A Client File Fails to Be Closed After Data Writing

Symptom

A client file fails to be closed after data is written to the file. A message is displayed indicating that the data block does not have enough replicas.

Client log:

2015-05-27 19:00:52.811 [pool-2-thread-3] ERROR: /tsp/nedata/collect/UGW/ugwufdr/20150527/10/6_20150527105000_20150527105500_SR5S14_1432723806338_128_11.pkg.tmp1432723806338 close hdfs sequence file fail (SequenceFileInfoChannel.java:444)
java.io.IOException: Unable to close file because the last block does not have enough number of replicas.
at org.apache.hadoop.hdfs.DFSOutputStream.completeFile(DFSOutputStream.java:2160)
at org.apache.hadoop.hdfs.DFSOutputStream.close(DFSOutputStream.java:2128)
at org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:70)
at org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:103)
at com.xxx.pai.collect2.stream.SequenceFileInfoChannel.close(SequenceFileInfoChannel.java:433)
at com.xxx.pai.collect2.stream.SequenceFileWriterToolChannel$FileCloseTask.call(SequenceFileWriterToolChannel.java:804)
at com.xxx.pai.collect2.stream.SequenceFileWriterToolChannel$FileCloseTask.call(SequenceFileWriterToolChannel.java:792)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)

Cause Analysis

1. The HDFS client starts to write blocks.

   For example, the HDFS client starts to write /20150527/10/6_20150527105000_20150527105500_SR5S14_1432723806338_128_11.pkg.tmp1432723806338 at 2015-05-27 18:50:24,232. The allocated block is blk_1099105501_25370893:

   2015-05-27 18:50:24,232 | INFO  | IPC Server handler 30 on 25000 | BLOCK* allocateBlock: /20150527/10/6_20150527105000_20150527105500_SR5S14_1432723806338_128_11.pkg.tmp1432723806338. BP-1803470917-192.168.57.33-1428597734132 blk_1099105501_25370893{blockUCState=UNDER_CONSTRUCTION, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-b2d7b7d0-f410-4958-8eba-6deecbca2f87:NORMAL|RBW], ReplicaUnderConstruction[[DISK]DS-76bd80e7-ad58-49c6-bf2c-03f91caf750f:NORMAL|RBW]]} | org.apache.hadoop.hdfs.server.namenode.FSNamesystem.saveAllocatedBlock(FSNamesystem.java:3166)

2. After the writing is complete, the HDFS client invokes fsync:

   2015-05-27 19:00:22,717 | INFO  | IPC Server handler 22 on 25000 | BLOCK* fsync: 20150527/10/6_20150527105000_20150527105500_SR5S14_1432723806338_128_11.pkg.tmp1432723806338 for DFSClient_NONMAPREDUCE_-120525246_15 | org.apache.hadoop.hdfs.server.namenode.FSNamesystem.fsync(FSNamesystem.java:3805)

3. The HDFS client invokes close to close the file. After receiving the close request from the client, the NameNode uses the checkFileProgress function to check the completion status of the last block and closes the file only when enough DataNodes report that the last block is complete:

