Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-8229284

[TESTBUG] jdk/internal/platform/cgroup/TestCgroupMetrics.java fails for - memory:getMemoryUsage

    Details

    • Subcomponent:
    • Resolved In Build:
      b13
    • CPU:
      generic
    • OS:
      linux

      Backports

        Description

        We sometimes see failures in the jtreg test jdk/internal/platform/cgroup/TestCgroupMetrics.java .
        Failures look like :

        java.lang.RuntimeException: Test failed for - memory:getMemoryUsage, expected [56019386368], got [56200986624]
        at jdk.test.lib.containers.cgroup.MetricsTester.fail(MetricsTester.java:207)
        at jdk.test.lib.containers.cgroup.MetricsTester.testMemoryUsage(MetricsTester.java:597)
        at TestCgroupMetrics.main(TestCgroupMetrics.java:53)
        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)


        Looking at the coding in MetricsTester.java we expect that “memory.usage_in_bytes” gets larger after an additional allocation of 64 M.
        However this is sometimes not the case. The reason is not fully clear.
        Might be that a GC kicked in and freed space; or for some reasons OS pages were freed.
        Maybe also the "memory.usage_in_bytes” counter is not so reliable (by design? or bug ?) .
        Coding from MetricsTester.java :

            public void testMemoryUsage() throws Exception {
                Metrics metrics = Metrics.systemMetrics();
                long memoryMaxUsage = metrics.getMemoryMaxUsage();
                long memoryUsage = metrics.getMemoryUsage();

                byte[] bb = new byte[64*1024*1024]; // 64M - here we expect an increase of memory.usage_in_bytes

                long newMemoryMaxUsage = metrics.getMemoryMaxUsage();
                long newMemoryUsage = metrics.getMemoryUsage();

                if(newMemoryMaxUsage < memoryMaxUsage) {
                    fail(SubSystem.MEMORY, "getMemoryMaxUsage", newMemoryMaxUsage,
                            memoryMaxUsage);
                }

                if(newMemoryUsage < memoryUsage) {
                    fail(SubSystem.MEMORY, "getMemoryUsage", newMemoryUsage, memoryUsage); // line 597 triggers the failure in MetricsTester.java
                }
            }


        probably we should make the test more reliable and add a little loop with allocations (and do not fail on the first one) .

          Attachments

            Issue Links

              Activity

                People

                • Assignee:
                  mbaesken Matthias Baesken
                  Reporter:
                  mbaesken Matthias Baesken
                • Votes:
                  0 Vote for this issue
                  Watchers:
                  5 Start watching this issue

                  Dates

                  • Created:
                    Updated:
                    Resolved: