RFR: 8131745: java/lang/management/ThreadMXBean/AllThreadIds.java still fails intermittently

[Daniil Titov]

Hi Alex, Serguei, and Martin,

Thank you for your comments. Please review a new version of the fix that addresses them, specifically:
1)  Replaces a double loop in checkAllThreadsAlive() with a code that uses collections and containsAll()  method.
2)  Restores the checks for other ThreadMXBean methods (getThreadCount(), getTotalStartedThreadCount(), getPeakThreadCount()) but with more relaxed conditions.
3)  Relaxes the check inside checkThreadIds() method


[1] http://cr.openjdk.java.net/~dtitov/8131745/webrev.03/ 
[2] https://bugs.openjdk.java.net/browse/JDK-8131745 

Thank you,
Daniil

On 6/1/20, 5:06 PM, "Alex Menkov" <alexey.menkov at oracle.com> wrote:

    Hi Daniil,

    1. before the fix checkLiveThreads() tested 
    ThreadMXBean.getThreadCount(), but now as far as I see it tests 
    Thread.getAllStackTraces();

    2.
      237     private static void checkThreadIds() throws InterruptedException {
      238         long[] list = mbean.getAllThreadIds();
      239
      240         waitTillEquals(
      241             list.length,
      242             ()->(long)mbean.getThreadCount(),
      243             "Array length returned by " +
      244                 "getAllThreadIds() = %1$d not matched count = 
    ${provided}",
      245             ()->list.length
      246         );
      247     }

    I suppose purpose of waitTillEquals() is to handle creation/termination 
    of VM internal threads.
    But if some internal thread terminates after mbean.getAllThreadIds() and 
    before 1st mbean.getThreadCount() call and then VM does not need to 
    restart it, waitTillEquals will wait forever.

    --alex


    On 05/29/2020 16:28, Daniil Titov wrote:
    > Hi Alex and Serguei,
    > 
    > Please review a new version of the change [1] that makes sure that the test counts
    > only the threads it creates and ignores  Internal threads VM might create or  destroy.
    > 
    > Testing: Running this test in Mach5 with Graal on several hundred times ,
    >   tier1-tier3 tests  are in progress.
    > 
    > [1] http://cr.openjdk.java.net/~dtitov/8131745/webrev.02/
    > [2] https://bugs.openjdk.java.net/browse/JDK-8131745
    > 
    > Thank you,
    > Daniil
    > 
    > On 5/22/20, 10:26 AM, "Alex Menkov" <alexey.menkov at oracle.com> wrote:
    > 
    >      Hi Daniil,
    > 
    >      I'm not sure all this retry logic is a good way.
    >      As mentioned in jira the most important part of the testing is ensuring
    >      that you find all the created threads when they are alive, and you don't
    >      find them when they are dead. The actual thread count checking is not
    >      that important.
    >      I agree with this and I'd just simplify the test by removing checks for
    >      thread count. VM may create and destroy internal threads when it needs it.
    > 
    >      --alex
    > 
    >      On 05/18/2020 10:31, Daniil Titov wrote:
    >      > Please review the change [1] that fixes an intermittent failure of the test.
    >      >
    >      > This test creates and destroys a given number of daemon/user threads and validates the count of those started/stopped threads against values returned from ThreadMXBean thread counts.  The problem here is that if some internal threads is started ( e.g. " HotSpotGraalManagement Bean Registration"), or destroyed  (e.g. "JVMCI CompilerThread ") the test hangs waiting for expected number of live threads.
    >      >
    >      > The fix limits the time the test is waiting for desired number of live threads and in case if this limit is exceeded the test repeats itself.
    >      >
    >      > Testing. Test with Graal on and Mach5 tier1-tier7 test passed.
    >      >
    >      > [1] http://cr.openjdk.java.net/~dtitov/8131745/webrev.01
    >      > [2] https://bugs.openjdk.java.net/browse/JDK-8131745
    >      >
    >      > Thank you,
    >      > Daniil
    >      >
    >      >
    >      >
    > 
    >