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Jimmy Xiang commented on HBASE-9321: ------------------------------------ For this issue, how should be move ahead? To support impersonation, we can either create a new connection/hconnection per user, or reuse the connection among users if proxy user is supported. If one connection per user, we may have many connections if there are many users. To reuse the connection, we can either check the current user so that clients can use doAs, or we can use some client RPC context to pass the user info down with threadlocal variables. > Contention getting the current user in RpcClient$Connection.writeRequest > ------------------------------------------------------------------------ > > Key: HBASE-9321 > URL: https://issues.apache.org/jira/browse/HBASE-9321 > Project: HBase > Issue Type: Bug > Affects Versions: 0.95.2 > Reporter: Jean-Daniel Cryans > Fix For: 0.98.0, 0.96.0 > > Attachments: trunk-9321.patch > > > I've been running tests on clusters with "lots" of regions, about 400, and > I'm seeing weird contention in the client. > This one I see a lot, hundreds and sometimes thousands of threads are blocked > like this: > {noformat} > "htable-pool4-t74" daemon prio=10 tid=0x00007f2254114000 nid=0x2a99 waiting > for monitor entry [0x00007f21f9e94000] > java.lang.Thread.State: BLOCKED (on object monitor) > at > org.apache.hadoop.security.UserGroupInformation.getCurrentUser(UserGroupInformation.java:466) > - waiting to lock <0x00000000fb5ad000> (a java.lang.Class for > org.apache.hadoop.security.UserGroupInformation) > at > org.apache.hadoop.hbase.ipc.RpcClient$Connection.writeRequest(RpcClient.java:1013) > at org.apache.hadoop.hbase.ipc.RpcClient.call(RpcClient.java:1407) > at > org.apache.hadoop.hbase.ipc.RpcClient.callBlockingMethod(RpcClient.java:1634) > at > org.apache.hadoop.hbase.ipc.RpcClient$BlockingRpcChannelImplementation.callBlockingMethod(RpcClient.java:1691) > at > org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$BlockingStub.multi(ClientProtos.java:27339) > at > org.apache.hadoop.hbase.client.MultiServerCallable.call(MultiServerCallable.java:105) > at > org.apache.hadoop.hbase.client.MultiServerCallable.call(MultiServerCallable.java:43) > at > org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:183) > {noformat} > While the holder is doing this: > {noformat} > "htable-pool17-t55" daemon prio=10 tid=0x00007f2244408000 nid=0x2a98 runnable > [0x00007f21f9f95000] > java.lang.Thread.State: RUNNABLE > at java.security.AccessController.getStackAccessControlContext(Native > Method) > at java.security.AccessController.getContext(AccessController.java:487) > at > org.apache.hadoop.security.UserGroupInformation.getCurrentUser(UserGroupInformation.java:466) > - locked <0x00000000fb5ad000> (a java.lang.Class for > org.apache.hadoop.security.UserGroupInformation) > at > org.apache.hadoop.hbase.ipc.RpcClient$Connection.writeRequest(RpcClient.java:1013) > at org.apache.hadoop.hbase.ipc.RpcClient.call(RpcClient.java:1407) > at > org.apache.hadoop.hbase.ipc.RpcClient.callBlockingMethod(RpcClient.java:1634) > at > org.apache.hadoop.hbase.ipc.RpcClient$BlockingRpcChannelImplementation.callBlockingMethod(RpcClient.java:1691) > at > org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$BlockingStub.multi(ClientProtos.java:27339) > at > org.apache.hadoop.hbase.client.MultiServerCallable.call(MultiServerCallable.java:105) > at > org.apache.hadoop.hbase.client.MultiServerCallable.call(MultiServerCallable.java:43) > at > org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:183) > {noformat} -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira