The following test fails in the JDK21 CI:

com/sun/jdi/JdbStopThreadTest.java

Here's a log file snippet from the linux-x64-open sighting:

#section:main
----------messages:(7/295)----------
command: main JdbStopThreadTest
reason: User specified action: run main/othervm JdbStopThreadTest
started: Wed Feb 01 21:12:21 UTC 2023
Mode: othervm [/othervm specified]
Additional options from @modules: --add-modules jdk.jdi
finished: Wed Feb 01 21:12:27 UTC 2023
elapsed time (seconds): 6.2
----------configuration:(3/35)----------
Boot Layer
  add modules: jdk.jdi

----------System.out:(35/4189)*----------
Command line: [/opt/mach5/mesos/work_dir/jib-master/install/jdk-21+8-582/linux-x64-open.jdk/jdk-21/bin/java -cp /opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S8394/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/363e5923-f286-4c4a-a92f-1c4e44d12054/runs/5de04201-bcd1-4619-bd6f-ca750be7c170/testoutput/test-support/jtreg_open_test_jdk_tier3/classes/1/com/sun/jdi/JdbStopThreadTest.d:/opt/mach5/mesos/work_dir/jib-master/install/jdk-21+8-582/src.full/open/test/jdk/com/sun/jdi:/opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S8394/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/363e5923-f286-4c4a-a92f-1c4e44d12054/runs/5de04201-bcd1-4619-bd6f-ca750be7c170/testoutput/test-support/jtreg_open_test_jdk_tier3/classes/1/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jdk-21+8-582/src.full/open/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/7.1.1/1/bundles/jtreg-7.1.1+1.zip/jtreg/lib/jtreg.jar -Xmx768m -XX:MaxRAMPercentage=4.16667 -Dtest.boot.jdk=/opt/mach5/mesos/work_dir/jib-master/install/jdk/19/36/bundles/linux-x64/jdk-19_linux-x64_bin.tar.gz/jdk-19 -Djava.io.tmpdir=/opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S8394/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/363e5923-f286-4c4a-a92f-1c4e44d12054/runs/5de04201-bcd1-4619-bd6f-ca750be7c170/testoutput/test-support/jtreg_open_test_jdk_tier3/tmp -ea -esa -agentlib:jdwp=transport=dt_socket,server=y,suspend=y JdbStopThreadTestTarg ]
[debuggee]:/opt/mach5/mesos/work_dir/jib-master/install/jdk-21+8-582/linux-x64-open.jdk/jdk-21/bin/java -cp /opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S8394/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/363e5923-f286-4c4a-a92f-1c4e44d12054/runs/5de04201-bcd1-4619-bd6f-ca750be7c170/testoutput/test-support/jtreg_open_test_jdk_tier3/classes/1/com/sun/jdi/JdbStopThreadTest.d:/opt/mach5/mesos/work_dir/jib-master/install/jdk-21+8-582/src.full/open/test/jdk/com/sun/jdi:/opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S8394/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/363e5923-f286-4c4a-a92f-1c4e44d12054/runs/5de04201-bcd1-4619-bd6f-ca750be7c170/testoutput/test-support/jtreg_open_test_jdk_tier3/classes/1/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jdk-21+8-582/src.full/open/test/lib:/opt/mach5/mesos/work_dir/jib-master/install/jtreg/7.1.1/1/bundles/jtreg-7.1.1+1.zip/jtreg/lib/jtreg.jar -Xmx768m -XX:MaxRAMPercentage=4.16667 -Dtest.boot.jdk=/opt/mach5/mesos/work_dir/jib-master/install/jdk/19/36/bundles/linux-x64/jdk-19_linux-x64_bin.tar.gz/jdk-19 -Djava.io.tmpdir=/opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S8394/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/363e5923-f286-4c4a-a92f-1c4e44d12054/runs/5de04201-bcd1-4619-bd6f-ca750be7c170/testoutput/test-support/jtreg_open_test_jdk_tier3/tmp -ea -esa -agentlib:jdwp=transport=dt_socket,server=y,suspend=y JdbStopThreadTestTarg
[debuggee] Listening for transport dt_socket at address: 38269
[jdb] Set uncaught java.lang.Throwable
[jdb] Set deferred uncaught java.lang.Throwable
[jdb] Initializing jdb ...
[jdb]
[jdb] VM Started: > No frames on the current call stack
[jdb]
[jdb] main[1]
> stop thread at JdbStopThreadTestTarg:46
[jdb] Deferring breakpoint JdbStopThreadTestTarg:46.
[jdb] It will be set after the class is loaded.
[jdb] main[1]
> run
[jdb] > Set deferred breakpoint JdbStopThreadTestTarg:46
[jdb]
[jdb] Breakpoint hit: "thread=main", JdbStopThreadTestTarg.test(), line=46 bci=4
[jdb] 46 print(thread); // @1 breakpoint
[jdb] >
> thread 1
[jdb] main[1]
> stop go at JdbStopThreadTestTarg:48
[jdb] Set breakpoint JdbStopThreadTestTarg:48
[jdb] main[1]
> cont
[debuggee] Thread[#1,main,5,main]
[debuggee] test
[jdb] >
[jdb] Breakpoint hit:
[jdb] The application exited
[jdb]
=======================================
Exception thrown during test execution: '^Breakpoint hit: "thread=main", JdbStopThreadTestTarg\\.test\\(\\), line=48.*\\R48\\s+print\\(str\\);.*\\R>\\s' missing from stdout/stderr
=======================================
----------System.err:(60/2263)*----------
 stdout: [Set uncaught java.lang.Throwable
Set deferred uncaught java.lang.Throwable
Initializing jdb ...

