8279662: serviceability/sa/ClhsdbScanOops.java can fail do to unexpected GC

[plummercj]

The test is failing to find certain types in the scanoops output when run with -Xcomp. This is happening in the loom repo. The reason it is happening there is because loom introduced a full GC during codecache sweeping. The test only runs scanoops on the eden gen, and the full GC is causing objects of certain expected types to no longer be present in the eden gen. The fix is to also check the old gen.

The logic of the test had to be reworked a bit to accomplish checking the output of two scanoops commands together. It was relying on the ClhsdbLauncher class to check the output for expected strings, but in this case we need to accumulate the output of the two scanoops commands and check the combined output for the expected strings, so now the checking is done directly by the test and not by ClhsdbLauncher.

I'm choosing to fix this in the jdk repo rather than the loom repo since it is a latent bug that theoretically could occur even without the loom changes, and also to help reduce the amount of changes to be reviewed when loom is integrated into jdk.

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Issue

• JDK-8279662: serviceability/sa/ClhsdbScanOops.java can fail do to unexpected GC

Reviewers

• Serguei Spitsyn (@sspitsyn - Reviewer)
• Kevin Walls (@kevinjwalls - Committer)

Reviewing

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (20d3a7d0)

[sspitsyn]

Looks reasonable to me.
There is minor duplication but it is okay as there is no good way to get rid of it.
Thanks,
Serguei

[openjdk]

@plummercj This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8279662: serviceability/sa/ClhsdbScanOops.java can fail do to unexpected GC

Reviewed-by: sspitsyn, kevinw

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At the time when this comment was updated there had been 221 new commits pushed to the master branch:

• de826ba: 8280600: C2: assert(!had_error) failed: bad dominance
• 4304a77: 8279535: C2: Dead code in PhaseIdealLoop::create_loop_nest after JDK-8276116
• ab63834: 8280885: Shenandoah: Some tests failed with "EA: missing allocation reference path"
• 48a32b5: 8280976: Incorrect encoding of avx512 vpsraq instruction with mask and constant shift.
• 97af323: 8280842: Access violation in ciTypeFlow::profiled_count
• d32f99e: 8279219: [REDO] C2 crash when allocating array of size too large
• 85d839f: 8280601: ClhsdbThreadContext.java test is triggering codecache related asserts
• 9ca7ff3: 8281082: Improve javadoc references to JOSS
• c74b8f4: 8275914: SHA3: changing java implementation to help C2 create high-performance code
• a18beb4: 8280867: Cpuid1Ecx feature parsing is incorrect for AMD CPUs
• ... and 211 more: https://git.openjdk.java.net/jdk/compare/46fd683820bb7149c0605a0ba03f59e76de69c16...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.

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[plummercj]

There is minor duplication but it is okay as there is no good way to get rid of it.

I considered a loop or common method, but it seemed not to be worth it and likely less readable.

[sspitsyn]

Agreed.

[kevinjwalls]

Looks good.
For the scanoops for a type, it seems like a reasonable assumption that there will be a String in the old gen!

[plummercj]

For the scanoops for a type, it seems like a reasonable assumption that there will be a String in the old gen!

Actually it's not, and that's why I check the Eden gen. If a GC is not triggered, the old gen will be empty. It not actually guaranteed that a String will be in the Eden gen either, but at least at the moment that appears to be the case whether or not a GC is triggered.

[kevinjwalls]

Actually it's not, and that's why I check the Eden gen.

Yes sorry, should have said it's a good bet to find a String when only checking one generation. Carry on...

[plummercj]

/integrate

[openjdk]

Going to push as commit fe0118f.
Since your change was applied there have been 228 commits pushed to the master branch:

• e3d5c9e: 8266974: duplicate property key in java.sql.rowset resource bundle
• 47800bf: 8280868: LineBodyHandlerTest.java creates and discards too many clients
• 9d57853: 8281042: G1: Remove unused init_threshold in G1FullGCCompactionPoint
• 87ab099: 8280944: Enable Unix domain sockets in Windows Selector notification mechanism
• ce71e8b: 8279917: Refactor subclassAudits in Thread to use ClassValue
• 4ea6037: 8281035: Serial: Move RemoveForwardedPointerClosure to local scope
• ae2504b: 8278254: Cleanup doclint warnings in java.desktop module
• de826ba: 8280600: C2: assert(!had_error) failed: bad dominance
• 4304a77: 8279535: C2: Dead code in PhaseIdealLoop::create_loop_nest after JDK-8276116
• ab63834: 8280885: Shenandoah: Some tests failed with "EA: missing allocation reference path"
• ... and 218 more: https://git.openjdk.java.net/jdk/compare/46fd683820bb7149c0605a0ba03f59e76de69c16...master

Your commit was automatically rebased without conflicts.

[openjdk]

@plummercj Pushed as commit fe0118f.

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