JDK-8320525 : G1: G1UpdateRemSetTrackingBeforeRebuild::distribute_marked_bytes accesses partially unloaded klass
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 22
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2023-11-21
  • Updated: 2024-04-23
  • Resolved: 2023-11-28
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JDK 22
22 b26Fixed
Related Reports
Blocks :  
JDK-8317809 - Insertion of free code blobs into code cache can be very slow during class unloading
Description
For debug purposes G1UpdateRemSetTrackingBeforeRebuild::distribute_marked_bytes() accesses the size of the humongous object it is currently processing.

In case of marked_bytes == 0, the object is actually dead, and the code should not access the klass any more.

This currently does not matter because we purge the metaspace for unloaded classes after this code, but still this is ugly.

Makes code that moves the purging before G1UpdateRemSetTrackingBeforeRebuild crash on some platforms (linux-x86).
Comments
Fix request [21u] I backport this as prereq of JDK-8317809. Low risk, modifies an assertion. Clean backport. SAP nig SAP nightly testing passed.htly testing passed.
23-04-2024
A pull request was submitted for review. URL: https://git.openjdk.org/jdk21u-dev/pull/517 Date: 2024-04-22 07:36:39 +0000
22-04-2024
Changeset: 21d361e9 Author: Thomas Schatzl <tschatzl@openjdk.org> Date: 2023-11-28 20:55:27 +0000 URL: https://git.openjdk.org/jdk/commit/21d361e944a599e82e5ed93aa81ad485b4601843
28-11-2023
A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/16766 Date: 2023-11-21 16:01:39 +0000
21-11-2023