The following test failed in the JDK15 CI:

serviceability/sa/TestClhsdbJstackLock.java

Here's a snippet from the failing log:

"Thread-0" #13 prio=5 tid=0x00007fc65c5e2800 nid=0x706b waiting on condition [0x00007fc6209a3000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
   JavaThread state: _thread_blocked
 - java.lang.Thread.sleep(long) @bci=0 (Interpreted frame)
 - LingeredAppWithLock.lockMethod(java.lang.Object) @bci=7, line=32 (Interpreted frame)
- locked <0x++++ Eliminated: 1479 Allocate
000000048f454230> ++++ Eliminated: 1321 Allocate
(a java.lang.Class for LingeredAppWithLock)
 - LingeredAppWithLock.lambda$main$0() @bci=2, line=40 (Interpreted frame)
 - LingeredAppWithLock$$Lambda$1.run() @bci=0 (Interpreted frame)
 - java.lang.Thread.run() @bci=11, line=832 (Interpreted frame)

Locked ownable synchronizers:
    - None

<snip>

]
 exitValue = -1

 LingeredApp stdout: [];
 LingeredApp stderr: []
 LingeredApp exitValue = 0
java.lang.RuntimeException: Test ERROR java.lang.RuntimeException: '^\\s+- locked <0x[0-9a-f]+> \\(a java\\.lang\\.Class for LingeredAppWithLock\\)$' missing from stdout/stderr

at TestClhsdbJstackLock.main(TestClhsdbJstackLock.java:67)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.RuntimeException: '^\\s+- locked <0x[0-9a-f]+> \\(a java\\.lang\\.Class for LingeredAppWithLock\\)$' missing from stdout/stderr

at jdk.test.lib.process.OutputAnalyzer.shouldMatch(OutputAnalyzer.java:306)
at ClhsdbLauncher.runCmd(ClhsdbLauncher.java:164)
at ClhsdbLauncher.run(ClhsdbLauncher.java:216)
at TestClhsdbJstackLock.main(TestClhsdbJstackLock.java:63)
... 6 more

JavaTest Message: Test threw exception: java.lang.RuntimeException: Test ERROR java.lang.RuntimeException: '^\\s+- locked <0x[0-9a-f]+> \\(a java\\.lang\\.Class for LingeredAppWithLock\\)$' missing from stdout/stderr

JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.RuntimeException: Test ERROR java.lang.RuntimeException: '^\\s+- locked <0x[0-9a-f]+> \\(a java\\.lang\\.Class for LingeredAppWithLock\\)$' missing from stdout/stderr
----------rerun:(32/5791)*----------


The search pattern is:

'^\\s+- locked <0x[0-9a-f]+> \\(a java\\.lang\\.Class for LingeredAppWithLock\\)$'

and the output line that should have matched is:

- locked <0x++++ Eliminated: 1479 Allocate
000000048f454230> ++++ Eliminated: 1321 Allocate
(a java.lang.Class for LingeredAppWithLock)

The "++++ Eliminated: 1479 Allocate" and "++++ Eliminated: 1321 Allocate"
were interleaved in the thread dump output and caused the
pattern match to fail.


Update: Bumping this from P4 -> P2 since this failure mode has now
appeared in a Tier1 CI job set.