The following test timed out in the JDK16 CI:

serviceability/sa/ClhsdbPstack.java#id1
serviceability/sa/ClhsdbPmap.java#id1
serviceability/sa/ClhsdbFindPC.java#id3
serviceability/sa/ClhsdbFindPC.java#id1

Here's a snippet from the ClhsdbPstack.java#id1 log file:

#section:main
----------messages:(6/229)----------
command: main ClhsdbPstack true
reason: User specified action: run main/othervm/timeout=240 ClhsdbPstack true
Mode: othervm [/othervm specified]
Timeout information:
--- Timeout information end.
elapsed time (seconds): 1084.922
----------configuration:(0/0)----------
----------System.out:(10/1877)----------
Starting ClhsdbPstack test: withCore==true
Command line: ['/mesos/work_dir/jib-master/install/jdk-16+16-641/macosx-x64-debug.jdk/jdk-16/fastdebug/bin/java' '-XX:MaxRAMPercentage=12' '-Djava.io.tmpdir=/mesos/work_dir/slaves/4076d11c-c6ed-4d07-84c1-4ab8d55cd975-S106665/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ab14e180-3147-48f9-b585-acbc7bf5f30f/runs/8f56fe9e-4aec-448a-a1f3-4f047a01b049/testoutput/test-support/jtreg_open_test_hotspot_jtreg_tier1_serviceability/tmp' '-XX:+CreateCoredumpOnCrash' '-Djava.library.path=/mesos/work_dir/jib-master/install/jdk-16+16-641/macosx-x64-debug.test/hotspot/jtreg/native' '-cp' '/mesos/work_dir/slaves/4076d11c-c6ed-4d07-84c1-4ab8d55cd975-S106665/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ab14e180-3147-48f9-b585-acbc7bf5f30f/runs/8f56fe9e-4aec-448a-a1f3-4f047a01b049/testoutput/test-support/jtreg_open_test_hotspot_jtreg_tier1_serviceability/classes/1/serviceability/sa/ClhsdbPstack_id1.d:/mesos/work_dir/slaves/4076d11c-c6ed-4d07-84c1-4ab8d55cd975-S106665/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ab14e180-3147-48f9-b585-acbc7bf5f30f/runs/8f56fe9e-4aec-448a-a1f3-4f047a01b049/testoutput/test-support/jtreg_open_test_hotspot_jtreg_tier1_serviceability/classes/1/test/lib' 'jdk.test.lib.apps.LingeredApp' 'dfc81e24-0db3-4dc6-a154-7ec498f5c22f.lck' 'forceCrash']
[2020-09-10T16:35:45.756509Z] Gathering output for process 51330
[2020-09-10T16:35:45.808764Z] Waiting for completion for process 51330
[2020-09-10T16:35:45.808947Z] Waiting for completion finished for process 51330
Output and diagnostic info for process 51330 was saved into 'pid-51330-output.log'
[2020-09-10T16:35:45.857753Z] Waiting for completion for process 51330
[2020-09-10T16:35:45.857905Z] Waiting for completion finished for process 51330
Run test with ulimit -c: unlimited
Timeout refired 960 times
----------System.err:(20/1281)----------
java.lang.RuntimeException: Test ERROR java.io.IOException: App waiting timeout
at ClhsdbPstack.main(ClhsdbPstack.java:93)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
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.io.IOException: App waiting timeout
at jdk.test.lib.apps.LingeredApp.waitAppReady(LingeredApp.java:265)
at jdk.test.lib.apps.LingeredApp.waitAppReady(LingeredApp.java:295)
at jdk.test.lib.apps.LingeredApp.startAppExactJvmOpts(LingeredApp.java:417)
at jdk.test.lib.apps.LingeredApp.startApp(LingeredApp.java:432)
at ClhsdbPstack.main(ClhsdbPstack.java:63)
... 6 more

JavaTest Message: Test threw exception: java.lang.RuntimeException: Test ERROR java.io.IOException: App waiting timeout
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.RuntimeException: Test ERROR java.io.IOException: App waiting timeout
----------rerun:(33/6619)*----------

This issue was previously addressed via:

    JDK-8249150 SA core file tests sometimes time out on OSX with "java.io.IOException: App waiting timeout"

Since this is a Tier1 test failure, this bug would normally
start out as a P2. However, this failure mode tends to be
intermittent so I'm starting it as a P3.