8304996: Add missing HandleMarks #13215

dholmes-ora · 2023-03-28T20:51:46Z

The review for JDK-8304147 pointed out that the top-level HandleMark in dump_for_exit (added to replace the previous coverage from a HandleMarkCleaner in JVM_ENTRY) was not in the right place as no Handles were being used there. Removing that HM and fixing up the ensuing failures led to a set of fixes where HM's were missing at the place of Handle usage.

Testing: tiers 1-4

Thanks.

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Issue

JDK-8304996: Add missing HandleMarks

Reviewers

Coleen Phillimore (@coleenp - Reviewer) ⚠️ Review applies to 0ffe0f20
Aleksey Shipilev (@shipilev - Reviewer)
Ioi Lam (@iklam - Reviewer)

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$ git pull https://git.openjdk.org/jdk.git pull/13215/head

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bridgekeeper · 2023-03-28T20:52:59Z

👋 Welcome back dholmes! 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 · 2023-03-28T20:55:23Z

@dholmes-ora The following label will be automatically applied to this pull request:

hotspot

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dholmes-ora · 2023-03-28T21:20:27Z

/label add hotspot-runtime
/label remove hotspot

openjdk · 2023-03-28T21:21:38Z

@dholmes-ora
The hotspot-runtime label was successfully added.

openjdk · 2023-03-28T21:22:46Z

@dholmes-ora
The hotspot label was successfully removed.

mlbridge · 2023-03-28T22:11:28Z

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01: Full - Incremental (f6ed1926)
00: Full (0ffe0f20)

coleenp

Looks good! thank you for fixing these.

openjdk · 2023-03-28T22:46:16Z

@dholmes-ora 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:

8304996: Add missing HandleMarks

Reviewed-by: coleenp, shade, iklam

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 91 new commits pushed to the master branch:

b062b1b: 8304743: Compile_lock and SystemDictionary updates
df819cf: 8304945: StringBuilder and StringBuffer should implement Appendable explicitly
312bbe7: 8305485: Problemlist runtime/Thread/TestAlwaysPreTouchStacks.java
50e31e0: 8305442: (bf) Direct and view implementations of CharBuffer.toString(int, int) do not need to catch SIOBE
85e3974: 8304014: Convert test/jdk/java/util/zip/ZipFile/CorruptedZipFiles.java to junit
40aea04: 8278268: (ch) InputStream returned by Channels.newInputStream should have fast path for FileChannel targets
9b9b5a7: 8302323: Add repeat methods to StringBuilder/StringBuffer
dd7ca75: 8305478: [REDO] disable gtest/NMTGtests.java sub-tests failing due to JDK-8305414
f9827ad: 8288109: HttpExchangeImpl.setAttribute does not allow null value after JDK-8266897
6010de0: 8305417: disable gtest/NMTGtests.java sub-tests failing due to JDK-8305414
... and 81 more: https://git.openjdk.org/jdk/compare/6aec6f3a842ead30b26cd31dc57a2ab268f67875...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.

dholmes-ora · 2023-03-28T23:51:14Z

Thanks @coleenp !

shipilev

I think the issue synopsis should be capitalized: "Add missing HandleMarks". Also, does it cover the cases that were not covered by dump_at_exit HandleMark before? If not, then it is not adding "missing" HMs.

shipilev · 2023-03-29T08:37:39Z

src/hotspot/share/oops/klassVtable.cpp

@@ -1174,6 +1175,7 @@ void klassItable::initialize_itable(GrowableArray<Method*>* supers) {
 void klassItable::check_constraints(GrowableArray<Method*>* supers, TRAPS) {

  assert(_size_method_table == supers->length(), "wrong size");
+  HandleMark hm(THREAD);


Question: Would this make the handles area grow up to _size_method_table in the worst case? I thought we want to have HandleMark-s closer to actual handle creation/last-use to keep the footprint at bay.

I was optimising for runtime performance rather than footprint, but you are right this could grow in a way we don't want. So I reverted this change and made a similar change to klassVtable::check_constraints.

Thanks for looking at this @shipilev .

dholmes-ora · 2023-03-29T21:37:24Z

I think the issue synopsis should be capitalized: "Add missing HandleMarks". Also, does it cover the cases that were not covered by dump_at_exit HandleMark before? If not, then it is not adding "missing" HMs.

Fixed capitalization in HandleMark.

Not sure what your issue is with "missing" - the HM's were not present where the Handles were used and hence were missing. Some cases were directly detected by removing the old HM in dump_for_exit but I also checked those files for other cases and added them.

iklam · 2023-03-30T00:46:08Z

What are the rules for using HandleMarks? In the HotSpot code, there are plenty of cases where we create a HandleMark without creating any Handles in the immediately following code. There are also plenty of cases where Handles are created in functions that do not have any HandleMarks.

dholmes-ora · 2023-03-30T01:12:02Z

What are the rules for using HandleMarks? In the HotSpot code, there are plenty of cases where we create a HandleMark without creating any Handles in the immediately following code. There are also plenty of cases where Handles are created in functions that do not have any HandleMarks.

