8270014: Add scoped objects for g1 young gc verification and young gc internal timing #4768

tschatzl · 2021-07-13T13:51:27Z

Hi all,

can I get reviews for some further cleanup of the young collection code:

adding some more scoped objects (verification, gc pause timing)
some naming, minor related code movement

Thanks,
Thomas

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JDK-8270014: Add scoped objects for g1 young gc verification and young gc internal timing

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Albert Mingkun Yang (@albertnetymk - Committer) ⚠️ Review applies to b9b53f8
Ivan Walulya (@walulyai - Committer) ⚠️ Review applies to b6be6fc
Kim Barrett (@kimbarrett - Reviewer)

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bridgekeeper · 2021-07-13T13:51:50Z

👋 Welcome back tschatzl! 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 · 2021-07-13T13:55:29Z

@tschatzl The following label will be automatically applied to this pull request:

hotspot-gc

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mlbridge · 2021-07-13T13:59:06Z

Webrevs

albertnetymk · 2021-07-13T18:15:57Z

src/hotspot/share/gc/g1/g1GCPhaseTimes.cpp

 void G1GCPhaseTimes::print() {
-  note_gc_end();
-
  if (_cur_verify_before_time_ms > 0.0) {


Is this if just checking whether verification is enabled or not? If so, can VerifyBeforeGC be used? Otherwise, it's unclear to me why we are comparing it with 0.0.

The if checks whether any verification work has been done (it will be > 0.0 if it has been set) in this pause. We can't just use VerifyBefore/AfterGC because verification before/after does not always run for all young gc pauses (see VerifyGCType).
If we want to change this (existing) behavior to like always print the time if the flag is enabled I would suggest to file another CR instead of hiding it here (I can do all that and the associated work if that is desired).

We can't just use VerifyBefore/AfterGC because...

I see; thank you for the explanation.

If we want to change this (existing) behavior to like always print the time if the flag is enabled

Either that or just put some comment there, since in what situation the condition is true is not obvious. Ofc, this is very subjective.

albertnetymk · 2021-07-13T18:21:16Z

src/hotspot/share/gc/g1/g1Policy.hpp

+  void note_young_gc_pause_start();
+  void note_young_gc_pause_end();


It's not obvious to me if there's a diff btw young_gc_pause and young_collection, or what the diff is. I think having some comments for these two pairs of methods would make it easier to understand.

Added comments. gc_pause is the whole pause, collection is about just the collection part (as defined by the inner scope of the do_collection_pause_at_safepoint_helper). Feel free to suggest better naming.

Maybe something like record_young_collection_work_start; another question is whether we should keep the note_ prefix for the pause or change it to record_ as well as it seems quite common.

I suggest we change to record_

walulyai

lgtm!

kimbarrett · 2021-07-15T07:12:28Z

src/hotspot/share/gc/g1/g1Policy.cpp


-  double end_time_sec = os::elapsedTime();
-  double start_time_sec = phase_times()->cur_collection_start_sec();
+  double start_time_s = phase_times()->cur_collection_start_sec();


I dislike this change of nomenclature to use _s suffix instead of _sec suffix to indicate units of seconds. The latter is in wide use in GC code.

kimbarrett

Looks good.

openjdk · 2021-07-15T08:09:26Z

@tschatzl 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:

8270014: Add scoped objects for g1 young gc verification and young gc internal timing

Reviewed-by: ayang, iwalulya, kbarrett

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 34 new commits pushed to the master branch:

1ebd946: 8270333: -XX:+VerifyStringTableAtExit should not do linear search
04b73bc: 8269656: The test test/langtools/tools/javac/versions/Versions.java has duplicate test cycles
7c23491: 8269598: Regressions up to 5% on aarch64 seems due to JDK-8268858
7d0edb5: Merge
7b4d84c: 8270422: Test build/AbsPathsInImage.java fails after JDK-8259848
72db09b: 8266313: (JEP-356) - RandomGenerator spec implementation requirements tightly coupled to JDK internal classes
3bbd233: 8270075: SplittableRandom extends AbstractSplittableGenerator
381bd62: 8266889: [macosx-aarch64] Crash with SIGBUS in MarkActivationClosure::do_code_blob during vmTestbase/nsk/jvmti/.../bi04t002 test run
82c256e: 8259499: Handling type arguments from outer classes for inner class in javadoc
e5db9a9: 8268620: InfiniteLoopException test may fail on x86 platforms
... and 24 more: https://git.openjdk.java.net/jdk/compare/375fc2a2b29c454b36d3ae068a080b28f6ec04e9...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.

tschatzl · 2021-07-15T08:11:00Z

Thanks @albertnetymk @walulyai @kimbarrett for your reviews.

/integrate

openjdk · 2021-07-15T08:12:45Z

Going to push as commit 7a89ffe.
Since your change was applied there have been 35 commits pushed to the master branch:

793d772: 8270475: Remove unused G1STWDrainQueueClosure
1ebd946: 8270333: -XX:+VerifyStringTableAtExit should not do linear search
04b73bc: 8269656: The test test/langtools/tools/javac/versions/Versions.java has duplicate test cycles
7c23491: 8269598: Regressions up to 5% on aarch64 seems due to JDK-8268858
7d0edb5: Merge
7b4d84c: 8270422: Test build/AbsPathsInImage.java fails after JDK-8259848
72db09b: 8266313: (JEP-356) - RandomGenerator spec implementation requirements tightly coupled to JDK internal classes
3bbd233: 8270075: SplittableRandom extends AbstractSplittableGenerator
381bd62: 8266889: [macosx-aarch64] Crash with SIGBUS in MarkActivationClosure::do_code_blob during vmTestbase/nsk/jvmti/.../bi04t002 test run
82c256e: 8259499: Handling type arguments from outer classes for inner class in javadoc
... and 25 more: https://git.openjdk.java.net/jdk/compare/375fc2a2b29c454b36d3ae068a080b28f6ec04e9...master

Your commit was automatically rebased without conflicts.

openjdk · 2021-07-15T08:13:07Z

@tschatzl Pushed as commit 7a89ffe.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

Initial implementation: further refactoring

c321d38

openjdk bot added the rfr Pull request is ready for review label Jul 13, 2021

openjdk bot added the hotspot-gc hotspot-gc-dev@openjdk.org label Jul 13, 2021

Fix test because of slightly different log message order

7730aa6

albertnetymk suggested changes Jul 13, 2021

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ayang review

b9b53f8

albertnetymk approved these changes Jul 14, 2021

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Change note_ to record_

b6be6fc

walulyai approved these changes Jul 14, 2021

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kimbarrett suggested changes Jul 15, 2021

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kbarrett review

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kimbarrett approved these changes Jul 15, 2021

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openjdk bot added the ready Pull request is ready to be integrated label Jul 15, 2021

openjdk bot closed this Jul 15, 2021

openjdk bot added integrated Pull request has been integrated and removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Jul 15, 2021

tschatzl deleted the submit/8270014-scope-objects-verification-3 branch July 15, 2021 08:31

		void note_young_gc_pause_start();
		void note_young_gc_pause_end();

8270014: Add scoped objects for g1 young gc verification and young gc internal timing #4768

8270014: Add scoped objects for g1 young gc verification and young gc internal timing #4768

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