8332610: Remove unused nWakeups in ObjectMonitor #19326

jdksjolen · 2024-05-21T13:14:37Z

Hi,

This comment only serves to confuse people, as nWakeups is not shared between threads and never read. It is probably meant for debugging (not sure). Let's delete the comment.

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Issue

JDK-8332610: Remove unused nWakeups in ObjectMonitor (Enhancement - P4)

Reviewers

Coleen Phillimore (@coleenp - Reviewer)
Daniel D. Daugherty (@dcubed-ojdk - Reviewer) ⚠️ Review applies to f0de0bf1

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$ git checkout pull/19326

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$ git checkout pull/19326
$ git pull https://git.openjdk.org/jdk.git pull/19326/head

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$ git pr checkout 19326

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bridgekeeper · 2024-05-21T13:15:25Z

👋 Welcome back jsjolen! 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 · 2024-05-21T13:15:47Z

@jdksjolen 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:

8332610: Remove unused nWakeups in ObjectMonitor

Reviewed-by: coleenp, dcubed

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 29 new commits pushed to the master branch:

4f1a10f: 8332360: JVM hangs at exit when running on a uniprocessor
c3bc23f: 8326306: RISC-V: Re-structure MASM calls and jumps
8a9d77d: 8320622: [TEST] Improve coverage of compiler/loopopts/superword/TestMulAddS2I.java on different platforms
3d511ff: 8329748: Change default value of AssertWXAtThreadSync to true
67f03f2: 8332533: RISC-V: Enable vector variable shift instructions for machines with RVV
5f804b2: 8329825: Clarify the value type for java.net.SocketOptions.SO_LINGER
52eda79: 8332538: Switch off JIT memory limit check for TestAlignVectorFuzzer.java
d999b81: 8331572: Allow using OopMapCache outside of STW GC phases
8291c94: 8331224: ClassCastException in ObjectInputStream hides ClassNotFoundException
42e3c84: 8332086: Remove the usage of ServiceLoader in j.u.r.RandomGeneratorFactory
... and 19 more: https://git.openjdk.org/jdk/compare/b92bd671835c37cff58e2cdcecd0fe4277557d7f...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.

openjdk · 2024-05-21T13:16:22Z

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

hotspot-runtime

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 · 2024-05-21T13:19:15Z

Webrevs

coleenp

Please remove that unused variable also in the two places it's defined. There's a perf counter that does not use this variable so the comment above with TryLock does make sense wrt to that perf counter. This local variable is unused.

jdksjolen · 2024-05-21T14:40:13Z

Please remove that unused variable also in the two places it's defined. There's a perf counter that does not use this variable so the comment above with TryLock does make sense wrt to that perf counter. This local variable is unused.

nWakeups deleted!

coleenp

Looks great! Thank you for finding this unused code.

dcubed-ojdk

Thumbs up. This is a trivial fix.

dholmes-ora

Interestingly this code has been dead since it was introduced. I will assume it was leftover debugging/performance-monitoring code.

dholmes-ora · 2024-05-22T05:11:33Z

src/hotspot/share/runtime/objectMonitor.cpp

-    // Keep a tally of the # of futile wakeups.
-    // Note that the counter is not protected by a lock or updated by atomics.
-    // That is by design - we trade "lossy" counters which are exposed to
-    // races during updates for a lower probe effect.


The same comment block needs deleting at line 874 too.

Actually, I think the comment blocks are referring to the OM_PERFDATA_OP(FutileWakeups, inc()); calls not the nWakeups local variable.

dholmes-ora

Please restore comment, and possibly move them closer to the code the relate to.

Also nit: please change the bug synopsis to "Remove unused nWakeups in ObjectMonitor"

Thanks

jdksjolen · 2024-05-22T08:17:09Z

Please restore comment, and possibly move them closer to the code the relate to.