@coleenp has a lot to say on this but basically HM's should appear along-side the code that creates the Handles. Unless you return a Handle from a function, there should generally be a HM in the function. There is a lot of code that doesn't follow this. Partly I think this is because we have some high-on-the-stack HMs or HandleMarkCleaners that hide the creation of Handles without a local HandleMark. Conversely if new code uses existing code that doesn't have a HM and gets an error, then the typical response is to put a HM in the new code - especially because that only affects the new change, whereas putting a HM lower-down could be seen as disruptive etc.

shipilev

Looks fine to me. (I'd probably put HandleMark after the comment, closer to the code in check_constraints, but no need to do that if there are no other changes pending.)

shipilev · 2023-03-30T07:53:25Z

Not sure what your issue is with "missing" - the HM's were not present where the Handles were used and hence were missing. Some cases were directly detected by removing the old HM in dump_for_exit but I also checked those files for other cases and added them.

When I read a synopsis "Add missing HMs", that means to me there are code paths that allocate Handles without HMs -- meaning there is a memory leak. If we just dropped an "umbrella" HM in dump_for_exit and only added the HMs that were needed after that removal, that just rebalances the ways we cut and slice the HMs, and that does not affect memory leaks. This distinction is important to gauge how serious the issue is, and whether it should be backported, for example. This is why I wanted to understand the meaning of "missing" here :)

dholmes-ora · 2023-03-30T07:53:25Z

Thanks @shipilev !

dholmes-ora · 2023-04-02T23:22:48Z

Any other comments? @iklam or @coleenp ?

iklam

LGTM

dholmes-ora · 2023-04-04T02:03:46Z

Thanks @iklam !

/integrate

openjdk · 2023-04-04T02:04:54Z

Going to push as commit a7546b3.
Since your change was applied there have been 96 commits pushed to the master branch:

ac898e9: 8303278: Imprecise bottom type of ExtractB/UB
a1a9ec6: 8297286: runtime/vthread tests crashing after JDK-8296324
c6bd489: 8305206: Add @SPEC tags in java.base/java.* (part 1)
ccbb0e8: 8303798: REDO - Remove fdlibm C sources
9ce5fdc: 8305421: Work around JDK-8305420 in CDSJDITest.java
b062b1b: 8304743: Compile_lock and SystemDictionary updates
df819cf: 8304945: StringBuilder and StringBuffer should implement Appendable explicitly
312bbe7: 8305485: Problemlist runtime/Thread/TestAlwaysPreTouchStacks.java
50e31e0: 8305442: (bf) Direct and view implementations of CharBuffer.toString(int, int) do not need to catch SIOBE
85e3974: 8304014: Convert test/jdk/java/util/zip/ZipFile/CorruptedZipFiles.java to junit
... and 86 more: https://git.openjdk.org/jdk/compare/6aec6f3a842ead30b26cd31dc57a2ab268f67875...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-04-04T02:05:08Z

@dholmes-ora Pushed as commit a7546b3.

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

Fix up HandleMarks

0ffe0f2

openjdk bot added the hotspot hotspot-dev@openjdk.org label Mar 28, 2023

openjdk bot added the hotspot-runtime hotspot-runtime-dev@openjdk.org label Mar 28, 2023

openjdk bot removed the hotspot hotspot-dev@openjdk.org label Mar 28, 2023

dholmes-ora changed the title ~~Fix up HandleMarks~~ 8304996: Add missing Handlemarks Mar 28, 2023

openjdk bot changed the title ~~8304996: Add missing Handlemarks~~ 8304996: Add missing Handlemarks Mar 28, 2023

dholmes-ora marked this pull request as ready for review March 28, 2023 22:05

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coleenp approved these changes Mar 28, 2023

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dholmes-ora changed the title ~~8304996: Add missing Handlemarks~~ 8304996: Add missing HandleMarks Mar 29, 2023

Shipilev feedback - moved HMs back inside the loops.

f6ed192

dholmes-ora requested a review from shipilev March 29, 2023 22:06

shipilev approved these changes Mar 30, 2023

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iklam approved these changes Apr 3, 2023

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dholmes-ora deleted the handlemark branch April 4, 2023 02:33

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8304996: Add missing HandleMarks #13215

8304996: Add missing HandleMarks #13215

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8304996: Add missing HandleMarks #13215

8304996: Add missing HandleMarks #13215

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