8268906: gc/g1/mixedgc/TestOldGenCollectionUsage.java assumes that GCs take 1ms minimum

[tschatzl]

Hi,

can I have reviews for this change to a test that incorrectly assumed that GCs take 1ms minimum?

At the end of the test, MXBeans' getCollectionTime() is compared against one taken two gcs earlier. If these two gcs are very short, getCollectionTime() returns the same value as before because its resolution is 1ms.

The getCollectionTime() documentation states:

Returns the approximate accumulated collection elapsed time in milliseconds. This method returns -1 if the collection elapsed time is undefined for this collector.

The Java virtual machine implementation may use a high resolution timer to measure the elapsed time. This method may return the same value even if the collection count has been incremented if the collection elapsed time is very short.

Which is what the test tested

Testing: test does not fail any more after some VM hack so that getCollectionTime() returns very low values.

Thanks,
Thomas

---

Progress

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Issue

• JDK-8268906: gc/g1/mixedgc/TestOldGenCollectionUsage.java assumes that GCs take 1ms minimum

Reviewers

• Kim Barrett (@kimbarrett - Reviewer)
• Albert Mingkun Yang (@albertnetymk - Committer)
• Leo Korinth (@lkorinth - Committer)

Reviewing

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[bridgekeeper]

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (5c96893e)

[kimbarrett]

Looks good.

[openjdk]

@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:

8268906: gc/g1/mixedgc/TestOldGenCollectionUsage.java assumes that GCs take 1ms minimum

Reviewed-by: kbarrett, ayang, lkorinth

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At the time when this comment was updated there had been 153 new commits pushed to the master branch:

• ee0247f: 8263461: jdk/jfr/event/gc/detailed/TestEvacuationFailedEvent.java uses wrong mechanism to cause evacuation failure
• 3ad20fc: 8269571: NMT should print total malloc bytes and invocation count
• b969136: 8245877: assert(_value != __null) failed: resolving NULL _value in JvmtiExport::post_compiled_method_load
• ee526a2: Merge
• 0d745ae: 8269034: AccessControlException for SunPKCS11 daemon threads
• d042029: 8269529: javax/swing/reliability/HangDuringStaticInitialization.java fails in Windows debug build
• 401cb0a: 8269232: assert(!is_jweak(handle)) failed: wrong method for detroying jweak
• b8a16e9: 8268884: C2: Compile::remove_speculative_types must iterate top-down
• 25f9f19: 8249646: Runtime.exec(String, String[], File) documentation contains literal {@link ...}
• 0d83dc2: 8268699: Shenandoah: Add test for JDK-8268127
• ... and 143 more: https://git.openjdk.java.net/jdk/compare/5ae9a12858a20361c163e1dfe6b67970f27e4e40...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]

Thanks @kimbarrett for your review.

[lkorinth]

Looks good to me.

[tschatzl]

Thanks @kimbarrett @lkorinth @albertnetymk for your reviews.

/integrate

[openjdk]

Going to push as commit a0f32cb.
Since your change was applied there have been 153 commits pushed to the master branch:

• ee0247f: 8263461: jdk/jfr/event/gc/detailed/TestEvacuationFailedEvent.java uses wrong mechanism to cause evacuation failure
• 3ad20fc: 8269571: NMT should print total malloc bytes and invocation count
• b969136: 8245877: assert(_value != __null) failed: resolving NULL _value in JvmtiExport::post_compiled_method_load
• ee526a2: Merge
• 0d745ae: 8269034: AccessControlException for SunPKCS11 daemon threads
• d042029: 8269529: javax/swing/reliability/HangDuringStaticInitialization.java fails in Windows debug build
• 401cb0a: 8269232: assert(!is_jweak(handle)) failed: wrong method for detroying jweak
• b8a16e9: 8268884: C2: Compile::remove_speculative_types must iterate top-down
• 25f9f19: 8249646: Runtime.exec(String, String[], File) documentation contains literal {@link ...}
• 0d83dc2: 8268699: Shenandoah: Add test for JDK-8268127
• ... and 143 more: https://git.openjdk.java.net/jdk/compare/5ae9a12858a20361c163e1dfe6b67970f27e4e40...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit a0f32cb.

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