When running "jhsdb jmap" on on java process, on occasion it will get stuck, I believe in an infinite loop, resulting in a timeout if it happens during a test. For the most part our jmap tests never see this, I believe because all threads are idle (blocked). When you have an active process, you see this failure somewhat frequently. The new HeapDumpTestWithActiveProcess.java test uncovers it on about 2% of runs on linux-x64.

I believe this issue was introduced by JDK-6760477, which added stack traces to the jmap heap dump.

Note this issue is also covered by JDK-8230872, which I will be closing once I get appropriate CRs files.

This failure is most commonly noted when HeapDumpTestWithActiveProcess.java times out. In the log you will see:

----------System.out:(230/19729)----------
Starting Jshell
[JShell]:/opt/mach5/mesos/work_dir/jib-master/install/2019-09-30-1717232.chris.plummer.jdk.clean/linux-x64-debug.jdk/jdk-14/fastdebug/bin/jshell
[JShell] | Welcome to JShell -- Version 14-internal
[JShell] | For an introduction type: /help intro
Jshell Started in 3926ms
Starting jmap against 19214
[2019-09-30T17:54:36.169781Z] Gathering output for process 19271
Timeout refired 960 times
...
java.lang.RuntimeException: Test ERROR java.lang.RuntimeException: Expected to get exit value of [0]
at JShellHeapDumpTest.launch(JShellHeapDumpTest.java:79)
at JShellHeapDumpTest.launch(JShellHeapDumpTest.java:94)
at JShellHeapDumpTest.testHeapDump(JShellHeapDumpTest.java:115)
at JShellHeapDumpTest.main(JShellHeapDumpTest.java:162)
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:830)
Caused by: java.lang.RuntimeException: Expected to get exit value of [0]
at jdk.test.lib.process.OutputAnalyzer.shouldHaveExitValue(OutputAnalyzer.java:455)
at JShellHeapDumpTest.launch(JShellHeapDumpTest.java:77)
... 9 more

Here's the backtrace you see if you look at the jmap process in the processes.html file after HeapDumpTestWithActiveProcess.java gets a timeout:

at sun.jvm.hotspot.types.basic.BasicTypeDataBase.findDynamicTypeForAddress(jdk.hotspot.agent@14-internal/BasicTypeDataBase.java:328)
at sun.jvm.hotspot.runtime.VirtualBaseConstructor.instantiateWrapperFor(jdk.hotspot.agent@14-internal/VirtualBaseConstructor.java:102)
at sun.jvm.hotspot.utilities.GrowableArray.at(jdk.hotspot.agent@14-internal/GrowableArray.java:61)
at sun.jvm.hotspot.code.CodeCache.findBlobUnsafe(jdk.hotspot.agent@14-internal/CodeCache.java:102)
at sun.jvm.hotspot.code.CodeCache.findBlob(jdk.hotspot.agent@14-internal/CodeCache.java:85)
at sun.jvm.hotspot.runtime.x86.X86Frame.sender(jdk.hotspot.agent@14-internal/X86Frame.java:282)
at sun.jvm.hotspot.runtime.Frame.sender(jdk.hotspot.agent@14-internal/Frame.java:205)
at sun.jvm.hotspot.runtime.amd64.AMD64CurrentFrameGuess.run(jdk.hotspot.agent@14-internal/AMD64CurrentFrameGuess.java:140)
at sun.jvm.hotspot.runtime.linux_amd64.LinuxAMD64JavaThreadPDAccess.getCurrentFrameGuess(jdk.hotspot.agent@14-internal/LinuxAMD64JavaThreadPDAccess.java:95)
at sun.jvm.hotspot.runtime.JavaThread.getCurrentFrameGuess(jdk.hotspot.agent@14-internal/JavaThread.java:265)
at sun.jvm.hotspot.runtime.JavaThread.getLastJavaVFrameDbg(jdk.hotspot.agent@14-internal/JavaThread.java:227)
at sun.jvm.hotspot.runtime.ThreadStackTrace.dumpStack(jdk.hotspot.agent@14-internal/ThreadStackTrace.java:54)
at sun.jvm.hotspot.utilities.HeapHprofBinWriter.dumpStackTraces(jdk.hotspot.agent@14-internal/HeapHprofBinWriter.java:718)
at sun.jvm.hotspot.utilities.HeapHprofBinWriter.write(jdk.hotspot.agent@14-internal/HeapHprofBinWriter.java:439)
- locked <0x0000000415c585c8> (a sun.jvm.hotspot.utilities.HeapHprofBinWriter)
at sun.jvm.hotspot.tools.JMap.writeHeapHprofBin(jdk.hotspot.agent@14-internal/JMap.java:182)
at sun.jvm.hotspot.tools.JMap.run(jdk.hotspot.agent@14-internal/JMap.java:97)
at sun.jvm.hotspot.tools.Tool.startInternal(jdk.hotspot.agent@14-internal/Tool.java:262)
at sun.jvm.hotspot.tools.Tool.start(jdk.hotspot.agent@14-internal/Tool.java:225)
at sun.jvm.hotspot.tools.Tool.execute(jdk.hotspot.agent@14-internal/Tool.java:118)
at sun.jvm.hotspot.tools.JMap.main(jdk.hotspot.agent@14-internal/JMap.java:176)
at sun.jvm.hotspot.SALauncher.runJMAP(jdk.hotspot.agent@14-internal/SALauncher.java:321)
at sun.jvm.hotspot.SALauncher$$Lambda$4/0x0000000800ba5c40.accept(jdk.hotspot.agent@14-internal/Unknown Source)
at sun.jvm.hotspot.SALauncher.main(jdk.hotspot.agent@14-internal/SALauncher.java:406)