APAR status
Closed as program error.
Error description
Error Message: An Intermittent ClassCastException is thrown. Other symptoms are also possible depending on how the java code was written to respond to the return value when calling Class.instanceOf(). . Stack Trace: N/A . This issue can only occur on the POWER version of the J9 JVM (AIX and LinuxPCC, LinuxPPCle). All other architectures are not effected by this issue. The issue was first introduced in Java 8.0.6.36, earlier version of the J9 JVM are not subject to this issue. The issue only effects methods that contain a call to Class.instanceOf(), the instanceof keyword is not effected. In addition, the type of the class must not be statically knowable in order for the problem to occur.
Local fix
The issue can be avoided by using the following java command line argument: -Xjit:disableInlineIsInstance This will have a minor effect on performance when handling some types of cases where the JIT needs to do an instanceof check (but it's not limited to just Class.instanceOf() calls). You can reduce the performance cost by limiting this option so it only effects the method that is known to trigger this issue: -Xjit:{pkg/class.method*}(disableInlineIsInstance) Where "pkg/class.method" is replaced with the full name of the effected method.
Problem summary
When the JIT compiles a method with a call to Class.isInstance() the code might return an incorrect result. Specifically, it may return True when it should be False.
Problem conclusion
The JIT was modified to prevent it from incorrectly returning True. . This APAR will be fixed in the following Releases: . IBM SDK, Java Technology Edition 8 SR6 FP20 (8.0.6.20) . Contact your IBM Product's Service Team for these Service Refreshes and Fix Packs. For those running stand-alone, information about the available maintenance can be found at: https://www.ibm.com/support/pages/java-sdk
Temporary fix
Comments
APAR Information
APAR number
IJ42263
Reported component name
JIT
Reported component ID
620700124
Reported release
130
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2022-09-01
Closed date
2022-09-14
Last modified date
2022-09-14
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":"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:
14 September 2022