APAR status
Closed as program error.
Error description
Error Message: Hang with the javacore file showing a deadlock. Many cases show a deadlock between a StringBuffer and a SystemOutputStream object, but other object types are possible. . Stack Trace: N/A . The problem is most likely to occur in Java 7.1 and Java 8.0. It's is very unlikely to occur on Java 7.0 / 6.1 and it is only possible when using the -Xaggressive option on 7.0 / 6.1. The problem is not possible in Java 6.0. Typically, one of the objects involved in the deadlock will have a very high "entry count" as seen in the javacore.
Local fix
The problem can be avoided by using the java command line option "-Xjit:disableMonitorCoarsening". If this option does not avoid the problem then this APAR is NOT the cause of the deadlock. The use of this option will have a very minor effect on the performance.
Problem summary
The JIT may try to replace two adjacent monitor entry/exit sequences with one sequence that encapsulates the code locked by both sequences. In rare cases it would do this when one of the entry/exist sequences is inside a loop where the other sequence is not. This would result in the monitor entry being executed more then once inside the loop but only execute the monitor exist once, leaving the object locked incorrectly.
Problem conclusion
The JIT was modified so that monitors will not be combined with they exist at different loop nesting levels. . This APAR will be fixed in the following Java Releases: 7 R1 SR4 (7.1.4.0) 6 R1 SR8 FP40 (6.1.8.40) 7 SR10 (7.0.10.0) 8 SR4 (8.0.4.0) . 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 number
IV91507
Reported component name
JIT
Reported component ID
620700124
Reported release
130
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2016-12-13
Closed date
2016-12-14
Last modified date
2016-12-14
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
R130 PSY
UP
R260 PSY
UP
[{"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSC9HBA","label":"Just In Time (JIT) Compiler"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"130","Edition":"","Line of Business":{"code":"","label":""}}]
Document Information
Modified date:
14 December 2016