8297495: j.u.concurrent updates for JDK 20 #11319

AlanBateman · 2022-11-23T12:40:05Z

The proposed updates for JDK 20 are:

ForkJoinPool.externalSubmit
ForkJoinWorkerThread.getQueuedTaskCount

These methods will be used to improve the Thread.yield implementation for virtual threads. The range of alternatives explored include not exposing an API and protected methods such as "offerSubmission". The class description speaks of "external clients" and "submissions from non-ForkJoinTask clients", hence the proposed naming and javadoc text.

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Issues

JDK-8297495: j.u.concurrent updates for JDK 20
JDK-8297648: j.u.concurrent updates for JDK 20 (CSR)

Reviewers

Jaikiran Pai (@jaikiran - Reviewer)

Reviewing

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$ git fetch https://git.openjdk.org/jdk pull/11319/head:pull/11319
$ git checkout pull/11319

Update a local copy of the PR:
$ git checkout pull/11319
$ git pull https://git.openjdk.org/jdk pull/11319/head

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$ git pr checkout 11319

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bridgekeeper · 2022-11-23T12:41:29Z

👋 Welcome back alanb! 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 · 2022-11-23T12:45:03Z

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

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AlanBateman · 2022-11-24T16:50:49Z

/csr

openjdk · 2022-11-24T16:52:34Z

@AlanBateman has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@AlanBateman please create a CSR request for issue JDK-8297495 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

mlbridge · 2022-11-28T10:55:00Z

Webrevs

01: Full - Incremental (a1ee40e5)
00: Full (b1415b2e)

jaikiran

I don't have enough knowledge of this area, but the API changes look OK to me.
With this addition of the externalSubmit method should the javadoc of the existing submit method be enhanced a bit to explain how it behaves differently as compared to this one and when to choose one over the other. For example, should submit API state (its already existing behaviour) that it will use the current worker thread's queue to push this new task if called from the worker thread?

jaikiran · 2022-11-29T06:50:02Z

test/jdk/java/util/concurrent/tck/ForkJoinPool20Test.java

+/**
+ * Tests for ForkJoinPool and ForkJoinWorkerThread additions in JDK 20.
+ */
+public class ForkJoinPool20Test extends JSR166TestCase {


The new externalSubmit API states:

@implSpec
This method is equivalent to {@link #submit(ForkJoinTask)} when called
from a thread that is not in this pool.

Should this new test class include a test which verifies this behaviour? As far as I can see, the new test methods that assert the queue counts are being invoked from within a worker thread.

jaikiran

Thank you for the changes. This looks fine to me.

openjdk · 2022-12-05T06:29:51Z

@AlanBateman 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:

8297495: j.u.concurrent updates for JDK 20

Reviewed-by: jpai

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 69 new commits pushed to the master branch:

b49fd92: 8298055: AArch64: fastdebug build fails after JDK-8247645
914ef07: 8297609: Add application/wasm MIME type for wasm file extension
a71d91b: 8298067: Persistent test failures after 8296012
87572d4: 8298068: ProblemList tests failing due to JDK-8297235
0edb5d0: 8297683: Use enhanced-for cycle instead of Enumeration in java.security.jgss
c67166f: 8298003: NMT: fatal block printout does not show the correct corruption address
99e2ef4: 8298054: ProblemList jdk/jfr/api/consumer/recordingstream/TestStop.java
6065516: 8291418: adjust monitor deflation logging and deflate_idle_monitors use
6e54705: 8295424: adjust timeout for another JLI GetObjectSizeIntrinsicsTest.java subtest
562bc17: 8291359: Specification of method j.l.foreign.VaList::skip still deserves clarification
... and 59 more: https://git.openjdk.org/jdk/compare/be4245e814cc29701cc425d8e66854e36eb3aef0...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.

viktorklang-ora · 2022-12-05T10:16:22Z

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java

+     *         scheduled for execution
+     * @since 20
+     */
+    public <T> ForkJoinTask<T> externalSubmit(ForkJoinTask<T> task) {


@AlanBateman Does it make sense to check the nullness of the task before going into the storeStoreFence etc?

It's only to be the same as poolSubmit.

@AlanBateman Then I presume that there's a good reason for not checking. :)

AlanBateman · 2022-12-05T15:18:39Z

/integrate

openjdk · 2022-12-05T15:20:30Z

Going to push as commit 19d8498.
Since your change was applied there have been 87 commits pushed to the master branch:

3288459: 8297606: [AIX] Broken build after JDK-8295475
0452c39: 8296477: Foreign linker implementation update following JEP 434
73baadc: 8295044: Implementation of Foreign Function and Memory API (Second Preview)
bd38188: 8297766: Remove UseMallocOnly development option
b9eec96: 8281214: Unsafe use of long in VMThread::setup_periodic_safepoint_if_needed
e7e0354: 8297767: Assert JNICritical_lock/safepoint-1 and AdapterHandlerLibrary_lock/safepoint-1
f9e0f1d: 8297763: Fix missing stub code expansion before align() in shared trampolines
2300ed4: 8291769: Translation of switch with record patterns could be improved
eab0ada: 8296545: C2 Blackholes should allow load optimizations
dea2161: 8297959: Provide better descriptions for some Operating System JFR events
... and 77 more: https://git.openjdk.org/jdk/compare/be4245e814cc29701cc425d8e66854e36eb3aef0...master

Your commit was automatically rebased without conflicts.

openjdk · 2022-12-05T15:20:56Z

@AlanBateman Pushed as commit 19d8498.

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

Initial commit

7ba9ce0

openjdk bot added the core-libs core-libs-dev@openjdk.org label Nov 23, 2022

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f776943

openjdk bot added the csr Pull request needs approved CSR before integration label Nov 24, 2022

Improve javadoc

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AlanBateman marked this pull request as ready for review November 28, 2022 10:50

openjdk bot added the rfr Pull request is ready for review label Nov 28, 2022

jaikiran reviewed Nov 29, 2022

View reviewed changes

AlanBateman added 3 commits November 30, 2022 14:40

Merge

1b9694a

Adjust wording to make it clear that the number of tasks is non-negative

09bc76d

Expand test

a1ee40e

openjdk bot removed the csr Pull request needs approved CSR before integration label Dec 1, 2022

jaikiran approved these changes Dec 5, 2022

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openjdk bot added the ready Pull request is ready to be integrated label Dec 5, 2022

viktorklang-ora reviewed Dec 5, 2022

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openjdk bot added the integrated Pull request has been integrated label Dec 5, 2022

openjdk bot closed this Dec 5, 2022

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Dec 5, 2022

He-Pin mentioned this pull request Feb 18, 2023

[WIP] attempt to use external submission for rescheduling of actor mailboxes akka/akka#31156

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He-Pin mentioned this pull request Sep 20, 2023

ForkJoinPoolStarvationSpec apache/pekko#661

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8297495: j.u.concurrent updates for JDK 20 #11319

8297495: j.u.concurrent updates for JDK 20 #11319

AlanBateman commented Nov 23, 2022 •

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8297495: j.u.concurrent updates for JDK 20 #11319

8297495: j.u.concurrent updates for JDK 20 #11319

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