jvmti/scenarios/sampling tests fail with "Found unexpected number of tested threads (ThreadWaiting)"

The following failure was spotted in the JDK14 CI:

vmTestbase/nsk/jvmti/scenarios/sampling/SP04/sp04t001/TestDescription.java

Here's a snippet from the log file:

----------System.out:(8/1754)----------
run [ExecDriver, --java, -agentlib:sp04t001=-waittime=5 threads=10, nsk.jvmti.scenarios.sampling.SP04.sp04t001]
exec [/scratch/mesos/jib-master/install/jdk-14+1-2/macosx-x64-debug.jdk/jdk-14/fastdebug/bin/java, -XX:MaxRAMPercentage=4, -cp, /scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/vmTestbase/nsk/jvmti/scenarios/sampling/SP04/sp04t001/TestDescription.d:/scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/vmTestbase:/scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/test/lib, -Djava.library.path=/scratch/mesos/jib-master/install/jdk-14+1-2/macosx-x64-debug.test/hotspot/jtreg/native, -agentlib:sp04t001=-waittime=5 threads=10, nsk.jvmti.scenarios.sampling.SP04.sp04t001]
The following fake exception stacktrace is for failure analysis.
nsk.share.Fake_Exception_for_RULE_Creation: (sp04t001.cpp:212) Found unexpected number of tested threads (ThreadWaiting):
at nsk_lvcomplain(nsk_tools.cpp:172)
# ERROR: sp04t001.cpp, 212: Found unexpected number of tested threads (ThreadWaiting):
# found: 9
# expected: 10
----------System.err:(18/5074)----------
java.lang.AssertionError: [/scratch/mesos/jib-master/install/jdk-14+1-2/macosx-x64-debug.jdk/jdk-14/fastdebug/bin/java, -XX:MaxRAMPercentage=4, -cp, /scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/vmTestbase/nsk/jvmti/scenarios/sampling/SP04/sp04t001/TestDescription.d:/scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/vmTestbase:/scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/test/lib, -Djava.library.path=/scratch/mesos/jib-master/install/jdk-14+1-2/macosx-x64-debug.test/hotspot/jtreg/native, -agentlib:sp04t001=-waittime=5 threads=10, nsk.jvmti.scenarios.sampling.SP04.sp04t001] exit code is 97
at ExecDriver.main(ExecDriver.java:137)
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:567)
at PropertyResolvingWrapper.main(PropertyResolvingWrapper.java:104)
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:567)
at com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
at java.base/java.lang.Thread.run(Thread.java:830)

JavaTest Message: Test threw exception: java.lang.AssertionError: [/scratch/mesos/jib-master/install/jdk-14+1-2/macosx-x64-debug.jdk/jdk-14/fastdebug/bin/java, -XX:MaxRAMPercentage=4, -cp, /scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/vmTestbase/nsk/jvmti/scenarios/sampling/SP04/sp04t001/TestDescription.d:/scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/vmTestbase:/scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/test/lib, -Djava.library.path=/scratch/mesos/jib-master/install/jdk-14+1-2/macosx-x64-debug.test/hotspot/jtreg/native, -agentlib:sp04t001=-waittime=5 threads=10, nsk.jvmti.scenarios.sampling.SP04.sp04t001] exit code is 97
JavaTest Message: shutting down test

STATUS:Failed.`main' threw exception: java.lang.AssertionError: [/scratch/mesos/jib-master/install/jdk-14+1-2/macosx-x64-debug.jdk/jdk-14/fastdebug/bin/java, -XX:MaxRAMPercentage=4, -cp, /scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/vmTestbase/nsk/jvmti/scenarios/sampling/SP04/sp04t001/TestDescription.d:/scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/vmTestbase:/scratch/mesos/slaves/8cd6f162-51f6-4a7f-a76b-32ddeb30fb11-S21600/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/ce93843b-b09f-4078-b3fb-b8fee48bf8eb/runs/b62c33ce-35b6-43e0-8e47-45400ff74d22/testoutput/test-support/jtreg_open_test_hotspot_jtreg_vmTestbase_nsk_jvmti/classes/5/test/lib, -Djava.library.path=/scratch/mesos/jib-master/install/jdk-14+1-2/macosx-x64-debug.test/hotspot/jtreg/native, -agentlib:sp04t001=-waittime=5 threads=10, nsk.jvmti.scenarios.sampling.SP04.sp04t001] exit code is 97
----------rerun:(30/6304)*----------