[HDFS-9781] FsDatasetImpl#getBlockReports can occasionally throw NullPointerException

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha1
• Fix Version/s: 2.8.0, 3.0.0-alpha2
• Component/s: datanode

Environment

Jenkins

• Hadoop Flags: Reviewed
• Assignee: Manoj Govindassamy
• Reporter: Wei-Chiu Chuang
• Created: 09/Feb/16 00:04
• Updated: 02/Oct/19 17:15
• Resolved: 10/Sep/16 01:26

Description

FsDatasetImpl#getBlockReports occasionally throws NPE. The NPE caused TestFsDatasetImpl#testRemoveVolumeBeingWritten to time out, because the test waits for the call to FsDatasetImpl#getBlockReports to complete without exceptions.

Additionally, the test should be updated to identify an expected exception, using GenericTestUtils.assertExceptionContains()

Exception in thread "Thread-20" java.lang.NullPointerException
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.getBlockReports(FsDatasetImpl.java:1709)
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.TestFsDatasetImpl$1BlockReportThread.run(TestFsDatasetImpl.java:587)
2016-02-08 15:47:30,379 [Thread-21] WARN  impl.TestFsDatasetImpl (TestFsDatasetImpl.java:run(606)) - Exception caught. This should not affect the test
java.io.IOException: Failed to move meta file for ReplicaBeingWritten, blk_0_0, RBW
  getNumBytes()     = 0
  getBytesOnDisk()  = 0
  getVisibleLength()= 0
  getVolume()       = /home/weichiu/hadoop/hadoop-hdfs-project/hadoop-hdfs/target/test/data/Nmi6rYndvr/data0/current
  getBlockFile()    = /home/weichiu/hadoop/hadoop-hdfs-project/hadoop-hdfs/target/test/data/Nmi6rYndvr/data0/current/bpid-0/current/rbw/blk_0
  bytesAcked=0
  bytesOnDisk=0 from /home/weichiu/hadoop/hadoop-hdfs-project/hadoop-hdfs/target/test/data/Nmi6rYndvr/data0/current/bpid-0/current/rbw/blk_0_0.meta to /home/weichiu/hadoop/hadoop-hdfs-project/hadoop-hdfs/target/test/data/Nmi6rYndvr/data0/current/bpid-0/current/finalized/subdir0/subdir0/blk_0_0.meta
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.moveBlockFiles(FsDatasetImpl.java:857)
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.BlockPoolSlice.addFinalizedBlock(BlockPoolSlice.java:295)
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsVolumeImpl.addFinalizedBlock(FsVolumeImpl.java:819)
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.finalizeReplica(FsDatasetImpl.java:1620)
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.finalizeBlock(FsDatasetImpl.java:1601)
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.TestFsDatasetImpl$1ResponderThread.run(TestFsDatasetImpl.java:603)
Caused by: java.io.IOException: renameTo(src=/home/weichiu/hadoop/hadoop-hdfs-project/hadoop-hdfs/target/test/data/Nmi6rYndvr/data0/current/bpid-0/current/rbw/blk_0_0.meta, dst=/home/weichiu/hadoop/hadoop-hdfs-project/hadoop-hdfs/target/test/data/Nmi6rYndvr/data0/current/bpid-0/current/finalized/subdir0/subdir0/blk_0_0.meta) failed.
        at org.apache.hadoop.io.nativeio.NativeIO.renameTo(NativeIO.java:873)
        at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.moveBlockFiles(FsDatasetImpl.java:855)
        ... 5 more
2016-02-08 15:47:34,381 [Thread-19] INFO  impl.FsDatasetImpl (FsVolumeList.java:waitVolumeRemoved(287)) - Volume reference is released.
2016-02-08 15:47:34,384 [Thread-19] INFO  impl.TestFsDatasetImpl (TestFsDatasetImpl.java:testRemoveVolumeBeingWritten(622)) - Volumes removed

Issue Links

• depends upon: HDFS-10830 FsDatasetImpl#removeVolumes crashes with IllegalMonitorStateException when vol being removed is in use
• relates to: HDFS-9701 DN may deadlock when hot-swapping under load
• links to: A failed test