APAR status
Closed as program error.
Error description
Error Message: Different symptoms are possible. These includes crashes/abends/assertion/unexpected exceptions errors in the VM, GC, and JIT compiled code. Detailed analysis is needed to identify this problem. . Stack Trace: N/A . These problems can only occur on IBM Z platforms. The likelihood of hitting an HPR problem seems to have significantly increased around Java 8 SR5 FP20.
Local fix
It's possible to emulate the effect of this change to the JVM by using the following java command line options. -Xjit:disableHighWordRA,disableHPRSpill,disableHPRUpgrade These options will prevent the JIT from using HPR registers and therefore cause the JIT to behave much like the JIT does after the changes were applied to the JVM as part of this APAR. Using these options may have a minor effect on performance (but no more so then what would be seen after upgrading to a JVM that has this APAR included).
Problem summary
The JIT compiler uses halfword general purpose registers (HPRs) as part of its generated code. Recent optimizations have exposed problematic scenarios around the existing HPR exploitation. While this exploitation once provided a performance benefit, newer hardware has negated this difference.
Problem conclusion
The JIT compiler's use of HPRs has been deprecated. . This APAR will be fixed in the following Java Releases: 8 SR5 FP31 (8.0.5.31) . 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
IJ17056
Reported component name
JIT
Reported component ID
620700124
Reported release
130
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-06-19
Closed date
2020-02-14
Last modified date
2020-02-14
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
[{"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:
27 March 2020