8390661: gc/TestGCALotAtSafepoints sub-tests times out

[tschatzl]

Hi all,

the tests in JDK-8389096 discovered more hangs with . There were two main causes:

• the place where the previous place allowed GC after logical release of a monitor but before releasing the OS monitor in some cases is too weak, there are a few potential cases where a deadlock could happen due to indirect monitor uses. The solution is to just conservatively disable GC-alot GCs in this situation.
• shutdown in particular had the issue where trying to do a GC-alot GC while we are shutting down would hang. One example is that Universe::before_exit() shuts down the GC, then other threads go into ::before_exit(). These threads trying to get - but the GC VM operation blocks if shutting down, so the VM will hang there.

The CI hangs were of the second sort. They were also confusing because jtreg reported that the test completed during timeout handling.

Testing: running the now un-problemlisted tests again for many times, no failure.

Hth,
Thomas

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Issue

• JDK-8390661: gc/TestGCALotAtSafepoints sub-tests times out (Bug - P4)

Reviewers

• Axel Boldt-Christmas (@xmas92 - Reviewer)
• Coleen Phillimore (@coleenp - Reviewer)
• Albert Mingkun Yang (@albertnetymk - Reviewer)

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8390661: gc/TestGCALotAtSafepoints sub-tests times out

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At the time when this comment was updated there had been 115 new commits pushed to the master branch:

• 7353d17: 8388288: RISC-V: Use Zicond instruction for encode/decode heap oop
• ee2ebf6: 8386092: Implement JEP 541: Deprecate the macOS/x64 Port for Removal
• cf02393: 8388795: Add --app-resources CLI option to copy files and directories into the application resources directory
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[tschatzl]

/label add hotspot-gc

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@tschatzl
The hotspot-gc label was successfully added.

[tschatzl]

As mentioned in another comment, we need to reduce the amount of GCs using -XX:ScavengeALotInterval for all configurations. Depending on the test setup it could otherwise cause timeouts due to running an excessively amount of gcs.

Tested with around ~7000 runs of the test, with no failure any more.

[xmas92]

lgtm. Thanks for fixing.

[coleenp]

This looks good.

[tschatzl]

Thanks @coleenp @albertnetymk @xmas92 for your reviews

/integrate

[openjdk]

Going to push as commit 31f4e43.
Since your change was applied there have been 122 commits pushed to the master branch:

• 1d173df: 8391174: Simplify identity_hash after UseObjectMonitorTable removal
• d398b22: 8391178: TypeAryPtr::narrow_size_type returns incorrect type for flat arrays
• 66c21ae: 8391171: Enable TestVectorBroadcastTransforms.java IR tests for RISC-V
• ... and 119 more: https://git.openjdk.org/jdk/compare/7bc01544236d8e6e2d3d0b9d72e4c9e736b57c62...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit 31f4e43.

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