Ashu Pachauri created HBASE-18137:
-------------------------------------

             Summary: Replication gets stuck for empty WALs
                 Key: HBASE-18137
                 URL: https://issues.apache.org/jira/browse/HBASE-18137
             Project: HBase
          Issue Type: Bug
          Components: Replication
    Affects Versions: 1.3.1
            Reporter: Ashu Pachauri


Replication assumes that only the last WAL of a recovered queue can be empty. 
But, intermittent DFS issues may cause empty WALs being created (without the 
PWAL magic), and a roll of WAL to happen without a regionserver crash. This 
will cause recovered queues to have empty WALs in the middle. This cause 
replication to get stuck:
{code}
TRACE regionserver.ReplicationSource: Opening log <wal_file>
WARN regionserver.ReplicationSource: <peer_cluster_id>-<recovered_queue> Got: 
java.io.EOFException
        at java.io.DataInputStream.readFully(DataInputStream.java:197)
        at java.io.DataInputStream.readFully(DataInputStream.java:169)
        at org.apache.hadoop.io.SequenceFile$Reader.init(SequenceFile.java:1915)
        at 
org.apache.hadoop.io.SequenceFile$Reader.initialize(SequenceFile.java:1880)
        at 
org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1829)
        at 
org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1843)
        at 
org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader$WALReader.<init>(SequenceFileLogReader.java:70)
        at 
org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader.reset(SequenceFileLogReader.java:168)
        at 
org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader.initReader(SequenceFileLogReader.java:177)
        at 
org.apache.hadoop.hbase.regionserver.wal.ReaderBase.init(ReaderBase.java:66)
        at 
org.apache.hadoop.hbase.wal.WALFactory.createReader(WALFactory.java:312)
        at 
org.apache.hadoop.hbase.wal.WALFactory.createReader(WALFactory.java:276)
        at 
org.apache.hadoop.hbase.wal.WALFactory.createReader(WALFactory.java:264)
        at 
org.apache.hadoop.hbase.wal.WALFactory.createReader(WALFactory.java:423)
        at 
org.apache.hadoop.hbase.replication.regionserver.ReplicationWALReaderManager.openReader(ReplicationWALReaderManager.java:70)
        at 
org.apache.hadoop.hbase.replication.regionserver.ReplicationSource$ReplicationSourceWorkerThread.openReader(ReplicationSource.java:830)
        at 
org.apache.hadoop.hbase.replication.regionserver.ReplicationSource$ReplicationSourceWorkerThread.run(ReplicationSource.java:572)
{code}

The WAL in question was completely empty but there were other WALs in the 
recovered queue which were newer and non-empty.



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