   2015-05-27 19:00:27,603 | INFO  | IPC Server handler 44 on 25000 | BLOCK* checkFileProgress: blk_1099105501_25370893{blockUCState=COMMITTED, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-ef5fd3c9-5088-4813-ae9a-34a0714ec3a3:NORMAL|RBW], ReplicaUnderConstruction[[DISK]DS-f863e30f-ce5b-48cc-9cca-72f64c558adc:NORMAL|RBW]]} has not reached minimal replication 1 | org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkFileProgress(FSNamesystem.java:3197)
   2015-05-27 19:00:28,005 | INFO  | IPC Server handler 45 on 25000 | BLOCK* checkFileProgress: blk_1099105501_25370893{blockUCState=COMMITTED, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-ef5fd3c9-5088-4813-ae9a-34a0714ec3a3:NORMAL|RBW], ReplicaUnderConstruction[[DISK]DS-f863e30f-ce5b-48cc-9cca-72f64c558adc:NORMAL|RBW]]} has not reached minimal replication 1 | org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkFileProgress(FSNamesystem.java:3197)
   2015-05-27 19:00:28,806 | INFO  | IPC Server handler 63 on 25000 | BLOCK* checkFileProgress: blk_1099105501_25370893{blockUCState=COMMITTED, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-ef5fd3c9-5088-4813-ae9a-34a0714ec3a3:NORMAL|RBW], ReplicaUnderConstruction[[DISK]DS-f863e30f-ce5b-48cc-9cca-72f64c558adc:NORMAL|RBW]]} has not reached minimal replication 1 | org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkFileProgress(FSNamesystem.java:3197)
   2015-05-27 19:00:30,408 | INFO  | IPC Server handler 43 on 25000 | BLOCK* checkFileProgress: blk_1099105501_25370893{blockUCState=COMMITTED, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-ef5fd3c9-5088-4813-ae9a-34a0714ec3a3:NORMAL|RBW], ReplicaUnderConstruction[[DISK]DS-f863e30f-ce5b-48cc-9cca-72f64c558adc:NORMAL|RBW]]} has not reached minimal replication 1 | org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkFileProgress(FSNamesystem.java:3197)
   2015-05-27 19:00:33,610 | INFO  | IPC Server handler 37 on 25000 | BLOCK* checkFileProgress: blk_1099105501_25370893{blockUCState=COMMITTED, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-ef5fd3c9-5088-4813-ae9a-34a0714ec3a3:NORMAL|RBW], ReplicaUnderConstruction[[DISK]DS-f863e30f-ce5b-48cc-9cca-72f64c558adc:NORMAL|RBW]]} has not reached minimal replication 1 | org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkFileProgress(FSNamesystem.java:3197)
   2015-05-27 19:00:40,011 | INFO  | IPC Server handler 37 on 25000 | BLOCK* checkFileProgress: blk_1099105501_25370893{blockUCState=COMMITTED, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-ef5fd3c9-5088-4813-ae9a-34a0714ec3a3:NORMAL|RBW], ReplicaUnderConstruction[[DISK]DS-f863e30f-ce5b-48cc-9cca-72f64c558adc:NORMAL|RBW]]} has not reached minimal replication 1 | org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkFileProgress(FSNamesystem.java:3197)

4. The NameNode prints CheckFileProgress multiple times because the HDFS client retries to close the file for several times. The file closing fails because the block status is not complete. The number of retries is determined by the dfs.client.block.write.locateFollowingBlock.retries parameter. The default value is 5. Therefore, CheckFileProgress is printed six times in the NameNode log.
5. After 0.5 seconds, the DataNodes report that the block has been successfully written.

   2015-05-27 19:00:40,608 | INFO  | IPC Server handler 60 on 25000 | BLOCK* addStoredBlock: blockMap updated: 192.168.10.21:25009 is added to blk_1099105501_25370893{blockUCState=COMMITTED, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-ef5fd3c9-5088-4813-ae9a-34a0714ec3a3:NORMAL|RBW], ReplicaUnderConstruction[[DISK]DS-f863e30f-ce5b-48cc-9cca-72f64c558adc:NORMAL|RBW]]} size 11837530 | org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.logAddStoredBlock(BlockManager.java:2393)
   2015-05-27 19:00:48,297 | INFO  | IPC Server handler 37 on 25000 | BLOCK* addStoredBlock: blockMap updated: 192.168.10.10:25009 is added to blk_1099105501_25370893 size 11837530 | org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.logAddStoredBlock(BlockManager.java:2393)

6. The block write success notification is delayed because of network bottlenecks or CPU bottlenecks.
7. If close is invoked again or the number of file closing retries increases, a closing success message will be displayed. You are advised to increase the value of dfs.client.block.write.locateFollowingBlock.retries. The default parameter value is 5 and retry intervals are 400 ms, 800 ms, 1600 ms, 3200 ms, 6400 ms, and 12800 ms. Therefore, the result of the close function can be returned after a maximum of 25.2 seconds.

Solution

1. Solution:

   Set the value of dfs.client.block.write.locateFollowingBlock.retries to 6. The retry intervals are 400 ms, 800 ms, 1600 ms, 3200 ms, 6400 ms, and 12800 ms. Therefore, the result of the close function can be returned after a maximum of 50.8 seconds.

Remarks

Generally, this fault occurs when the cluster workload is heavy. Adjusting the parameter can only temporarily avoid the fault. You are advised to reduce the cluster workload, for example, do not allocate all CPU resources to MapReduce.