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Date: Wed, 30 Jul 2014 20:12:41 +0000 (UTC)
From: "Ted Yu (JIRA)" <jira@apache.org>
To: dev@hbase.apache.org
Message-ID: <JIRA.12730899.1406751112868.79783.1406751161600@arcas>
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Subject: [jira] [Created] (HBASE-11620) Propagate decoder exception to
 HLogSplitter so that loss of data is avoided
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Ted Yu created HBASE-11620:
------------------------------

             Summary: Propagate decoder exception to HLogSplitter so that loss of data is avoided
                 Key: HBASE-11620
                 URL: https://issues.apache.org/jira/browse/HBASE-11620
             Project: HBase
          Issue Type: Bug
            Reporter: Ted Yu
            Priority: Critical


Reported by Kiran in this thread: "HBase file encryption, inconsistencies observed and data loss"

After step 4 ( i.e disabling of WAL encryption, removing SecureProtobufReader/Writer and restart), read of encrypted WAL fails mainly due to EOF exception at Basedecoder. This is not considered as error and these WAL are being moved to /oldWALs.

Following is observed in log files:
{code}
2014-07-30 19:44:29,254 INFO  [RS_LOG_REPLAY_OPS-HOST-16:15264-1] wal.HLogSplitter: Splitting hlog: hdfs://HOST-16:18020/hbase/WALs/HOST-16,15264,1406725441997-splitting/HOST-16%2C15264%2C1406725441997.1406725444017, length=172
2014-07-30 19:44:29,254 INFO  [RS_LOG_REPLAY_OPS-HOST-16:15264-1] wal.HLogSplitter: DistributedLogReplay = false
2014-07-30 19:44:29,313 INFO  [RS_LOG_REPLAY_OPS-HOST-16:15264-1] util.FSHDFSUtils: Recovering lease on dfs file hdfs://HOST-16:18020/hbase/WALs/HOST-16,15264,1406725441997-splitting/HOST-16%2C15264%2C1406725441997.1406725444017
2014-07-30 19:44:29,315 INFO  [RS_LOG_REPLAY_OPS-HOST-16:15264-1] util.FSHDFSUtils: recoverLease=true, attempt=0 on file=hdfs://HOST-16:18020/hbase/WALs/HOST-16,15264,1406725441997-splitting/HOST-16%2C15264%2C1406725441997.1406725444017 after 1ms
2014-07-30 19:44:29,429 DEBUG [RS_LOG_REPLAY_OPS-HOST-16:15264-1-Writer-0] wal.HLogSplitter: Writer thread Thread[RS_LOG_REPLAY_OPS-HOST-16:15264-1-Writer-0,5,main]: starting
2014-07-30 19:44:29,429 DEBUG [RS_LOG_REPLAY_OPS-HOST-16:15264-1-Writer-1] wal.HLogSplitter: Writer thread Thread[RS_LOG_REPLAY_OPS-HOST-16:15264-1-Writer-1,5,main]: starting
2014-07-30 19:44:29,430 DEBUG [RS_LOG_REPLAY_OPS-HOST-16:15264-1-Writer-2] wal.HLogSplitter: Writer thread Thread[RS_LOG_REPLAY_OPS-HOST-16:15264-1-Writer-2,5,main]: starting
2014-07-30 19:44:29,591 ERROR [RS_LOG_REPLAY_OPS-HOST-16:15264-1] codec.BaseDecoder: Partial cell read caused by EOF: java.io.IOException: Premature EOF from inputStream
2014-07-30 19:44:29,592 INFO  [RS_LOG_REPLAY_OPS-HOST-16:15264-1] wal.HLogSplitter: Finishing writing output logs and closing down.
2014-07-30 19:44:29,592 INFO  [RS_LOG_REPLAY_OPS-HOST-16:15264-1] wal.HLogSplitter: Waiting for split writer threads to finish
2014-07-30 19:44:29,592 INFO  [RS_LOG_REPLAY_OPS-HOST-16:15264-1] wal.HLogSplitter: Split writers finished
2014-07-30 19:44:29,592 INFO  [RS_LOG_REPLAY_OPS-HOST-16:15264-1] wal.HLogSplitter: Processed 0 edits across 0 regions; log file=hdfs://HOST-16:18020/hbase/WALs/HOST-16,15264,1406725441997-splitting/HOST-16%2C15264%2C1406725441997.1406725444017 is corrupted = false progress failed = false
{code}
To fix this, we need to propagate EOF exception to HLogSplitter. Any suggestions on the fix?

-------- (end of quote from Kiran)

In BaseDecoder#rethrowEofException() :
{code}
    if (!isEof) throw ioEx;
    LOG.error("Partial cell read caused by EOF: " + ioEx);
    EOFException eofEx = new EOFException("Partial cell read");
    eofEx.initCause(ioEx);
    throw eofEx;
{code}
throwing EOFException would not propagate the "Partial cell read" condition to HLogSplitter which doesn't treat EOFException as an error.

I think a new exception type (DecoderException e.g.) should be used above.


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