IJ57597: FORCED JVM TERMINATION MAY CAUSE ORPHANED MMAP SEGMENTS ON Z/OS DUE TO JIMAGE LOADING

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: The Java stack trace of the problematic mmap()
  allocation is:
  jdk/internal/jimage/BasicImageReader.<init>(java.nio.file.Path,j
  ava.nio.ByteOrder)
  java.nio.MappedByteBuffer
  sun/nio/ch/FileChannelImpl.map(java.nio.channels.FileChannel$Map
  Mode, long, long)
  sun.nio.ch.FileChannelImpl$Unmapper
  sun/nio/ch/FileChannelImpl.mapInternal(java.nio.channels.FileCha
  nnel$MapMode, long, long, int, boolean)
  sun/nio/ch/FileChannelImpl.map0(int, long, long, boolean)
  .
  Applications running within a Java-enabled IMS region on z/OS
  may experience an out of memory condition due to orphaned
  subpool type 129 segments left by terminated JVMs within the
  same address space.
  

Local fix

• This issue can be mitigated by setting the system property
  -Djdk.image.map.all=false. Note that this workaround may result
  in a minor, typically negligible, performance impact.
  

Problem summary

• In certain circumstances, the Java class BasicImageReader may
  memory-map the 'lib/modules' jimage file (<TLD>170MB). On z/OS,
  mmap() allocates below-the-bar storage of subpool type 129 that
  persists at JOBSTEP level and may not be freed when the JVM
  terminates abnormally, resulting in a possible memory leak.
  

Problem conclusion

• The Java class library has been updated to avoid memory mapping
  the 'lib/modules' file.
  .
  This APAR will be fixed in the following Releases:
  .
  IBM Semeru Runtimes
   21 21.0.11.0
   17 17.0.19.0
   11 11.0.31.0
  .
  Downloads and supplementary documentation can be found at the
  following locations:
  - For non z/OS operating systems:
   - IBM Semeru Runtimes, Version 11 and later
   https://www.ibm.com/semeru-runtimes/downloads/
   - IBM SDK, Java Technology Edition, Version 8
   https://www.ibm.com/support/pages/java-sdk-downloads/
  - For the z/OS operating system:
   - Java SDK Products on z/OS
   https://www.ibm.com/support/pages/java-sdk-products-zos
  

Temporary fix

Comments

APAR Information

• 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

  OPENJDK CLASS L

• Fixed component ID

  621800100

Applicable component levels