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https://issues.apache.org/jira/browse/CASSANDRA-5345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13946228#comment-13946228
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Matt Byrd commented on CASSANDRA-5345:
--------------------------------------
The cluster in question was running on 1.0.7, however the code in question has
remained static since well before that and doesn't look to have changed since.
(though admittedly the problem could somehow be being caused elsewhere, jvm
maybe?)
I've upped the priority to major.
Have you been able to reproduce? or seen the problem anywhere else?
Any further details about your environment is set up and how you deploy may
also help those trying to reproduce.
Some common but perhaps co-incidental things about the two occurrences:
1. virtual machines (though not both AWS)
2. multi D.C , wouldn't have though this would be relevant but Arya does seem
to see the problem after removing a d.c.
3. Slightly old Jvm versions...
I no longer have access to the cluster where we saw this previously but let me
know if I can help in any other way.
> Potential problem with GarbageCollectorMXBean
> ---------------------------------------------
>
> Key: CASSANDRA-5345
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5345
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.0.7
> Environment: JVM:JVM vendor/version: Java HotSpot(TM) 64-Bit Server
> VM/1.6.0_30 typical 6 node 2 availability zone Mutli DC cluster on linux vms
> with
> and mx4j-tools.jar and jna.jar both on path. Default configuration bar token
> setup(equispaced), sensible cassandra-topology.properties file and use of
> said snitch.
> Reporter: Matt Byrd
> Assignee: Ryan McGuire
>
> I am not certain this is definitely a bug, but I thought it might be worth
> posting to see if someone with more JVM//JMX knowledge could disprove my
> reasoning. Apologies if I've failed to understand something.
> We've seen an intermittent problem where there is an uncaught exception in
> the scheduled task of logging gc results in GcInspector.java:
> {code}
> ...
> ERROR [ScheduledTasks:1] 2013-03-08 01:09:06,335
> AbstractCassandraDaemon.java (line 139) Fatal exception in thread
> Thread[ScheduledTasks:1,5,main]
> java.lang.reflect.UndeclaredThrowableException
> at $Proxy0.getName(Unknown Source)
> at
> org.apache.cassandra.service.GCInspector.logGCResults(GCInspector.java:95)
> at
> org.apache.cassandra.service.GCInspector.access$000(GCInspector.java:41)
> at org.apache.cassandra.service.GCInspector$1.run(GCInspector.java:85)
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
> at
> java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
> at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
> at
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
> at
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:180)
> at
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:204)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:662)
> Caused by: javax.management.InstanceNotFoundException:
> java.lang:name=ParNew,type=GarbageCollector
> at
> com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getMBean(DefaultMBeanServerInterceptor.java:1094)
> at
> com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getAttribute(DefaultMBeanServerInterceptor.java:662)
> at
> com.sun.jmx.mbeanserver.JmxMBeanServer.getAttribute(JmxMBeanServer.java:638)
> at
> com.sun.jmx.mbeanserver.MXBeanProxy$GetHandler.invoke(MXBeanProxy.java:106)
> at com.sun.jmx.mbeanserver.MXBeanProxy.invoke(MXBeanProxy.java:148)
> at
> javax.management.MBeanServerInvocationHandler.invoke(MBeanServerInvocationHandler.java:248)
> ... 13 more
> ...
> {code}
> I think the problem, may be caused by the following reasoning:
> In GcInspector we populate a list of mxbeans when the GcInspector instance is
> instantiated:
> {code}
> ...
> List<GarbageCollectorMXBean> beans = new ArrayList<GarbageCollectorMXBean>();
> MBeanServer server = ManagementFactory.getPlatformMBeanServer();
> try
> {
> ObjectName gcName = new
> ObjectName(ManagementFactory.GARBAGE_COLLECTOR_MXBEAN_DOMAIN_TYPE + ",*");
> for (ObjectName name : server.queryNames(gcName, null))
> {
> GarbageCollectorMXBean gc =
> ManagementFactory.newPlatformMXBeanProxy(server, name.getCanonicalName(),
> GarbageCollectorMXBean.class);
> beans.add(gc);
> }
> }
> catch (Exception e)
> {
> throw new RuntimeException(e);
> }
> ...
> {code}
> Cassandra then periodically calls:
> {code}
> ...
> private void logGCResults()
> {
> for (GarbageCollectorMXBean gc : beans)
> {
> Long previousTotal = gctimes.get(gc.getName());
> ...
> {code}
> In the oracle javadocs, they seem to suggest that these beans could disappear
> at any time.(I'm not sure why when or how this might happen)
> http://docs.oracle.com/javase/6/docs/api/
> See: getGarbageCollectorMXBeans
> {code}
> ...
> public static List<GarbageCollectorMXBean> getGarbageCollectorMXBeans()
> Returns a list of GarbageCollectorMXBean objects in the Java virtual machine.
> The Java virtual machine may have one or more GarbageCollectorMXBean objects.
> It may add or remove GarbageCollectorMXBean during execution.
> Returns:
> a list of GarbageCollectorMXBean objects.
> ...
> {code}
> Correct me if I'm wrong, but do you think this might be causing the problem?
> That somehow the JVM decides to remove the GarbageCollectorMXBean temporarily
> or permanently (causing said exception) and if this is expected behaviour,
> should it be handled in some way?
> Also I'd like to point out that this may be an issue on other versions as
> well as I don't believe this code has changed in quite a long time.
> Unfortunately I haven't been able to reproduce this outside of the production
> environment, if you have any tips, questions or are able to explain//disprove
> my concerns, I'd be very grateful.
> Thanks,
> Matt
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