8294370: Fix allocation bug in java_lang_Thread::async_get_stack_trace() #10424

pchilano · 2022-09-26T14:23:38Z

Please review this small fix in async_get_stack_trace(). The GrowableArrays created to store the bci and Method* of each frame found while traversing the stack are allocated in the resource area of the thread that calls async_get_stack_trace(). But if the handshake is executed by the target and if the number of frames in the stack exceeds the initial size of the GrowableArrays then we will hit an assertion when trying to grow the size of the arrays (see bug description).
Currently we don't see any issues because the initial size of the GrowableArrays is 512 and our tests don't test beyond that (the maximum value of DEPTH in the vmTestbase/nsk/stress/strace/ tests is 500). The issue can be easily reproduced by either decreasing the initial size of the GrowableArrays or by increasing the value of DEPTH in those strace tests.
To fix it I allocated the arrays in the C heap instead. Also I lowered the initial size of the arrays since 512 seemed too much to start with.
Tested it by running all tests in the vmTestbase/nsk/stress/strace/ directory.

Thanks,
Patricio

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Issue

JDK-8294370: Fix allocation bug in java_lang_Thread::async_get_stack_trace()

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David Holmes (@dholmes-ora - Reviewer) ⚠️ Review applies to 5e375a83
Serguei Spitsyn (@sspitsyn - Reviewer) ⚠️ Review applies to 5e375a83

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bridgekeeper · 2022-09-26T14:24:21Z

👋 Welcome back pchilanomate! 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 · 2022-09-26T14:26:56Z

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

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openjdk · 2022-09-26T14:29:49Z

@pchilano
The label hotspot-serviceability is not a valid label.
These labels are valid:

serviceability
hotspot
hotspot-compiler
ide-support
kulla
i18n
shenandoah
jdk
javadoc
security
hotspot-runtime
jmx
build
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client
core-libs
compiler
net
hotspot-gc
hotspot-jfr

pchilano · 2022-09-26T14:35:10Z

/label add serviceability

openjdk · 2022-09-26T14:36:41Z

@pchilano
The serviceability label was successfully added.

mlbridge · 2022-09-26T15:40:55Z

Webrevs

01: Full - Incremental (68486d1a)
00: Full (5e375a83)

dholmes-ora

Good find! Looks good! A couple of queries at this stage.

Thanks.

dholmes-ora · 2022-09-27T06:39:37Z

src/hotspot/share/classfile/javaClasses.cpp

@@ -2000,6 +2001,11 @@ oop java_lang_Thread::async_get_stack_trace(oop java_thread, TRAPS) {
      const int max_depth = MaxJavaStackTraceDepth;
      const bool skip_hidden = !ShowHiddenFrames;

+      // Pick some initial length


The comment should at least hint at there being some reasonable reason for choosing the value that follows. :)

How about: "Pick minimum length that will cover most cases"?

Sounds good.

dholmes-ora · 2022-09-27T06:42:39Z

src/hotspot/share/classfile/javaClasses.cpp

+      int init_length = 64;
+      _methods = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<Method*>(init_length, mtInternal);
+      _bcis = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(init_length, mtInternal);
+


Couldn't you just do this in the constructor? I'm not clear if there is a subtle reason for needing lazy-init as well as moving to the C_Heap.

Yes, this could have been done in the constructor too. But since there are additional checks in the closure that could fail I move the allocation here to avoid unnecessary allocation/deallocation. The allocation still needs to be done in the C_Heap in case the target executes the handshake. Otherwise if the target allocates the arrays in its resource area they could be deallocated by the time the requester tries to access them after the handshake.

Good point - only allocate when known to be needed.

pchilano · 2022-09-27T16:09:00Z

Good find! Looks good! A couple of queries at this stage.

Thanks.

Thanks for looking at this David.

dholmes-ora

Looks good.

