JDK-8315504 : G1: Improve class unloading logging
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 22
  • Priority: P4
  • Status: Closed
  • Resolution: Duplicate
  • Submitted: 2023-09-01
  • Updated: 2024-02-23
  • Resolved: 2024-02-23
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tbdResolved
Related Reports
Duplicate :  
JDK-8317809 - Insertion of free code blobs into code cache can be very slow during class unloading
Description
Recent investigation in long Remark pauses showed that a considerable part of the "Class Unloading" part is not logged, leading to logs like this:

Class unloading part breakdown:
[1384,331s][gc,phases      ] GC(72) ClassLoaderData 53,370ms     <--- clean CLDs/identify dead CLDs
[1384,331s][gc,phases      ] GC(72) Trigger cleanups 0,006ms
[1384,557s][gc,phases      ] GC(72) Complete Cleaning 225,582ms  <--- clean code cache/identify dead nmethods
[1391,343s][gc,phases      ] GC(72) Class Unloading 7065,470ms

I.e. out of the 7000ms of Class Unloading, only 270ms are actually accounted for in the logs.

Improve upon that.
Comments
JDK-8317809 added complete per-phase logging for class unloading, so closing this as duplicate.
23-02-2024