8267752: KVHashtable doesn't deallocate entries

[coleenp]

Add a free_entry iteration to the destructor of ~KVHashtables.
Tested with tier1-3.

---

Progress

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Issue

• JDK-8267752: KVHashtable doesn't deallocate entries

Reviewers

• Ioi Lam (@iklam - Reviewer)
• Thomas Stuefe (@tstuefe - Reviewer)

Reviewing

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (b5c69590)

[openjdk]

@coleenp This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8267752: KVHashtable doesn't deallocate entries

Reviewed-by: iklam, stuefe

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 25 new commits pushed to the master branch:

• 3ad6586: 8268078: ClassListParser::_interfaces should be freed
• 48d4562: 8268780: Use 'print_cr' instead of 'print' for the message 'eliminated '
• e0f6f70: Merge
• 788b309: 8268768: idea.sh has been updated in surprising and incompatible ways
• 9ac0609: 8268828: ProblemList compiler/intrinsics/VectorizedMismatchTest.java on win-x64
• fe7a44d: 8268723: Problem list SA core file tests on OSX when using ZGC
• 31a055e: 8268736: Use apiNote in AutoCloseable.close javadoc
• 76cad4b: 8263321: Regression 8% in javadoc-steady in 17-b11
• e36136f: 8268125: ZGC: Clone oop array gets wrong acopy stub
• 35d867d: 8268663: Crash when guards contain boolean expression
• ... and 15 more: https://git.openjdk.java.net/jdk/compare/17295b1bb02b2121978f1459b2e75c5e1031e7ea...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[tstuefe]

Hi Coleen,

seems to be right.

I did a little test (filling a KV<int, int> hashtable with 500mio entries and releasing it) and was confused when RSS did not go down es expected; but this seems to be a glibc issue (repeating the test did not allocate twice as much memory, so the second round of mallocs reused the first frees).

(Update: this is entirely an glibc issue of not releasing memory to the OS)

See my question inline about unlink(). Otherwise this is fine. This was only ever used in CDS dumping, right?

Cheers, Thomas

[coleenp]

Thanks Ioi and Thomas for the code reviews.
/integrate

[openjdk]

Going to push as commit 72b3b0a.
Since your change was applied there have been 26 commits pushed to the master branch:

• af13fe1: 8267870: Remove unnecessary char_converter during class loading
• 3ad6586: 8268078: ClassListParser::_interfaces should be freed
• 48d4562: 8268780: Use 'print_cr' instead of 'print' for the message 'eliminated '
• e0f6f70: Merge
• 788b309: 8268768: idea.sh has been updated in surprising and incompatible ways
• 9ac0609: 8268828: ProblemList compiler/intrinsics/VectorizedMismatchTest.java on win-x64
• fe7a44d: 8268723: Problem list SA core file tests on OSX when using ZGC
• 31a055e: 8268736: Use apiNote in AutoCloseable.close javadoc
• 76cad4b: 8263321: Regression 8% in javadoc-steady in 17-b11
• e36136f: 8268125: ZGC: Clone oop array gets wrong acopy stub
• ... and 16 more: https://git.openjdk.java.net/jdk/compare/17295b1bb02b2121978f1459b2e75c5e1031e7ea...master

Your commit was automatically rebased without conflicts.

[openjdk]

@coleenp Pushed as commit 72b3b0a.

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