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He Xiaoqiao commented on HDFS-10453: ------------------------------------ I checked the failed UTs and tested locally, it seems to work fine and might not relate to this patch, please double check at your convenience. [~arpitagarwal] > ReplicationMonitor thread could stuck for long time due to the race between > replication and delete of same file in a large cluster. > ----------------------------------------------------------------------------------------------------------------------------------- > > Key: HDFS-10453 > URL: https://issues.apache.org/jira/browse/HDFS-10453 > Project: Hadoop HDFS > Issue Type: Bug > Components: namenode > Affects Versions: 2.4.1, 2.5.2, 2.7.1, 2.6.4 > Reporter: He Xiaoqiao > Assignee: He Xiaoqiao > Priority: Major > Fix For: 2.7.6 > > Attachments: HDFS-10453-branch-2.001.patch, > HDFS-10453-branch-2.003.patch, HDFS-10453-branch-2.7.004.patch, > HDFS-10453-branch-2.7.005.patch, HDFS-10453-branch-2.7.006.patch, > HDFS-10453-branch-2.7.007.patch, HDFS-10453-branch-2.7.008.patch, > HDFS-10453-branch-2.7.009.patch, HDFS-10453-branch-2.8.001.patch, > HDFS-10453-branch-2.8.002.patch, HDFS-10453-branch-2.9.001.patch, > HDFS-10453-branch-2.9.002.patch, HDFS-10453-branch-3.0.001.patch, > HDFS-10453-branch-3.0.002.patch, HDFS-10453-trunk.001.patch, > HDFS-10453-trunk.002.patch, HDFS-10453.001.patch > > > ReplicationMonitor thread could stuck for long time and loss data with little > probability. Consider the typical scenarioļ¼ > (1) create and close a file with the default replicas(3); > (2) increase replication (to 10) of the file. > (3) delete the file while ReplicationMonitor is scheduling blocks belong to > that file for replications. > if ReplicationMonitor stuck reappeared, NameNode will print log as: > {code:xml} > 2016-04-19 10:20:48,083 WARN > org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy: Failed to > place enough replicas, still in need of 7 to reach 10 > (unavailableStorages=[], storagePolicy=BlockStoragePolicy{HOT:7, > storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]}, > newBlock=false) For more information, please enable DEBUG log level on > org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy > ...... > 2016-04-19 10:21:17,184 WARN > org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy: Failed to > place enough replicas, still in need of 7 to reach 10 > (unavailableStorages=[DISK], storagePolicy=BlockStoragePolicy{HOT:7, > storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]}, > newBlock=false) For more information, please enable DEBUG log level on > org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy > 2016-04-19 10:21:17,184 WARN > org.apache.hadoop.hdfs.protocol.BlockStoragePolicy: Failed to place enough > replicas: expected size is 7 but only 0 storage types can be selected > (replication=10, selected=[], unavailable=[DISK, ARCHIVE], removed=[DISK, > DISK, DISK, DISK, DISK, DISK, DISK], policy=BlockStoragePolicy{HOT:7, > storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]}) > 2016-04-19 10:21:17,184 WARN > org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy: Failed to > place enough replicas, still in need of 7 to reach 10 > (unavailableStorages=[DISK, ARCHIVE], storagePolicy=BlockStoragePolicy{HOT:7, > storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]}, > newBlock=false) All required storage types are unavailable: > unavailableStorages=[DISK, ARCHIVE], storagePolicy=BlockStoragePolicy{HOT:7, > storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]} > {code} > This is because 2 threads (#NameNodeRpcServer and #ReplicationMonitor) > process same block at the same moment. > (1) ReplicationMonitor#computeReplicationWorkForBlocks get blocks to > replicate and leave the global lock. > (2) FSNamesystem#delete invoked to delete blocks then clear the reference in > blocksmap, needReplications, etc. the block's NumBytes will set > NO_ACK(Long.MAX_VALUE) which is used to indicate that the block deletion does > not need explicit ACK from the node. > (3) ReplicationMonitor#computeReplicationWorkForBlocks continue to > chooseTargets for the same blocks and no node will be selected after traverse > whole cluster because no node choice satisfy the goodness criteria > (remaining spaces achieve required size Long.MAX_VALUE). > During of stage#3 ReplicationMonitor stuck for long time, especial in a large > cluster. invalidateBlocks & neededReplications continues to grow and no > consumes. it will loss data at the worst. > This can mostly be avoided by skip chooseTarget for BlockCommand.NO_ACK block > and remove it from neededReplications. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org