JDK-8332420 : Regression in DaCapo-fop-default on linux-x64
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 21.0.4
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • OS: linux
  • CPU: x86_64
  • Submitted: 2024-05-16
  • Updated: 2025-11-19
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JDK 21
21-poolUnresolved
Related Reports
Relates :  
JDK-8315503 - G1: Code root scan causes long GC pauses due to imbalanced iteration
Relates :  
JDK-8358342 - G1: G1CodeRootSet performance breaks down on even moderate load
Description
4% benchmark regression in DaCapo-fop-default on linux-x64 in 21.0.4-b02

Regression has been narrowed down to CI builds, either:
• jdk-21.0.4+1-218 , or
• jdk-21.0.4+1-219
Comments
Most likely related to JDK-8358342 which is also a performance problem. Not sure why it would only show up on 21.
19-11-2025
Does not seem to be same issue as JDK-8358342, some local testing did not show that large differences in either Code Root Scan or total pause times, particularly with fixed max heap size
19-11-2025
Sorry for the long delay in answering, it just got lost in the automatied jira notifications. No, there is no follow-up performance fix for JDK-8315503 I am aware of right now, there were only some lock ranking issues that were backported.
03-09-2025
> This relates to the code root iteration changes backport to jdk21 to fix overall performance. The same changes in 22 did not show a regression. [~tschatzl] Does it sound like a JDK-8315503 backport issue? Or it may be required to backport more related fixes in 22?
17-04-2025
JDK-8315503 is the most likely cause for the regression.
29-05-2024
This relates to the code root iteration changes backport to jdk21 to fix overall performance. The same changes in 22 did not show a regression.
17-05-2024
Regression hold into following builds. Regression starts somewhere in CI builds: jdk-21.0.4+1-217 to jdk-21.0.4+1-220 Unfortunately, there are no builds for 217, 218, and 219, so we cannot determine the exact build it starts in. However: --- 217 only includes JDK-8317809, and 220 only includes JDK-8329524 which backs-out the 217 fix. --- 220 still shows the regression, so we can eliminate 217 and 220 as the cause. Leaving as the cause as: 218 (contains 4 fixes) or 219 (contains 1 fix) All changes in 218 and 219 are by Thomas, so we'll leave you to decide which is the cause.
16-05-2024