[HDFS-7999] FsDatasetImpl#createTemporary sometimes holds the FSDatasetImpl lock for a very long time

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.6.0
• Fix Version/s: 2.7.0, 2.6.1, 3.0.0-alpha1
• Labels: 2.6.1-candidate
• Target Version/s: 2.7.0
• Assignee: zhouyingchao
• Reporter: zhouyingchao
• Created: 27/Mar/15 11:07
• Updated: 17/Dec/16 08:54
• Resolved: 06/Apr/15 16:11

Description

I'm using 2.6.0 and noticed that sometime DN's heartbeat were delayed for very long time, say more than 100 seconds. I get the jstack twice and looks like they are all blocked (at getStorageReport) by dataset lock, and which is held by a thread that is calling createTemporary, which again is blocked to wait earlier incarnation writer to exit.

The heartbeat thread stack:
java.lang.Thread.State: BLOCKED (on object monitor)
at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsVolumeImpl.getDfsUsed(FsVolumeImpl.java:152)

• waiting to lock <0x00000007b01428c0> (a org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl)
  at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.getStorageReports(FsDatasetImpl.java:144)
• locked <0x00000007b0140ed0> (a java.lang.Object)
  at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.sendHeartBeat(BPServiceActor.java:575)
  at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.offerService(BPServiceActor.java:680)
  at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:850)
  at java.lang.Thread.run(Thread.java:662)

The DataXceiver thread holds the dataset lock:
"DataXceiver for client at XXXXX" daemon prio=10 tid=0x00007f14041e6480 nid=0x52bc in Object.wait() [0x00007f11d78f7000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at java.lang.Thread.join(Thread.java:1194)
locked <0x00000007a33b85d8> (a org.apache.hadoop.util.Daemon)
at org.apache.hadoop.hdfs.server.datanode.ReplicaInPipeline.stopWriter(ReplicaInPipeline.java:183)
at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createTemporary(FsDatasetImpl.java:1231)
locked <0x00000007b01428c0> (a org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl)
at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.createTemporary(FsDatasetImpl.java:114)
at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.<init>(BlockReceiver.java:179)
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:662)

Issue Links

• is related to: HDFS-11260 Slow writer threads are not stopped
• is related to: HDFS-7212 FsDatasetImpl#createTemporary sometimes holds the FSDatasetImpl lock for a very long time
• relates to: HDFS-7060 Avoid taking locks when sending heartbeats from the DataNode