8265682: G1: Mutex::_name dangling in HeapRegionRemSet references after JDK-8264146

[coleenp]

This change makes the Mutex constructor stdup the name passed in for the few cases that the name is constructed on the stack. Most names are shorter than 64 characters so it's still a savings.
Tested with tier1.

---

Progress

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Issue

• JDK-8265682: G1: Mutex::_name dangling in HeapRegionRemSet references after JDK-8264146

Reviewers

• David Holmes (@dholmes-ora - Reviewer) ⚠️ Review applies to fec5c8a
• Stefan Johansson (@kstefanj - Reviewer)

Reviewing

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[bridgekeeper]

👋 Welcome back coleenp! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (9baa7ae5)
• 00: Full (fec5c8af)

[dholmes-ora]

Hi Coleen,

LGTM.

The strdup may have a slight impact on startup, but no more so than the previous implementation, so I think at worst we are back where we were. And we still get the memory savings, which was the primary goal.

Thanks,
David

[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:

8265682: G1: Mutex::_name dangling in HeapRegionRemSet references after JDK-8264146

Reviewed-by: dholmes, sjohanss

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 31 new commits pushed to the master branch:

• b9f66d9: 8264188: Improve handling of assembly files in the JDK
• c3ac690: 8261759: ZGC: ZWorker Threads Continue Marking After System.exit() called
• 31abe68: 8265116: ZGC: Steal local stacks instead of flushing them
• 83364a4: 8264258: Unknown lookups in the java package give misleading compilation errors
• a9367db: 8265127: ZGC: Fix incorrect reporting of reclaimed memory
• 1580a47: 8265911: assert(comp != __null) failed: Compiler instance missing
• 9647fb0: 8265689: JVMCI: InternalError: Class java.lang.Object does not implement interface jdk.vm.ci.meta.JavaType
• 0d08d73: 8265702: ZGC on macOS/aarch64
• 45c5da0: 8265746: Update java.time to use instanceof pattern variable (part II)
• a85f6cb: 8265613: False positives for "Related Packages"
• ... and 21 more: https://git.openjdk.java.net/jdk/compare/891f72fe6ea545cdf845d26157a64315a93f9a06...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.

[kstefanj]

Looks good.

[coleenp]

Thanks David and Stefan for the reviews. The name is only used in debugging so if we had any reason to suspect performance regression we could ifdef it. I don't think it's worth doing that and it's good that it would be available in product right now.
Kim pointed out offline that I could use ASSERT_STREQ so I made the trivial change in the patch.

[kstefanj]

Still good, I don't think we should #ifdef it either.

[coleenp]

Thanks Stefan!
/integrate

[openjdk]

@coleenp Since your change was applied there have been 32 commits pushed to the master branch:

• 2b09ff2: 8232765: NullPointerException at Types.eraseNotNeeded() when compiling a class
• b9f66d9: 8264188: Improve handling of assembly files in the JDK
• c3ac690: 8261759: ZGC: ZWorker Threads Continue Marking After System.exit() called
• 31abe68: 8265116: ZGC: Steal local stacks instead of flushing them
• 83364a4: 8264258: Unknown lookups in the java package give misleading compilation errors
• a9367db: 8265127: ZGC: Fix incorrect reporting of reclaimed memory
• 1580a47: 8265911: assert(comp != __null) failed: Compiler instance missing
• 9647fb0: 8265689: JVMCI: InternalError: Class java.lang.Object does not implement interface jdk.vm.ci.meta.JavaType
• 0d08d73: 8265702: ZGC on macOS/aarch64
• 45c5da0: 8265746: Update java.time to use instanceof pattern variable (part II)
• ... and 22 more: https://git.openjdk.java.net/jdk/compare/891f72fe6ea545cdf845d26157a64315a93f9a06...master

Your commit was automatically rebased without conflicts.

Pushed as commit 222f9f0.

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