Bug ID: JDK-8318720 G1: Memory leak in G1CodeRootSet after JDK-8315503

Type: Bug
Component: hotspot
Sub-Component: gc
Affected Version: 22

Priority: P3
Status: Resolved
Resolution: Fixed

Submitted: 2023-10-24
Updated: 2024-04-19
Resolved: 2023-10-25

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JDK 21	JDK 22
21.0.4-oracleFixed	22 b22Fixed

JDK-8315503 replaced ResourceHashTable with ConcurrentHashTable.
When it tries to clear G1CodeRootSetHashTable, it calls ConcurrentHashTable:table.unsafe_reset(). 

The method has comments states:
 // Unsafe reset and resize the table. This method assumes that we
  // want to clear and maybe resize the internal table without the
  // overhead of clearing individual items in the table. 

So, if the table is not empty, then all entries in table are leaked.

A pull request was submitted for review. URL: https://git.openjdk.org/jdk21u-dev/pull/476 Date: 2024-04-08 20:00:14 +0000
10-04-2024
Fix request [21u] I backport this for parity with 21.0.4-oracle. Required follow-up of JDK-8315503 and included in that backport. Clean backport.
08-04-2024
Changeset: 811b436e Author: Zhengyu Gu <zgu@openjdk.org> Date: 2023-10-25 23:47:46 +0000 URL: https://git.openjdk.org/jdk/commit/811b436e5de972bedd3a0fa25952b2e1beddd9c3
25-10-2023
A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/16352 Date: 2023-10-24 23:04:28 +0000
24-10-2023

Relates :	JDK-8315503 - G1: Code root scan causes long GC pauses due to imbalanced iteration
Relates :	JDK-8326092 - Pause Remark sometimes has extremely long pause times on class unloading