ERROR [ShortCircuitCache_SlotReleaser] shortcircuit.ShortCircuitCache: ShortCircuitCache(0x1448fd5c): failed to release short-circuit shared memory slot Slot(slotIdx=36, shm=DfsClientShm(4e51f83de136d886e5af24a3ee1103e5)) by sending ReleaseShortCircuitAccessRequestProto to /var/lib/hadoop-hdfs/dn_socket.  Closing shared memory segment.
java.net.ConnectException: connect(2) error: Connection refused when trying to connect to '/var/lib/hadoop-hdfs/dn_socket'
        at org.apache.hadoop.net.unix.DomainSocket.connect0(Native Method)
        at org.apache.hadoop.net.unix.DomainSocket.connect(DomainSocket.java:250)
        at org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache$SlotReleaser.run(ShortCircuitCache.java:198)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
2017-10-31 01:14:44,916 WARN  [ShortCircuitCache_SlotReleaser] shortcircuit.DfsClientShmManager: EndpointShmManager(DatanodeInfoWithStorage[HadoopDN2:50010,DS-b07091a9-234e-488a-aac7-4bff28ede1ab,DISK], parent=ShortCircuitShmManager(4acc97a7)): error shutting down shm: got IOException calling shutdown(SHUT_RDWR)
java.nio.channels.ClosedChannelException
        at org.apache.hadoop.util.CloseableReferenceCount.reference(CloseableReferenceCount.java:57)
        at org.apache.hadoop.net.unix.DomainSocket.shutdown(DomainSocket.java:387)
        at org.apache.hadoop.hdfs.shortcircuit.DfsClientShmManager$EndpointShmManager.shutdown(DfsClientShmManager.java:379)
        at org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache$SlotReleaser.run(ShortCircuitCache.java:223)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)