APAR status
Closed as program error.
Error description
Error Message: The problem can manifest as a crash running J9VMInternals.fastIdentityHashCode with a dereference of an invalid memory address. This may manifest as a NullPointerException from J9VMInternals.fastIdentityHashCode or Object.hashCode. Note this issue only occurs when running a 64-bit JVM with compressed references. 32-bit JVMs and 64-bit JVMs running without compressed references are not affected. . Stack Trace: N/A .
Local fix
The problem can be worked around with -Xjit:dontInline={java/lang/J9VMInternals.fastIdentityHashCode*} ,exclude={java/lang/J9VMInternals.fastIdentityhashCode*}. Note that this can have a significant negative impact on throughput peformance. Another alternative is -Xnocompressedreferences, but this may require a large maximum heap size (-Xmx).
Problem summary
J9VMInternals.fastIdentityHashCode(Object) incorrectly sign-extended the 32bit J9Class pointer when reading it from an object header in a compressedrefs VM. This can can cause crashes with i.e. InaccessibleReadAddress=FFFFFFFF999609D8
Problem conclusion
The code has been modified to do an unsigned widening rather than a signed widening to ensure we generate the correct memory address. . This APAR will be fixed in the following Java Releases: 8 SR5 FP11 (8.0.5.11) . 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
IJ10920
Reported component name
JIT
Reported component ID
620700124
Reported release
130
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2018-10-31
Closed date
2018-10-31
Last modified date
2018-10-31
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
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:
31 October 2018