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John Zhuge commented on HDFS-7060: ---------------------------------- If we assume dataset lock protects {{bpSlices}}. The following functions access {{bpSlices}} but they and their callers do NOT lock dataset. Did I miss anything? Is this a bug? {code} FsVolumeImpl#addBlockPool (this is a write access to bpSlices) FsVolumeImpl#addBlockPool FsDatasetImpl#addVolume FsVolumeImpl#getBlockPoolUsed FsVolumeList#getBlockPoolUsed FsDatasetImpl#getBlockPoolUsed FsVolumeImpl#getBlockPoolSlice (too many callers, hard to track down !) FsVolumeImpl#getBlockPoolList DirectoryScanner.ReportCompiler#call FsVolumeImpl#checkDirs FsVolumeImpl#checkDirs FsDatasetImpl#checkDataDir ... {code} A few suggestions regarding lock usage: * All locks including intrinsic locks should include docs that clearly state what resources they protect. * Locks should be used in the classes they are defined. Very hard to reason if their usages are scattered around. If we want to protect {{bpSlices}} with lock, can we just use {{bpSlices}} intrinsic lock instead of dataset lock? > Avoid taking locks when sending heartbeats from the DataNode > ------------------------------------------------------------ > > Key: HDFS-7060 > URL: https://issues.apache.org/jira/browse/HDFS-7060 > Project: Hadoop HDFS > Issue Type: Improvement > Reporter: Haohui Mai > Assignee: Xinwei Qin > Labels: BB2015-05-TBR > Attachments: HDFS-7060-002.patch, HDFS-7060.000.patch, > HDFS-7060.001.patch > > > We're seeing the heartbeat is blocked by the monitor of {{FsDatasetImpl}} > when the DN is under heavy load of writes: > {noformat} > java.lang.Thread.State: BLOCKED (on object monitor) > at > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsVolumeImpl.getDfsUsed(FsVolumeImpl.java:115) > - waiting to lock <0x0000000780304fb8> (a > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl) > at > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.getStorageReports(FsDatasetImpl.java:91) > - locked <0x0000000780612fd8> (a java.lang.Object) > at > org.apache.hadoop.hdfs.server.datanode.BPServiceActor.sendHeartBeat(BPServiceActor.java:563) > at > org.apache.hadoop.hdfs.server.datanode.BPServiceActor.offerService(BPServiceActor.java:668) > at > org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:827) > at java.lang.Thread.run(Thread.java:744) > java.lang.Thread.State: BLOCKED (on object monitor) > at > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createRbw(FsDatasetImpl.java:743) > - waiting to lock <0x0000000780304fb8> (a > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl) > at > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createRbw(FsDatasetImpl.java:60) > at > org.apache.hadoop.hdfs.server.datanode.BlockReceiver.<init>(BlockReceiver.java:169) > at > org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:621) > at > org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opWriteBlock(Receiver.java:124) > at > org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:71) > at > org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:232) > at java.lang.Thread.run(Thread.java:744) > java.lang.Thread.State: RUNNABLE > at java.io.UnixFileSystem.createFileExclusively(Native Method) > at java.io.File.createNewFile(File.java:1006) > at > org.apache.hadoop.hdfs.server.datanode.DatanodeUtil.createTmpFile(DatanodeUtil.java:59) > at > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.BlockPoolSlice.createRbwFile(BlockPoolSlice.java:244) > at > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsVolumeImpl.createRbwFile(FsVolumeImpl.java:195) > at > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createRbw(FsDatasetImpl.java:753) > - locked <0x0000000780304fb8> (a > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl) > at > org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createRbw(FsDatasetImpl.java:60) > at > org.apache.hadoop.hdfs.server.datanode.BlockReceiver.<init>(BlockReceiver.java:169) > at > org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:621) > at > org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opWriteBlock(Receiver.java:124) > at > org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:71) > at > org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:232) > at java.lang.Thread.run(Thread.java:744) > {noformat} -- This message was sent by Atlassian JIRA (v6.3.4#6332)