Also nit: please change the bug synopsis to "Remove unused nWakeups in ObjectMonitor"

Thanks

Good catch on both! I've fixed the issues, thanks.

coleenp

I would not have missed that comment, but it looks fine.

jdksjolen · 2024-05-22T13:51:35Z

Errors for maxos-x64 unrelated to this patch. Thanks Coleen, Dan and David.

/integrate

openjdk · 2024-05-22T13:52:52Z

Going to push as commit 9ca90cc.
Since your change was applied there have been 30 commits pushed to the master branch:

92d3350: 8331920: ubsan: g1CardSetContainers.inline.hpp:266:5: runtime error: index 2 out of bounds for type 'G1CardSetHowl::ContainerPtr [2]' reported
4f1a10f: 8332360: JVM hangs at exit when running on a uniprocessor
c3bc23f: 8326306: RISC-V: Re-structure MASM calls and jumps
8a9d77d: 8320622: [TEST] Improve coverage of compiler/loopopts/superword/TestMulAddS2I.java on different platforms
3d511ff: 8329748: Change default value of AssertWXAtThreadSync to true
67f03f2: 8332533: RISC-V: Enable vector variable shift instructions for machines with RVV
5f804b2: 8329825: Clarify the value type for java.net.SocketOptions.SO_LINGER
52eda79: 8332538: Switch off JIT memory limit check for TestAlignVectorFuzzer.java
d999b81: 8331572: Allow using OopMapCache outside of STW GC phases
8291c94: 8331224: ClassCastException in ObjectInputStream hides ClassNotFoundException
... and 20 more: https://git.openjdk.org/jdk/compare/b92bd671835c37cff58e2cdcecd0fe4277557d7f...master

Your commit was automatically rebased without conflicts.

openjdk · 2024-05-22T13:53:00Z

@jdksjolen Pushed as commit 9ca90cc.

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

dcubed-ojdk

I'm fine with the final version also.

Remove comment

f9b0d41

openjdk bot changed the title ~~8332610~~ 8332610: Remove confusing comment in ObjectMonitor::ReenterI May 21, 2024

openjdk bot added the rfr Pull request is ready for review label May 21, 2024

openjdk bot added the hotspot-runtime hotspot-runtime-dev@openjdk.org label May 21, 2024

coleenp suggested changes May 21, 2024

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Delete nWakeup

0727fbe

jdksjolen changed the title ~~8332610: Remove confusing comment in ObjectMonitor::ReenterI~~ 8332610 May 21, 2024

openjdk bot changed the title ~~8332610~~ 8332610: Remove unused nWakeups ObjectMonitor::ReenterI May 21, 2024

Delete the second nWakeups

f0de0bf

jdksjolen changed the title ~~8332610: Remove unused nWakeups ObjectMonitor::ReenterI~~ 8332610 May 21, 2024

openjdk bot changed the title ~~8332610~~ 8332610: Remove unused nWakeups ObjectMonitor May 21, 2024

coleenp approved these changes May 21, 2024

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openjdk bot added the ready Pull request is ready to be integrated label May 21, 2024

dcubed-ojdk approved these changes May 21, 2024

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dholmes-ora approved these changes May 22, 2024

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dholmes-ora reviewed May 22, 2024

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dholmes-ora suggested changes May 22, 2024

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Move the comments around

e43cb33

jdksjolen changed the title ~~8332610: Remove unused nWakeups ObjectMonitor~~ 8332610: Remove unused nWakeups in ObjectMonitor May 22, 2024

coleenp approved these changes May 22, 2024

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openjdk bot added the integrated Pull request has been integrated label May 22, 2024

openjdk bot closed this May 22, 2024

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels May 22, 2024

dcubed-ojdk reviewed May 22, 2024

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8332610: Remove unused nWakeups in ObjectMonitor #19326

8332610: Remove unused nWakeups in ObjectMonitor #19326

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8332610: Remove unused nWakeups in ObjectMonitor #19326

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jdksjolen commented May 21, 2024 • edited by openjdk bot Loading

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