jmx-dev RFR: 8360599: [TESTBUG] DumpThreadsWithEliminatedLock.java fails because of unstable inlining [v2]

[Alan Bateman]

On Fri, 4 Jul 2025 08:14:19 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

>> This PR adds CompileCommands to the test DumpThreadsWithEliminatedLock.java to force inlining of java/lang/String*.* methods. This will make inlining more stable to allow for the expected lock elimination based on c2 escape analysis.
>> 
>> Forcing inlining of java/lang/StringBuffer.* wasn't sufficient on x86_64. With that the test still failed with TieredCompilation disabled.
>> 
>> Testing: x86_64, ppc64 manually. Other major platforms as part of our CI testing.
>> 
>> Failed inlining on x86_64 with TieredCompilation disabled:
>> 
>> 
>> make test TEST=com/sun/management/HotSpotDiagnosticMXBean/DumpThreadsWithEliminatedLock.java TEST_VM_OPTS="-XX:-TieredCompilation -XX:+UnlockDiagnosticVMOptions -XX:CompileCommand=PrintInlining,DumpThreadsWithEliminatedLock.*" JTREG=TIMEOUT_FACTOR=0.1
>> 
>> [...]
>> 
>> STDOUT:
>> CompileCommand: PrintInlining DumpThreadsWithEliminatedLock.* bool PrintInlining = true
>>                             @ 1   java.util.concurrent.atomic.AtomicBoolean::get (13 bytes)   inline (hot)
>>                             @ 11   java.lang.StringBuffer::<init> (7 bytes)   inline (hot)   late inline succeeded (string method)
>>                               @ 3   java.lang.AbstractStringBuilder::<init> (39 bytes)   inline (hot)
>>                                 @ 1   java.lang.Object::<init> (1 bytes)   inline (hot)
>>                             @ 16   java.lang.System::currentTimeMillis (0 bytes)   (intrinsic)
>>               s             @ 19   java.lang.StringBuffer::append (13 bytes)   failed to inline: already compiled into a big method
>>               s             @ 24   java.lang.StringBuffer::toString (44 bytes)   inline (hot)   late inline succeeded (string method)
>>               s               @ 1   java.lang.StringBuffer::length (5 bytes)   accessor
>>                               @ 24   java.lang.String::<init> (98 bytes)   failed to inline: already compiled into a big method
>>                             @ 30   java.util.concurrent.atomic.AtomicReference::set (6 bytes)   accessor
>> 2025-07-02T09:25:53.396634900Z Attempt 1, found: false
>> 2025-07-02T09:25:53.415673072Z Attempt 2, found: false
>> 2025-07-02T09:25:53.418876867Z Attempt 3, found: false
>> 
>> [...]
>
> Richard Reingruber has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Allow vm.debug

Marked as reviewed by alanb (Reviewer).

-------------

PR Review: https://git.openjdk.org/jdk/pull/26033#pullrequestreview-2986518539