JDK-8253134 : JMM_VERSION should remain at 0x20020000 (JDK 10) in JDK 11
  • Type: Bug
  • Component: core-svc
  • Sub-Component: java.lang.management
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2020-09-14
  • Updated: 2021-07-13
  • Resolved: 2020-09-16
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JDK 11
11.0.10Fixed
Related Reports
CSR :  
JDK-8253136 - JMM_VERSION should remain at 0x20020000 (JDK 10) in JDK 11
Relates :  
JDK-8251498 - JMX: Add a version of ThreadMXBean.dumpAllThreads with a maxDepth argument
Relates :  
JDK-8231209 - [REDO] JDK-8207266 ThreadMXBean::getThreadAllocatedBytes() can be quicker for self thread
Description
JDK-8231209, which was originally pushed to JDK 14, has been backported to 11.0.9 and 11,0.10-oracle. Those backports changed JMM_VERSION from 0x20020000 (JDK 10) to 0x20030000 (JDK 14), which introduced an incompatibility that was overlooked in the backport CSRs JDK-8247807 (11.0.9) and JDK-8248871 (11.0.10-oracle). JDK 11 users checking for JMM_VERSION == 0x20020000 will find 0x2003000 instead and possibly abort. The issue was first noticed as part of reviewing a backport of JDK-8185003 to JDK 8: see the Description in the corresponding CSR JDK-8251498.

For the reasons detailed there, JMM_VERSION in JDK 11 should be reverted to 0x20020000 (JDK 10), and the @since javadoc tag for com.sun.management.ThreadMXBean.getCurrentThreadAllocatedBytes should be changed from 14 to 11.0.9.
Comments
URL: https://hg.openjdk.java.net/jdk-updates/jdk11u/rev/f25afbb709e0 User: phh Date: 2020-09-16 15:47:22 +0000
16-09-2020
This fix actually undoes a part of the JDK-8231209 backport and restores JMM_VERSION to its initial value. I think this should go into 11.0.9 to avoid any incompatibilities as described in the bug description. The trivial change has been reviewed and the associated CSR ( JDK-8253136) has been approved already. Webrev: http://cr.openjdk.java.net/~phh/8253134/webrev.11u.00/ Review: https://mail.openjdk.java.net/pipermail/jdk-updates-dev/2020-September/003816.html CSR: https://bugs.openjdk.java.net/browse/JDK-8253136
16-09-2020