APAR status
Closed as program error.
Error description
Error Message: "java.lang.ClassCastException" . Stack Trace: . "This issue can only occur on IBM Z (zOS/Linux on Z and LinuxONE) and cannot occur on POWER or x86 systems."
Local fix
"Using JIT option -Xjit:maxOnsiteCacheSlotForInstanceOf=0 will disable the part of the code that causes the issue. If running with Shared Class Cache with AOT enabled, you need to first clear the shared class cache (See https://www.ibm.com/support/knowledgecenter/SSYKE2_8.0.0/openj9/ xshareclasses/index.html#destroy-cache-utility ) and in subsequent runs you need to disable the optimization from both JIT compiled code and AOT compiled code using java options -Xjit:maxOnsiteCacheSlotForInstanceOf=0 -Xaot:maxOnsiteCacheSlotForInstanceOf=0. Depending on the application, this workaround will have less than 1% performance impact on the application"
Problem summary
On IBM Z, the JIT was reading/updating the instanceOf cache using two instructions which would allow for a race condition resulting in the possibility of a ClassCastException being thrown when two threads concurrently access the instanceOf cache.
Problem conclusion
Compiler code has been updated to generate appropriate code to load and store such associated information in single operation. . This APAR will be fixed in the following Java Releases: 8 SR6 FP15 (8.0.6.15) . 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
N/A
Comments
APAR Information
APAR number
IJ26324
Reported component name
JIT
Reported component ID
620700124
Reported release
130
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2020-07-16
Closed date
2020-07-16
Last modified date
2020-07-16
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":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSNVBF","label":"Runtimes for Java Technology"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"130","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]
Document Information
Modified date:
17 July 2020