VM Started: > No frames on the current call stack

main[1]
Deferring breakpoint JdbStopThreadTestTarg:46.
It will be set after the class is loaded.
main[1]
> Set deferred breakpoint JdbStopThreadTestTarg:46

Breakpoint hit: "thread=main", JdbStopThreadTestTarg.test(), line=46 bci=4
46 print(thread); // @1 breakpoint
>
main[1]
Set breakpoint JdbStopThreadTestTarg:48
main[1]
>
Breakpoint hit:
The application exited
];
 stderr: [Set uncaught java.lang.Throwable
Set deferred uncaught java.lang.Throwable
Initializing jdb ...

VM Started: > No frames on the current call stack

main[1]
Deferring breakpoint JdbStopThreadTestTarg:46.
It will be set after the class is loaded.
main[1]
> Set deferred breakpoint JdbStopThreadTestTarg:46

Breakpoint hit: "thread=main", JdbStopThreadTestTarg.test(), line=46 bci=4
46 print(thread); // @1 breakpoint
>
main[1]
Set breakpoint JdbStopThreadTestTarg:48
main[1]
>
Breakpoint hit:
The application exited
]
 exitValue = -1

java.lang.RuntimeException: '^Breakpoint hit: "thread=main", JdbStopThreadTestTarg\\.test\\(\\), line=48.*\\R48\\s+print\\(str\\);.*\\R>\\s' missing from stdout/stderr
at jdk.test.lib.process.OutputAnalyzer.shouldMatch(OutputAnalyzer.java:340)
at JdbStopThreadTest.runCases(JdbStopThreadTest.java:88)
at lib.jdb.JdbTest.run(JdbTest.java:96)
at JdbStopThreadTest.main(JdbStopThreadTest.java:58)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:578)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:125)
at java.base/java.lang.Thread.run(Thread.java:1623)

JavaTest Message: Test threw exception: java.lang.RuntimeException: '^Breakpoint hit: "thread=main", JdbStopThreadTestTarg\\.test\\(\\), line=48.*\\R48\\s+print\\(str\\);.*\\R>\\s' missing from stdout/stderr
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.RuntimeException: '^Breakpoint hit: "thread=main", JdbStopThreadTestTarg\\.test\\(\\), line=48.*\\R48\\s+print\\(str\\);.*\\R>\\s' missing from stdout/stderr
----------rerun:(38/6688)*----------