APAR status
Closed as program error.
Error description
Error Message: In workloads with high numbers of paralell threads that use DriectByteBuffers, like in almost any WAS deployment, where a volume of direct memory is required that is larger than the default soft limit (but unknown outside runtime demands) it will end up in a situation whee multiple threads are all hitting the soft limits at the same time. It will cause GC storm . Stack Trace: N/A . N/A
Local fix
N/A
Problem summary
When multiple threads enter Bits.reserveMemoty() at same time, threads pass the initial synchronized block quickly but gc triggered by first thread has not yet finished, so all threads will fail to reserve memory and trigger gc in its own thread. This causes gc storm.
Problem conclusion
This defect will be fixed in: 7.0.0 SR6 . The solution is move check and increase Max memory codes to the end of initial synchronized block, so that only the first thread will trigger gc and the following threads will reserve memory successfully in initial synchronized block.
Temporary fix
N/A
Comments
APAR Information
APAR number
IV50585
Reported component name
JAVA CLASS LIBS
Reported component ID
620700130
Reported release
700
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2013-10-08
Closed date
2013-10-08
Last modified date
2013-10-31
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
JAVA CLASS LIBS
Fixed component ID
620700130
Applicable component levels
R700 PSY
UP
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Document Information
Modified date:
21 February 2022