8273476: G1: refine G1CollectedHeap::par_iterate_regions_array_part_from #5414

Hamlin-Li · 2021-09-08T11:56:14Z

G1CollectedHeap::par_iterate_regions_array_part_from is moved from G1CollectionSet::iterate_part_from in JDK-8254167.
The parameters and logic of this method could be refined a bit to make it more straight.

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JDK-8273476: G1: refine G1CollectedHeap::par_iterate_regions_array_part_from

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Albert Mingkun Yang (@albertnetymk - Reviewer)
Thomas Schatzl (@tschatzl - Reviewer) ⚠️ Review applies to 46d5a3c

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bridgekeeper · 2021-09-08T11:57:13Z

👋 Welcome back mli! 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 · 2021-09-08T11:59:38Z

@Hamlin-Li The following label will be automatically applied to this pull request:

hotspot-gc

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

mlbridge · 2021-09-08T12:03:16Z

Webrevs

albertnetymk · 2021-09-08T12:17:44Z

src/hotspot/share/gc/g1/g1CollectedHeap.hpp

  // Iterate part of an array of region indexes given by offset and length, applying
  // the given HeapRegionClosure on each region. The worker_id will determine where
  // in the part to start the iteration to allow for more efficient parallel iteration.
  void par_iterate_regions_array_part_from(HeapRegionClosure* cl,


The comment needs to be updated as well. const uint* regions can be written as const uint regions[] to make the concept clearer, IMO.

I have modified the function name too.

openjdk · 2021-09-08T12:18:50Z

@Hamlin-Li 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:

8273476: G1: refine G1CollectedHeap::par_iterate_regions_array_part_from

Reviewed-by: ayang, tschatzl

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:

aa93111: 8273483: Zero: Clear pending JNI exception check in native method handler
8c16f48: 8273487: Zero: Handle "zero" variant in runtime tests
dc33bd8: 8273315: Parallelize and increase timeouts for java/foreign/TestMatrix.java test
5b1dfe4: 8273439: Fix G1CollectedHeap includes and forward declarations
6eba443: 8273387: remove some unreferenced gtk-related functions
5df2648: 8273218: G1: Rename g1EvacuationInfo to g1EvacInfo
12f0b77: 8273516: ProblemList compiler/c2/Test7179138_1.java in -Xcomp mode on win-X64
7fd6b0b: 8273242: (test) Refactor to use TestNG for RuntimeTests ExecCommand tests
a5e4def: 8265489: Stress test times out because of long ObjectSynchronizer::monitors_iterate(...) operation
9b5991e: 8273451: Remove unreachable return in mutexLocker::wait
... and 15 more: https://git.openjdk.java.net/jdk/compare/a66629a464b97176bcdc2ca1150d12df6241dc1c...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 · 2021-09-08T12:25:35Z

src/hotspot/share/gc/g1/g1CollectionSet.cpp

+  _g1h->par_iterate_regions_array_part_from(cl,
+                                            hr_claimer,
+                                            &_collection_set_regions[offset],
+                                            length-offset,


please add spaces around the - operator.

tschatzl

Lgtm.

tschatzl · 2021-09-09T08:05:46Z

src/hotspot/share/gc/g1/g1CollectionSet.cpp

+  _g1h->par_iterate_regions_array(cl,
+                                  hr_claimer,
+                                  &_collection_set_regions[offset],
+                                  length,


This should be length - offset, shouldn't it?

Suggested change

length,

length - offset,

Untested :)

I thought so too at first, but seems it's not.
The passed in length in both G1CollectionSet::par_iterate/iterate_incremental_part_from are both the length of the "sub" array already. ( increment_length() is passed as length in iterate_incremental_part_from)
How do you think about it?

You are right.

albertnetymk · 2021-09-09T08:11:27Z

src/hotspot/share/gc/g1/g1CollectedHeap.hpp

  }
  void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id);
-  // Iterate part of an array of region indexes given by offset and length, applying
+  // Iterate an array of region indexes given by offset and length, applying


Since there's no offset in the signature, how about "Iterate over the array, uint regions[length], applying ..."?

tschatzl · 2021-09-09T09:16:29Z

src/hotspot/share/gc/g1/g1CollectionSet.cpp

+  _g1h->par_iterate_regions_array(cl,
+                                  hr_claimer,
+                                  &_collection_set_regions[offset],
+                                  length,


You are right.

Hamlin-Li · 2021-09-09T09:33:07Z

I cancel the pre-submit tests for "Refine comments", the last successful run is at here https://github.com/Hamlin-Li/jdk/actions/runs/1216226352

Please kindly let me know if you have other comments, else I will push this later.

Hamlin-Li · 2021-09-09T10:39:55Z

Thanks for your reviews, @tschatzl @albertnetymk

Hamlin-Li · 2021-09-09T10:40:05Z

/integrate

openjdk · 2021-09-09T10:41:39Z

Going to push as commit 9690df7.
Since your change was applied there have been 26 commits pushed to the master branch:

00e059d: 8133686: HttpURLConnection.getHeaderFields and URLConnection.getRequestProperties methods return field values in reverse order
aa93111: 8273483: Zero: Clear pending JNI exception check in native method handler
8c16f48: 8273487: Zero: Handle "zero" variant in runtime tests
dc33bd8: 8273315: Parallelize and increase timeouts for java/foreign/TestMatrix.java test
5b1dfe4: 8273439: Fix G1CollectedHeap includes and forward declarations
6eba443: 8273387: remove some unreferenced gtk-related functions
5df2648: 8273218: G1: Rename g1EvacuationInfo to g1EvacInfo
12f0b77: 8273516: ProblemList compiler/c2/Test7179138_1.java in -Xcomp mode on win-X64
7fd6b0b: 8273242: (test) Refactor to use TestNG for RuntimeTests ExecCommand tests
a5e4def: 8265489: Stress test times out because of long ObjectSynchronizer::monitors_iterate(...) operation
... and 16 more: https://git.openjdk.java.net/jdk/compare/a66629a464b97176bcdc2ca1150d12df6241dc1c...master

Your commit was automatically rebased without conflicts.

openjdk · 2021-09-09T10:41:51Z

@Hamlin-Li Pushed as commit 9690df7.

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

refine par_iterate_regions_array_part_from

6292fd2

openjdk bot added the rfr Pull request is ready for review label Sep 8, 2021

openjdk bot added the hotspot-gc hotspot-gc-dev@openjdk.org label Sep 8, 2021

albertnetymk approved these changes Sep 8, 2021

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tschatzl suggested changes Sep 8, 2021

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Hamlin-Li added 3 commits September 9, 2021 08:51

refine comments and code

78da4ce

Fix assert

489947a

Fix issue

46d5a3c

tschatzl approved these changes Sep 9, 2021

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tschatzl suggested changes Sep 9, 2021

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albertnetymk reviewed Sep 9, 2021

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tschatzl approved these changes Sep 9, 2021

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Refine comments

af020d6

albertnetymk approved these changes Sep 9, 2021

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openjdk bot closed this Sep 9, 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 Sep 9, 2021

Hamlin-Li deleted the refine-G1CollectedHeap-par_iterate_regions_array_part_from branch September 11, 2021 00:55

8273476: G1: refine G1CollectedHeap::par_iterate_regions_array_part_from #5414

8273476: G1: refine G1CollectedHeap::par_iterate_regions_array_part_from #5414

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