Jiandan Yang created HDFS-12177:
------------------------------------
Summary: NameNode exits due to setting BlockPlacementPolicy
loglevel to Debug
Key: HDFS-12177
URL: https://issues.apache.org/jira/browse/HDFS-12177
Project: Hadoop HDFS
Issue Type: Bug
Components: block placement
Affects Versions: 2.8.1
Reporter: Jiandan Yang
NameNode exits because the ReplicationMonitor thread internally throws NPE.
The reason for throwing NPE is that the builder field is not initialized whe do
log.
Solution: before appending it should determine whether the builder is null
{code:java}
if (LOG.isDebugEnabled()) {
builder = debugLoggingBuilder.get();
builder.setLength(0);
builder.append("[");
}
some other codes ...
if (LOG.isDebugEnabled()) {
builder.append("\nNode ").append(NodeBase.getPath(chosenNode))
.append(" [");
}
some other codes ...
if (LOG.isDebugEnabled()) {
builder.append("\n]");
}
{code}
NN exception log is :
{code:java}
java.lang.NullPointerException
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseRandom(BlockPlacementPolicyDefault.java:722)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseRandom(BlockPlacementPolicyDefault.java:689)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseFromNextRack(BlockPlacementPolicyDefault.java:640)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseLocalRack(BlockPlacementPolicyDefault.java:608)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTargetInOrder(BlockPlacementPolicyDefault.java:483)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTarget(BlockPlacementPolicyDefault.java:390)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTarget(BlockPlacementPolicyDefault.java:419)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTarget(BlockPlacementPolicyDefault.java:266)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTarget(BlockPlacementPolicyDefault.java:119)
at
org.apache.hadoop.hdfs.server.blockmanagement.ReplicationWork.chooseTargets(ReplicationWork.java:55)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.computeReplicationWorkForBlocks(BlockManager.java:1532)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.computeReplicationWork(BlockManager.java:1491)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.computeDatanodeWork(BlockManager.java:3768)
at
org.apache.hadoop.hdfs.server.blockmanagement.BlockManager$ReplicationMonitor.run(BlockManager.java:3720)
at java.lang.Thread.run(Thread.java:834)
{code}
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