Gopal V created HDFS-6912:
-----------------------------
Summary: HDFS Short-circuit read implementation throws SIGBUS from
misc.Unsafe usage
Key: HDFS-6912
URL: https://issues.apache.org/jira/browse/HDFS-6912
Project: Hadoop HDFS
Issue Type: Bug
Components: caching
Affects Versions: 2.5.0
Environment: HDFS Data node, with 8 gb tmpfs in /dev/shm
Reporter: Gopal V
The short-circuit reader throws SIGBUS errors from Unsafe code and crashes the
JVM when tmpfs on a disk is depleted.
{code}
--------------- T H R E A D ---------------
Current thread (0x00007eff387df800): JavaThread "xxx" daemon [_thread_in_vm,
id=5880, stack(0x00007eff28b93000,0x00007eff28c94000)]
siginfo:si_signo=SIGBUS: si_errno=0, si_code=2 (BUS_ADRERR),
si_addr=0x00007eff3e51d000
{code}
The entire backtrace of the JVM crash is
{code}
Stack: [0x00007eff28b93000,0x00007eff28c94000], sp=0x00007eff28c90a10, free
space=1014k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x88232c] Unsafe_GetLongVolatile+0x6c
j sun.misc.Unsafe.getLongVolatile(Ljava/lang/Object;J)J+0
j org.apache.hadoop.hdfs.ShortCircuitShm$Slot.setFlag(J)V+8
j org.apache.hadoop.hdfs.ShortCircuitShm$Slot.makeValid()V+4
j
org.apache.hadoop.hdfs.ShortCircuitShm.allocAndRegisterSlot(Lorg/apache/hadoop/hdfs/ExtendedBlockId;)Lorg/apache/hadoop/hdfs/ShortCircuitShm$Slot;+70
j
org.apache.hadoop.hdfs.client.DfsClientShmManager$EndpointShmManager.allocSlotFromExistingShm(Lorg/apache/hadoop/hdfs/ExtendedBlockId;)Lorg/apache/hadoop/hdfs/ShortCircuitShm$Slot;+38
j
org.apache.hadoop.hdfs.client.DfsClientShmManager$EndpointShmManager.allocSlot(Lorg/apache/hadoop/hdfs/net/DomainPeer;Lorg/apache/commons/lang/mutable/MutableBoolean;Ljava/lang/String;Lorg/apache/hadoop/hdfs/ExtendedBlockId;)Lorg/apache/hadoop/hdfs/ShortCircuitShm$Slot;+100
j
org.apache.hadoop.hdfs.client.DfsClientShmManager.allocSlot(Lorg/apache/hadoop/hdfs/protocol/DatanodeInfo;Lorg/apache/hadoop/hdfs/net/DomainPeer;Lorg/apache/commons/lang/mutable/MutableBoolean;Lorg/apache/hadoop/hdfs/ExtendedBlockId;Ljava/lang/String;)Lorg/apache/hadoop/hdfs/ShortCircuitShm$Slot;+102
j
org.apache.hadoop.hdfs.client.ShortCircuitCache.allocShmSlot(Lorg/apache/hadoop/hdfs/protocol/DatanodeInfo;Lorg/apache/hadoop/hdfs/net/DomainPeer;Lorg/apache/commons/lang/mutable/MutableBoolean;Lorg/apache/hadoop/hdfs/ExtendedBlockId;Ljava/lang/String;)Lorg/apache/hadoop/hdfs/ShortCircuitShm$Slot;+18
j
org.apache.hadoop.hdfs.BlockReaderFactory.createShortCircuitReplicaInfo()Lorg/apache/hadoop/hdfs/client/ShortCircuitReplicaInfo;+151
j
org.apache.hadoop.hdfs.client.ShortCircuitCache.create(Lorg/apache/hadoop/hdfs/ExtendedBlockId;Lorg/apache/hadoop/hdfs/client/ShortCircuitCache$ShortCircuitReplicaCreator;Lorg/apache/hadoop/util/Waitable;)Lorg/apache/hadoop/hdfs/client/ShortCircuitReplicaInfo;+46
j
org.apache.hadoop.hdfs.client.ShortCircuitCache.fetchOrCreate(Lorg/apache/hadoop/hdfs/ExtendedBlockId;Lorg/apache/hadoop/hdfs/client/ShortCircuitCache$ShortCircuitReplicaCreator;)Lorg/apache/hadoop/hdfs/client/ShortCircuitReplicaInfo;+230
j
org.apache.hadoop.hdfs.BlockReaderFactory.getBlockReaderLocal()Lorg/apache/hadoop/hdfs/BlockReader;+175
j
org.apache.hadoop.hdfs.BlockReaderFactory.build()Lorg/apache/hadoop/hdfs/BlockReader;+87
j
org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(J)Lorg/apache/hadoop/hdfs/protocol/DatanodeInfo;+291
j
org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(Lorg/apache/hadoop/hdfs/DFSInputStream$ReaderStrategy;II)I+83
j org.apache.hadoop.hdfs.DFSInputStream.read([BII)I+15
{code}
This can be easily reproduced by starting the DataNode, filling up tmpfs (dd
if=/dev/zero bs=1M of=/dev/shm/dummy.zero) and running a simple task.
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