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Posted to hdfs-issues@hadoop.apache.org by "Jingcheng Du (JIRA)" <ji...@apache.org> on 2016/03/14 08:38:33 UTC
[jira] [Updated] (HDFS-9668) Many long-time BLOCKED threads on
FsDatasetImpl in a tiered storage test
[ https://issues.apache.org/jira/browse/HDFS-9668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jingcheng Du updated HDFS-9668:
-------------------------------
Attachment: HDFS-9668-2.patch
Upload a new patch (V2) to address the comments. Thanks.
> Many long-time BLOCKED threads on FsDatasetImpl in a tiered storage test
> ------------------------------------------------------------------------
>
> Key: HDFS-9668
> URL: https://issues.apache.org/jira/browse/HDFS-9668
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Reporter: Jingcheng Du
> Assignee: Jingcheng Du
> Attachments: HDFS-9668-1.patch, HDFS-9668-2.patch, execution_time.png
>
>
> During the HBase test on a tiered storage of HDFS (WAL is stored in SSD/RAMDISK, and all other files are stored in HDD), we observe many long-time BLOCKED threads on FsDatasetImpl in DataNode. The following is part of the jstack result:
> {noformat}
> "DataXceiver for client DFSClient_NONMAPREDUCE_-1626037897_1 at /192.168.50.16:48521 [Receiving block BP-1042877462-192.168.50.13-1446173170517:blk_1073779272_40852]" - Thread t@93336
> java.lang.Thread.State: BLOCKED
> at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createRbw(FsDatasetImpl.java:1111)
> - waiting to lock <18324c9> (a org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl) owned by "DataXceiver for client DFSClient_NONMAPREDUCE_-1626037897_1 at /192.168.50.16:48520 [Receiving block BP-1042877462-192.168.50.13-1446173170517:blk_1073779271_40851]" t@93335
> at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createRbw(FsDatasetImpl.java:113)
> at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.<init>(BlockReceiver.java:183)
> at org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:615)
> at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opWriteBlock(Receiver.java:137)
> at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:74)
> at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:235)
> at java.lang.Thread.run(Thread.java:745)
> Locked ownable synchronizers:
> - None
>
> "DataXceiver for client DFSClient_NONMAPREDUCE_-1626037897_1 at /192.168.50.16:48520 [Receiving block BP-1042877462-192.168.50.13-1446173170517:blk_1073779271_40851]" - Thread t@93335
> java.lang.Thread.State: RUNNABLE
> at java.io.UnixFileSystem.createFileExclusively(Native Method)
> at java.io.File.createNewFile(File.java:1012)
> at org.apache.hadoop.hdfs.server.datanode.DatanodeUtil.createTmpFile(DatanodeUtil.java:66)
> at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.BlockPoolSlice.createRbwFile(BlockPoolSlice.java:271)
> at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsVolumeImpl.createRbwFile(FsVolumeImpl.java:286)
> at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createRbw(FsDatasetImpl.java:1140)
> - locked <18324c9> (a org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl)
> at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createRbw(FsDatasetImpl.java:113)
> at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.<init>(BlockReceiver.java:183)
> at org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:615)
> at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opWriteBlock(Receiver.java:137)
> at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:74)
> at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:235)
> at java.lang.Thread.run(Thread.java:745)
> Locked ownable synchronizers:
> - None
> {noformat}
> We measured the execution of some operations in FsDatasetImpl during the test. Here following is the result.
> !execution_time.png!
> The operations of finalizeBlock, addBlock and createRbw on HDD in a heavy load take a really long time.
> It means one slow operation of finalizeBlock, addBlock and createRbw in a slow storage can block all the other same operations in the same DataNode, especially in HBase when many wal/flusher/compactor are configured.
> We need a finer grained lock mechanism in a new FsDatasetImpl implementation and users can choose the implementation by configuring "dfs.datanode.fsdataset.factory" in DataNode.
> We can implement the lock by either storage level or block-level.
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