8263976: Remove block allocation from BasicHashtable

[coleenp]

From CR:
The useful/general BasicHashtable uses a block allocation scheme to reportedly reduce fragmentation. When the StringTable and SymbolTable used to use this hashtable, performance benefits were reportedly observed because of the block allocation scheme. Since these tables were moved to the concurrent hashtables, the tables left that use the block allocation scheme are:

AdapterHandlerLibrary, ResolutionError, LoaderConstraints, Leak profiler bitset table and Placeholders. 3 of these tables are very small and never needed block allocation to prevent fragmentation at least. Also there are 3 KVHashtables, which are built from BasicHashtable. 2 are used during dumping and 1 is ID2KlassTable which appears small.

ModuleEntry, PackageEntry, Dictionary, G1RootSet for nmethods, and JvmtiTagMap tables didn't use the block allocation scheme.

Removing this removes 7 pointers per table, and for each ClassLoaderData, which has 3 tables, removes 21 pointers.

This change was performance tested on linux and windows.

It was also tested with tier1-6.

---

Progress

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Issue

• JDK-8263976: Remove block allocation from BasicHashtable

Reviewers

• Lois Foltan (@lfoltan - Reviewer) ⚠️ Review applies to 328f72c
• Ioi Lam (@iklam - Reviewer)

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[mlbridge]

Webrevs

• 01: Full - Incremental (7a0ad9e)
• 00: Full (328f72c)

[coleenp]

I forgot to add that we can eventually replace these tables with std::unordered_set once the allocation and other template parameters are decided on. There are also other cleanups that we could do with this code, ie. Hashtable isn't that different from BasicHashtable so really isn't needed. We could make the Entry type a template parameter. This change is only a step in this direction.

[lfoltan]

Great clean up Coleen! ModuleEntryTable and PackageEntryTable changes looks good as does the other changes as well.
Lois

[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:

8263976: Remove block allocation from BasicHashtable

Reviewed-by: lfoltan, iklam

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 5 new commits pushed to the master branch:

• f62b100: 8263895: Test nsk/jvmti/GetThreadGroupChildren/getthrdgrpchld001/getthrdgrpchld001.cpp uses incorrect indices
• f84b52b: 8263897: compiler/c2/aarch64/TestVolatilesSerial.java failed with "java.lang.RuntimeException: Wrong method"
• f08bf4b: 8263891: Changes for 8076985 missed the fix.
• b2df513: 8261785: Calling "main" method in anonymous nested class crashes the JVM
• 840ab7b: 8263894: Convert defaultPrinter and printers fields to local variables

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

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[iklam]

Looks good overall. Just some small nits.

[coleenp]

Thanks Lois and Ioi!
/integrate

[openjdk]

@coleenp Since your change was applied there have been 24 commits pushed to the master branch:

• fbd57bd: 8263260: [s390] Support latest hardware (z14 and z15)
• de2ff25: 8263974: Move SystemDictionary::verify_protection_domain
• 9dad857: 8263080: Obsolete relationship in MulticastSocket API documentation.
• 851474a: 8263649: AArch64: update cas.m4 to match current AD file
• fd3a33a: 8263189: C2: assert(!had_error) failed: bad dominance
• 7b81f8e: 8263915: runtime/cds/appcds/MismatchedPathTriggerMemoryRelease.java fails when UseCompressedClassPointers is off
• 2da882c: 8262465: Very long compilation times and high memory consumption in C2 debug builds
• 0b03d04: 8167015: compiler/codecache/jmx/PoolsIndependenceTest.java timeout
• df01b15: 8263977: GTK L&F: Cleanup duplicate checks in GTKStyle and GTKLookAndFeel
• 57d8f1d: 8263985: BCEscapeAnalyzer::invoke checks target->is_loaded() twice
• ... and 14 more: https://git.openjdk.java.net/jdk/compare/ba504fcee8ba9ca3e6c223effc46754444a9c49f...master

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