RFR 8205654: serviceability/dcmd/framework/HelpTest.java timed out

[Chris Plummer]

Ok. So this is when you attach using a main classname rather than a pid. 
We could probably make this test use a pid instead, but that doesn't 
actually fix the real issue.

Chris

On 11/29/18 6:12 PM, Daniil Titov wrote:
> Hi Chris,
>
> It attaches to the instrumentation buffer when it is getting a MonitoredVm object inside check() method at jdk.jcmd/share/classes/sun/tools/common/ProcessArgumentMatcher.java:85. It needs a monitored VM to retrieve a main class name ( line 86) and use it on lines 100 and 104  to filter out processes that don't match.
>
> private static boolean check(VirtualMachineDescriptor vmd, String excludeClass, String partialMatch) {
>      81	        String mainClass = null;
>      82	        try {
>      83	            VmIdentifier vmId = new VmIdentifier(vmd.id());
>      84	            MonitoredHost monitoredHost = MonitoredHost.getMonitoredHost(vmId);
>      85	            MonitoredVm monitoredVm = monitoredHost.getMonitoredVm(vmId, -1);
>      86	            mainClass = MonitoredVmUtil.mainClass(monitoredVm, true);
>      87	            monitoredHost.detach(monitoredVm);
>      88	        } catch (NullPointerException npe) {
>      89	            // There is a potential race, where a running java app is being
>      90	            // queried, unfortunately the java app has shutdown after this
>      91	            // method is started but before getMonitoredVM is called.
>      92	            // If this is the case, then the /tmp/hsperfdata_xxx/pid file
>      93	            // will have disappeared and we will get a NullPointerException.
>      94	            // Handle this gracefully....
>      95	            return false;
>      96	        } catch (MonitorException | URISyntaxException e) {
>      97	            return false;
>      98	        }
>      99	
>     100	        if (excludeClass != null && mainClass.equals(excludeClass)) {
>     101	            return false;
>     102	        }
>     103	
>     104	        if (partialMatch != null && mainClass.indexOf(partialMatch) == -1) {
>     105	            return false;
>     106	        }
>     107	
>     108	        return true;
>     109	    }
>
> Below is the stack trace for that:
> attach:-1, Perf (jdk.internal.perf)
> attachImpl:270, Perf (jdk.internal.perf)
> attach:200, Perf (jdk.internal.perf)
> <init>:64, PerfDataBuffer (sun.jvmstat.perfdata.monitor.protocol.local)
> <init>:68, LocalMonitoredVm (sun.jvmstat.perfdata.monitor.protocol.local)
> getMonitoredVm:77, MonitoredHostProvider (sun.jvmstat.perfdata.monitor.protocol.local)
> check:85, ProcessArgumentMatcher (sun.tools.common)
> getVMDs:129, ProcessArgumentMatcher (sun.tools.common)
> getVirtualMachinePids:154, ProcessArgumentMatcher (sun.tools.common)
> main:83, JCmd (sun.tools.jcmd)
>
> Best regards,
> Daniil
>
> On 11/29/18, 5:16 PM, "Chris Plummer" <chris.plummer at oracle.com> wrote:
>
>      Can you remind me why the test is trying to attach to all running java
>      processes.
>      
>      Chris
>      
>      On 11/29/18 1:30 PM, Daniil Titov wrote:
>      > Thank you, David!
>      >
>      > The proposed fix didn't help. It still hangs at some occasions.  Additional tracing showed that when jcmd is invoked with the main class name it iterates over all running Java processes and temporary attaches to them to retrieve the main class name. It hangs while trying to attach to one of the running Java processes. There are numerous Java processes running at the host machine some associated with the test framework itself and another with the tests running in parallel. It is not clear what exact is this particular process since the jcmd hangs before retrieving the process' main class name, but after all tests terminated the process with this id is no longer running.  I have to revoke this review since more investigation is required.
>      >
>      >
>      > Best regards,
>      > Daniil
>      >
>      >
>      >
>      > On 11/11/18, 1:35 PM, "David Holmes" <david.holmes at oracle.com> wrote:
>      >
>      >      Hi Daniil,
>      >
>      >      I took a quick look at this one ... two minor comments
>      >
>      >      The static class names could just be "Process" as they will acquire the
>      >      enclosing class name as part of their own name anyway. As it is this
>      >      gets repeated eg:
>      >
>      >      HelpTest$HelpTestProcess
>      >      InvalidCommandTest$InvalidCommandTestProcess
>      >
>      >      TestJavaProcess.java:
>      >
>      >      39     public static void main(String argv[]) {
>      >
>      >      Nit: Should be "String[] argv" in Java style
>      >
>      >      Thanks,
>      >      David
>      >
>      >      On 10/11/2018 3:18 PM, Daniil Titov wrote:
>      >      > Please review the change that fixes serviceability/dcmd/framework/* tests from a time out. The fix for JDK-8166642 made serviceability/dcmd/framework/* tests non-concurrent to ensure that they don't interact with each other and there are no multiple tests running simultaneously since all they do share the common main class name com.sun.javatest.regtest.agent.MainWrapper. However, it looks like the  tests from other directories still might run in parallel with these tests and they also have com.sun.javatest.regtest.agent.MainWrapper as a main class.
>      >      >
>      >      > The fix  ensures that each serviceability/dcmd/framework/* test uses a Java process with a unique main class name when connecting to this process with jcmd and the main class name.
>      >      >
>      >      > Bug: https://bugs.openjdk.java.net/browse/JDK-8205654
>      >      > Webrev: http://cr.openjdk.java.net/~dtitov/8205654/webrev.001/
>      >      >
>      >      > Best regards,
>      >      > Daniil
>      >      >
>      >      >
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