableCHOpts,disableCHTable. Note however that in some cases this may reduce peak throughput of the application.
Problem summary
The JIT compiler can generate code that may become invalid in the future (for instance if the class hierarchy changes since the compilation took place). When such code is generated the JIT registers a "runtime assumption" with the runtime system. If the assumption is violated the JIT will take corrective actions (recompiling the method or patching the code). These runtime assumptions need to be cleaned-up when the method they belong to gets recompiled or unloaded. Depending on the number of assumptions being generated, in some cases the cleanup procedure may introduce larger than usual GC pauses.
Problem conclusion
This defect will be fixed in: 7.0.0 SR4 6.0.1 SR5 6.0.0 SR13 . The runtime assumption cleanup algorithm has been changed to reduce its overhead which in turn should reduce GC pauses.
Temporary fix
Comments
APAR Information
APAR number
IV35862
Reported component name
JIT
Reported component ID
620700124
Reported release
260
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2013-01-24
Closed date
2013-04-18
Last modified date
2013-04-18
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
R260 PSY
UP
R600 PSY
UP
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Document Information
Modified date:
18 April 2013