8289822: G1: Make concurrent mark code owner of TAMSes

[tschatzl]

Hi all,

please review this change that moves TAMS ownership and handling out of HeapRegion into G1ConcurrentMark.

The rationale is that it's intrinsically a data structure only used by the marking, and only interesting during marking, so attaching it to the always present HeapRegion isn't fitting.

This also moves some code that is about marking decisions out of HeapRegion.

In this change the TAMSes are still maintained and kept up to date as long as the HeapRegion exists (basically always) as the snapshotting of the marking does not really snapshot ("copy over the HeapRegions that existed at the time of the snapshot, only ever touching them), but assumes that they exist even for uncommitted (or free) regions due to the way it advances the global finger pointer.
I did not want to change this here.

This is also why HeapRegion still tells G1ConcurrentMark to update the TAMS in two places (when clearing a region and when resetting during full gc).

Another option I considered when implementing this is clearing all marking statistics (G1ConcurrentMark::clear_statistics) at these places in HeapRegion because it decreases the amount of places where this needs to be done (maybe one or the other place isn't really necessary already). I rejected it because this would add some work that is dependent on the number of worker threads (particularly) into HeapRegion::hr_clear(). This change can be looked at by viewing at all but the last commit.

Testing: tier1-4, gha

Thanks,
Thomas

---

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Issue

• JDK-8289822: G1: Make concurrent mark code owner of TAMSes (Enhancement - P4)

Reviewers

• Albert Mingkun Yang (@albertnetymk - Reviewer) ⚠️ Review applies to fae12ca0
• Ivan Walulya (@walulyai - Reviewer) ⚠️ Review applies to fae12ca0

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Webrevs

• 05: Full - Incremental (22d0407c)
• 04: Full - Incremental (fae12ca0)
• 03: Full - Incremental (652330cd)
• 02: Full - Incremental (f0afe153)
• 01: Full (4c618dc7)
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[albertnetymk]

/label add hotspot-gc

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git checkout submit/8289822-concurrent-mark-tams-owner
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git commit -m "Merge master"
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[openjdk]

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

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8289822: G1: Make concurrent mark code owner of TAMSes

Reviewed-by: ayang, iwalulya

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At the time when this comment was updated there had been 79 new commits pushed to the master branch:

• 5b6b514: 8325362: Allow to create a simple in-memory input JavaFileObject
• c59c41a: 8326941: Remove StringUTF16::isBigEndian
• 6eea5d6: 8325187: JVMTI GetThreadState says virtual thread is JVMTI_THREAD_STATE_INTERRUPTED when it no longer is
• 053ff76: 8308660: C2 compilation hits 'node must be dead' assert
• e1b0af2: 8323972: C2 compilation fails with assert(!x->as_Loop()->is_loop_nest_inner_loop()) failed: loop was transformed
• c0fc956: 8328275: CodeCache::print_internals should not be called in PRODUCT code
• 4ef591f: 8326964: Remove Eclipse Shared Workspaces
• ac5b6cb: 8327757: Convert javax/swing/JSlider/6524424/bug6524424.java applet to main
• 652fb3a: 8328154: Convert sun/java2d/loops/CopyAreaSpeed.java applet test to main
• 9059727: 8327182: Move serverAlias into the loop
• ... and 69 more: https://git.openjdk.org/jdk/compare/49ce85fae9f06d05367c94615532f6ff87952c79...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.

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[albertnetymk]

Maybe add G1: in the title?

[walulyai]

LGTM!

[tschatzl]

Thanks @albertnetymk @walulyai for your reviews
/integrate

[openjdk]

Going to push as commit f1c69cc.
Since your change was applied there have been 79 commits pushed to the master branch:

• 5b6b514: 8325362: Allow to create a simple in-memory input JavaFileObject
• c59c41a: 8326941: Remove StringUTF16::isBigEndian
• 6eea5d6: 8325187: JVMTI GetThreadState says virtual thread is JVMTI_THREAD_STATE_INTERRUPTED when it no longer is
• 053ff76: 8308660: C2 compilation hits 'node must be dead' assert
• e1b0af2: 8323972: C2 compilation fails with assert(!x->as_Loop()->is_loop_nest_inner_loop()) failed: loop was transformed
• c0fc956: 8328275: CodeCache::print_internals should not be called in PRODUCT code
• 4ef591f: 8326964: Remove Eclipse Shared Workspaces
• ac5b6cb: 8327757: Convert javax/swing/JSlider/6524424/bug6524424.java applet to main
• 652fb3a: 8328154: Convert sun/java2d/loops/CopyAreaSpeed.java applet test to main
• 9059727: 8327182: Move serverAlias into the loop
• ... and 69 more: https://git.openjdk.org/jdk/compare/49ce85fae9f06d05367c94615532f6ff87952c79...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit f1c69cc.

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