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https://issues.apache.org/jira/browse/HDFS-13821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16577836#comment-16577836
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Yiqun Lin commented on HDFS-13821:
----------------------------------
Looks like a interesting scenery, [~ferhui]. Can you describe more for this? If
the cache is updating when you found threads blocked by local cache? For the
behavior of disabling cache, it will cause frequency read operations to state
store. It won' t be a fast way.
> RBF:add dfs.federation.router.mount-table.cache.enable so that users can
> disable cache
> --------------------------------------------------------------------------------------
>
> Key: HDFS-13821
> URL: https://issues.apache.org/jira/browse/HDFS-13821
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs
> Affects Versions: 3.1.0, 2.9.1, 3.0.3
> Reporter: Fei Hui
> Priority: Major
> Attachments: HDFS-13821.001.patch, image-2018-08-13-11-27-49-023.png
>
>
> When i test rbf, if found performance problem.
> I found that ProxyAvgTime From Ganglia is so high, i run jstack on Router and
> get the following stack frames
> {quote}
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x00000005c264acd8> (a
> java.util.concurrent.locks.ReentrantLock$NonfairSync)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
> at
> java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
> at
> java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
> at
> com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2249)
> at
> com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2228)
> at com.google.common.cache.LocalCache.get(LocalCache.java:3965)
> at
> com.google.common.cache.LocalCache$LocalManualCache.get(LocalCache.java:4764)
> at
> org.apache.hadoop.hdfs.server.federation.resolver.MountTableResolver.getDestinationForPath(MountTableResolver.java:380)
> at
> org.apache.hadoop.hdfs.server.federation.router.RouterRpcServer.getLocationsForPath(RouterRpcServer.java:2104)
> at
> org.apache.hadoop.hdfs.server.federation.router.RouterRpcServer.getLocationsForPath(RouterRpcServer.java:2087)
> at
> org.apache.hadoop.hdfs.server.federation.router.RouterRpcServer.getListing(RouterRpcServer.java:1050)
> at
> org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.getListing(ClientNamenodeProtocolServerSideTranslatorPB.java:640)
> at
> org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
> at
> org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:616)
> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:982)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2115)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2111)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:422)
> {quote}
> Many threads blocked on *LocalCache*
> After disable the cache, ProxyAvgTime is down as follow showed
> !image-2018-08-13-11-27-49-023.png!
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