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https://issues.apache.org/jira/browse/HBASE-25596?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17355899#comment-17355899
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Sandeep Pal commented on HBASE-25596:
-------------------------------------
[~anoop.hbase] Thanks for catching agree that it's a miss. Infact I believe
even the original code was also not correct. The sleep should be reset at the
end anyway even if the batch is null or not.
{code:java}
if (batch == null) {
// either the queue have no WAL to read
// or got no new entries (didn't advance position in WAL)
handleEmptyWALEntryBatch();
entryStream.reset(); // reuse stream
} else {
addBatchToShippingQueue(batch);
}
reset the sleep here <----------{code}
Let me know if you want me to fix it or you are already on it.
> Fix NPE in ReplicationSourceManager as well as avoid permanently unreplicated
> data due to EOFException from WAL
> ---------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-25596
> URL: https://issues.apache.org/jira/browse/HBASE-25596
> Project: HBase
> Issue Type: Bug
> Reporter: Sandeep Pal
> Assignee: Sandeep Pal
> Priority: Critical
> Fix For: 3.0.0-alpha-1, 1.7.0, 2.5.0, 2.4.2
>
>
> There seems to be a major issue with how we handle the EOF exception from
> WALEntryStream.
> Problem:
> When we see EOFException, we try to handle it and remove it from the log
> queue, but we never try to ship the existing batch of entries. *This is a
> permanent data loss in replication.*
>
> Secondly, we do not stop the reader on encountering the EOFException and thus
> if EOFException was on the last WAL, we still try to process the WALEntry
> stream and ship the empty batch with lastWALPath set to null. This is the
> reason of NPE as below which *crash* the region server.
> {code:java}
> 2021-02-16 15:33:21,293 ERROR [,60020,1613262147968]
> regionserver.ReplicationSource - Unexpected exception in
> ReplicationSourceWorkerThread,
> currentPath=nulljava.lang.NullPointerExceptionat
> org.apache.hadoop.hbase.replication.regionserver.ReplicationSourceManager.logPositionAndCleanOldLogs(ReplicationSourceManager.java:193)at
>
> org.apache.hadoop.hbase.replication.regionserver.ReplicationSource$ReplicationSourceShipperThread.updateLogPosition(ReplicationSource.java:831)at
>
> org.apache.hadoop.hbase.replication.regionserver.ReplicationSource$ReplicationSourceShipperThread.shipEdits(ReplicationSource.java:746)at
>
> org.apache.hadoop.hbase.replication.regionserver.ReplicationSource$ReplicationSourceShipperThread.run(ReplicationSource.java:650)2021-02-16
> 15:33:21,294 INFO [,60020,1613262147968] regionserver.HRegionServer -
> STOPPED: Unexpected exception in ReplicationSourceWorkerThread
> {code}
>
>
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