[HADOOP-11969] ThreadLocal initialization in several classes is not thread safe

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 2.8.0, 3.0.0-alpha1
• Component/s: io
• Labels: thread-safety
• Target Version/s: 2.8.0
• Assignee: Sean Busbey
• Reporter: Sean Busbey
• Created: 14/May/15 13:46
• Updated: 30/Aug/16 01:27
• Resolved: 26/May/15 19:41

Description

Right now, the initialization of hte thread local factories for encoder / decoder in Text are not marked final. This means they end up with a static initializer that is not guaranteed to be finished running before the members are visible.

Under heavy contention, this means during initialization some users will get an NPE:

(2015-05-05 08:58:03.974 : solr_server_log.log) 
 org.apache.solr.common.SolrException; null:java.lang.NullPointerException
	at org.apache.hadoop.io.Text.decode(Text.java:406)
	at org.apache.hadoop.io.Text.decode(Text.java:389)
	at org.apache.hadoop.io.Text.toString(Text.java:280)
	at org.apache.hadoop.hdfs.protocolPB.PBHelper.convert(PBHelper.java:764)
	at org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtoUtil.buildBaseHeader(DataTransferProtoUtil.java:81)
	at org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtoUtil.buildClientHeader(DataTransferProtoUtil.java:71)
	at org.apache.hadoop.hdfs.protocol.datatransfer.Sender.readBlock(Sender.java:101)
	at org.apache.hadoop.hdfs.RemoteBlockReader2.newBlockReader(RemoteBlockReader2.java:400)
	at org.apache.hadoop.hdfs.BlockReaderFactory.getRemoteBlockReader(BlockReaderFactory.java:785)
	at org.apache.hadoop.hdfs.BlockReaderFactory.getRemoteBlockReaderFromTcp(BlockReaderFactory.java:663)
	at org.apache.hadoop.hdfs.BlockReaderFactory.build(BlockReaderFactory.java:327)
	at org.apache.hadoop.hdfs.DFSInputStream.actualGetFromOneDataNode(DFSInputStream.java:1027)
	at org.apache.hadoop.hdfs.DFSInputStream.fetchBlockByteRange(DFSInputStream.java:974)
	at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1305)
	at org.apache.hadoop.fs.FSInputStream.readFully(FSInputStream.java:78)
	at org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:107)
... SNIP...