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https://issues.apache.org/jira/browse/CASSANDRA-9549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15233823#comment-15233823
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stone commented on CASSANDRA-9549:
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could you take a summary after resolving the issue?
why this happen?,how to resolve?
actually,it's hard to find the answer when people met the same issue.

> Memory leak in Ref.GlobalState due to pathological 
> ConcurrentLinkedQueue.remove behaviour
> -----------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-9549
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9549
>             Project: Cassandra
>          Issue Type: Bug
>         Environment: Cassandra 2.1.5. 9 node cluster in EC2 (m1.large nodes, 
> 2 cores 7.5G memory, 800G platter for cassandra data, root partition and 
> commit log are on SSD EBS with sufficient IOPS), 3 nodes/availablity zone, 1 
> replica/zone
> JVM: /usr/java/jdk1.8.0_40/jre/bin/java 
> JVM Flags besides CP: -ea -javaagent:/usr/share/cassandra/lib/jamm-0.3.0.jar 
> -XX:+CMSClassUnloadingEnabled -XX:+UseThreadPriorities 
> -XX:ThreadPriorityPolicy=42 -Xms2G -Xmx2G -Xmn200M 
> -XX:+HeapDumpOnOutOfMemoryError -Xss256k -XX:StringTableSize=1000003 
> -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled 
> -XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=1 
> -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly 
> -XX:+UseTLAB -XX:CompileCommandFile=/etc/cassandra/conf/hotspot_compiler 
> -XX:CMSWaitDuration=10000 -XX:+CMSParallelInitialMarkEnabled 
> -XX:+CMSEdenChunksRecordAlways -XX:CMSWaitDuration=10000 -XX:+UseCondCardMark 
> -Djava.net.preferIPv4Stack=true -Dcom.sun.management.jmxremote.port=7199 
> -Dcom.sun.management.jmxremote.rmi.port=7199 
> -Dcom.sun.management.jmxremote.ssl=false 
> -Dcom.sun.management.jmxremote.authenticate=false 
> -Dlogback.configurationFile=logback.xml -Dcassandra.logdir=/var/log/cassandra 
> -Dcassandra.storagedir= -Dcassandra-pidfile=/var/run/cassandra/cassandra.pid 
> Kernel: Linux 2.6.32-504.16.2.el6.x86_64 #1 SMP x86_64 x86_64 x86_64 GNU/Linux
>            Reporter: Ivar Thorson
>            Assignee: Benedict
>            Priority: Critical
>             Fix For: 2.1.7
>
>         Attachments: c4_system.log, c7fromboot.zip, cassandra.yaml, 
> cpu-load.png, memoryuse.png, ref-java-errors.jpeg, suspect.png, two-loads.png
>
>
> We have been experiencing a severe memory leak with Cassandra 2.1.5 that, 
> over the period of a couple of days, eventually consumes all of the available 
> JVM heap space, putting the JVM into GC hell where it keeps trying CMS 
> collection but can't free up any heap space. This pattern happens for every 
> node in our cluster and is requiring rolling cassandra restarts just to keep 
> the cluster running. We have upgraded the cluster per Datastax docs from the 
> 2.0 branch a couple of months ago and have been using the data from this 
> cluster for more than a year without problem.
> As the heap fills up with non-GC-able objects, the CPU/OS load average grows 
> along with it. Heap dumps reveal an increasing number of 
> java.util.concurrent.ConcurrentLinkedQueue$Node objects. We took heap dumps 
> over a 2 day period, and watched the number of Node objects go from 4M, to 
> 19M, to 36M, and eventually about 65M objects before the node stops 
> responding. The screen capture of our heap dump is from the 19M measurement.
> Load on the cluster is minimal. We can see this effect even with only a 
> handful of writes per second. (See attachments for Opscenter snapshots during 
> very light loads and heavier loads). Even with only 5 reads a sec we see this 
> behavior.
> Log files show repeated errors in Ref.java:181 and Ref.java:279 and "LEAK 
> detected" messages:
> {code}
> ERROR [CompactionExecutor:557] 2015-06-01 18:27:36,978 Ref.java:279 - Error 
> when closing class 
> org.apache.cassandra.io.sstable.SSTableReader$InstanceTidier@1302301946:/data1/data/ourtablegoeshere-ka-1150
> java.util.concurrent.RejectedExecutionException: Task 
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask@32680b31 
> rejected from 
> org.apache.cassandra.concurrent.DebuggableScheduledThreadPoolExecutor@573464d6[Terminated,
>  pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 1644]
> {code}
> {code}
> ERROR [Reference-Reaper:1] 2015-06-01 18:27:37,083 Ref.java:181 - LEAK 
> DETECTED: a reference 
> (org.apache.cassandra.utils.concurrent.Ref$State@74b5df92) to class 
> org.apache.cassandra.io.sstable.SSTableReader$DescriptorTypeTidy@2054303604:/data2/data/ourtablegoeshere-ka-1151
>  was not released before the reference was garbage collected
> {code}
> This might be related to [CASSANDRA-8723]?



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