Thanks

dholmes-ora · 2022-09-28T01:53:46Z

src/hotspot/share/classfile/javaClasses.cpp

@@ -2000,6 +2001,11 @@ oop java_lang_Thread::async_get_stack_trace(oop java_thread, TRAPS) {
      const int max_depth = MaxJavaStackTraceDepth;
      const bool skip_hidden = !ShowHiddenFrames;

+      // Pick some initial length


Sounds good.

dholmes-ora · 2022-09-28T01:54:57Z

src/hotspot/share/classfile/javaClasses.cpp

+      int init_length = 64;
+      _methods = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<Method*>(init_length, mtInternal);
+      _bcis = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<int>(init_length, mtInternal);
+


Good point - only allocate when known to be needed.

openjdk · 2022-09-28T01:56:15Z

@pchilano 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:

8294370: Fix allocation bug in java_lang_Thread::async_get_stack_trace()

Reviewed-by: dholmes, sspitsyn

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 45 new commits pushed to the master branch:

70d8428: 8294520: Problemlist java/nio/file/Files/CopyProcFile.java
30e3bf9: 8291805: IGV: Improve Zooming
37f83b9: 8294375: test/jdk/java/nio/channels/vthread/BlockingChannelOps.java is slow
60616f2: 8294059: Serial: Refactor GenCollectedHeap::collect
ea61671: 8294359: Interpreter(AArch64) intrinsify Thread.currentThread()
c42ef70: 7148092: [macosx] When Alt+down arrow key is pressed, the combobox popup does not appear.
94e14da: 8294057: Parallel: Tighten ParallelCompactData::initialize_region_data
1ea0d6b: 8292301: [REDO v2] C2 crash when allocating array of size too large
c13e0ef: 8292848: AWT_Mixing and TrayIcon tests fail on el8 with hard-coded isOel7
79ccc79: 8293613: need to properly handle and hide tmp VTMS transitions
... and 35 more: https://git.openjdk.org/jdk/compare/3675f4c2afd10b5042948fc79e62caee5f3874ce...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.

sspitsyn

Yes, it is good find!
The fix looks good.
Thanks,
Serguei

pchilano · 2022-09-28T14:44:05Z

Thanks for the reviews David and Serguei!

pchilano · 2022-09-29T15:33:50Z

/integrate

openjdk · 2022-09-29T15:35:52Z

Going to push as commit 5d48da4.
Since your change was applied there have been 57 commits pushed to the master branch:

ce85cac: 8065554: MatchResult should provide values of named-capturing groups
1decdce: 8294492: RISC-V: Use li instead of patchable movptr at non-patchable callsites
8491fd5: 8294551: Put java/io/BufferedInputStream/TransferTo.java on problem list
6f8f28e: 8294160: misc crash dump improvements
8873192: 8293515: heapShared.cpp: rename JavaThread parameter to current
76f1865: 8293563: [macos-aarch64] SA core file tests failing with sun.jvm.hotspot.oops.UnknownOopException
9db95ed: 8215788: Clarify JarInputStream Manifest access
9309786: 8294472: Remove redundant rawtypes suppression in AbstractChronology
3b7fc80: 8294411: SA should provide more useful info when it fails to start up due to "failed to workaround classshareing"
4fb424b: 8293961: Unused ClassPathZipEntry::contents_do
... and 47 more: https://git.openjdk.org/jdk/compare/3675f4c2afd10b5042948fc79e62caee5f3874ce...master

Your commit was automatically rebased without conflicts.

openjdk · 2022-09-29T15:36:16Z

@pchilano Pushed as commit 5d48da4.

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

v1

5e375a8

openjdk bot added the hotspot-runtime hotspot-runtime-dev@openjdk.org label Sep 26, 2022

openjdk bot added the serviceability serviceability-dev@openjdk.org label Sep 26, 2022

pchilano marked this pull request as ready for review September 26, 2022 15:35

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8294370: Fix allocation bug in java_lang_Thread::async_get_stack_trace() #10424

8294370: Fix allocation bug in java_lang_Thread::async_get_stack_trace() #10424

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8294370: Fix allocation bug in java_lang_Thread::async_get_stack_trace() #10424

8294370: Fix allocation bug in java_lang_Thread::async_get_stack_trace() #10424

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pchilano commented Sep 26, 2022 • edited by openjdk bot

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