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https://issues.apache.org/jira/browse/CASSANDRA-9549?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Ivar Thorson updated CASSANDRA-9549:
------------------------------------
    Description: 
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:

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]

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

This might be related to [CASSANDRA-8723]?


  was:
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:

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]

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




> Memory leak 
> ------------
>
>                 Key: CASSANDRA-9549
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9549
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         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
>            Priority: Critical
>         Attachments: cassandra.yaml, cpu-load.png, memoryuse.png, 
> 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$Node objects. We took heap dumps 
> over a 2 day period, and watched the number of Node objects go from 4M, to 
> 19M, to 36M, and eventually about 65M objects before the node stops 
> responding. The screen capture of our heap dump is from the 19M measurement.
> Load on the cluster is minimal. We can see this effect even with only a 
> handful of writes per second. (See attachments for Opscenter snapshots during 
> very light loads and heavier loads). Even with only 5 reads a sec we see this 
> behavior.
> Log files show repeated errors in Ref.java:181 and Ref.java:279 and "LEAK 
> detected" messages:
> ERROR [CompactionExecutor:557] 2015-06-01 18:27:36,978 Ref.java:279 - Error 
> when closing class 
> org.apache.cassandra.io.sstable.SSTableReader$InstanceTidier@1302301946:/data1/data/ourtablegoeshere-ka-1150
> java.util.concurrent.RejectedExecutionException: Task 
> java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask@32680b31 
> rejected from 
> org.apache.cassandra.concurrent.DebuggableScheduledThreadPoolExecutor@573464d6[Terminated,
>  pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 1644]
> ERROR [Reference-Reaper:1] 2015-06-01 18:27:37,083 Ref.java:181 - LEAK 
> DETECTED: a reference 
> (org.apache.cassandra.utils.concurrent.Ref$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
> This might be related to [CASSANDRA-8723]?



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