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Date: Thu, 28 Mar 2013 20:35:16 +0000 (UTC)
From: "Jean-Daniel Cryans (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12639494.1364429873688.71744.1364502916315@arcas>
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Subject: [jira] [Commented] (HBASE-8207) Replication could have data loss
 when machine name contains hyphen "-"
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    [ https://issues.apache.org/jira/browse/HBASE-8207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13616623#comment-13616623 ] 

Jean-Daniel Cryans commented on HBASE-8207:
-------------------------------------------

Mmm sorry about this one, guys. I guess that's what happens when you test only in one environment.

bq. 1) When replication is waiting for log splitting complete, there is no sleep in between so we keep hitting hdfs name node 

Since the HLog is always "somewhere", AFAIK we don't wait for log splitting to finish.

About the patch, it seems that the "extract dead servers" logic should itself be extracted into its own method.
                
> Replication could have data loss when machine name contains hyphen "-"
> ----------------------------------------------------------------------
>
>                 Key: HBASE-8207
>                 URL: https://issues.apache.org/jira/browse/HBASE-8207
>             Project: HBase
>          Issue Type: Bug
>          Components: Replication
>    Affects Versions: 0.95.0, 0.94.6
>            Reporter: Jeffrey Zhong
>            Assignee: Jeffrey Zhong
>            Priority: Critical
>             Fix For: 0.95.0, 0.98.0, 0.94.7
>
>         Attachments: failed.txt, hbase-8207.patch, HBASE-8212-94.patch
>
>
> In the recent test case TestReplication* failures, I'm finally able to find the cause(or one of causes) for its intermittent failures.
> When a machine name contains "-", it breaks the function ReplicationSource.checkIfQueueRecovered. It causes the following issue:
> deadRegionServers list is way off so that replication doesn't wait for log splitting finish for a wal file and move on to the next one(data loss)
> You can see that replication use those weird paths constructed from deadRegionServers to check a file existence
> {code}
> 2013-03-26 21:26:51,385 INFO  [ReplicationExecutor-0.replicationSource,2-ip-10-197-0-156.us-west-1.compute.internal,52170,1364333181125] regionserver.ReplicationSource(524): Possible location hdfs://localhost:52882/user/ec2-user/hbase/.logs/1.compute.internal,52170,1364333181125/ip-10-197-0-156.us-west-1.compute.internal%252C52170%252C1364333181125.1364333199540
> 2013-03-26 21:26:51,386 INFO  [ReplicationExecutor-0.replicationSource,2-ip-10-197-0-156.us-west-1.compute.internal,52170,1364333181125] regionserver.ReplicationSource(524): Possible location hdfs://localhost:52882/user/ec2-user/hbase/.logs/1.compute.internal,52170,1364333181125-splitting/ip-10-197-0-156.us-west-1.compute.internal%252C52170%252C1364333181125.1364333199540
> 2013-03-26 21:26:51,387 INFO  [ReplicationExecutor-0.replicationSource,2-ip-10-197-0-156.us-west-1.compute.internal,52170,1364333181125] regionserver.ReplicationSource(524): Possible location hdfs://localhost:52882/user/ec2-user/hbase/.logs/west/ip-10-197-0-156.us-west-1.compute.internal%252C52170%252C1364333181125.1364333199540
> 2013-03-26 21:26:51,389 INFO  [ReplicationExecutor-0.replicationSource,2-ip-10-197-0-156.us-west-1.compute.internal,52170,1364333181125] regionserver.ReplicationSource(524): Possible location hdfs://localhost:52882/user/ec2-user/hbase/.logs/west-splitting/ip-10-197-0-156.us-west-1.compute.internal%252C52170%252C1364333181125.1364333199540
> 2013-03-26 21:26:51,391 INFO  [ReplicationExecutor-0.replicationSource,2-ip-10-197-0-156.us-west-1.compute.internal,52170,1364333181125] regionserver.ReplicationSource(524): Possible location hdfs://localhost:52882/user/ec2-user/hbase/.logs/156.us/ip-10-197-0-156.us-west-1.compute.internal%252C52170%252C1364333181125.1364333199540
> 2013-03-26 21:26:51,394 INFO  [ReplicationExecutor-0.replicationSource,2-ip-10-197-0-156.us-west-1.compute.internal,52170,1364333181125] regionserver.ReplicationSource(524): Possible location hdfs://localhost:52882/user/ec2-user/hbase/.logs/156.us-splitting/ip-10-197-0-156.us-west-1.compute.internal%252C52170%252C1364333181125.1364333199540
> 2013-03-26 21:26:51,396 INFO  [ReplicationExecutor-0.replicationSource,2-ip-10-197-0-156.us-west-1.compute.internal,52170,1364333181125] regionserver.ReplicationSource(524): Possible location hdfs://localhost:52882/user/ec2-user/hbase/.logs/0/ip-10-197-0-156.us-west-1.compute.internal%252C52170%252C1364333181125.1364333199540
> 2013-03-26 21:26:51,398 INFO  [ReplicationExecutor-0.replicationSource,2-ip-10-197-0-156.us-west-1.compute.internal,52170,1364333181125] regionserver.ReplicationSource(524): Possible location hdfs://localhost:52882/user/ec2-user/hbase/.logs/0-splitting/ip-10-197-0-156.us-west-1.compute.internal%252C52170%252C1364333181125.1364333199540
> {code}
> This happened in the recent test failure in http://54.241.6.143/job/HBase-0.94/org.apache.hbase$hbase/21/testReport/junit/org.apache.hadoop.hbase.replication/TestReplicationQueueFailover/queueFailover/?auto_refresh=false
> Search for 
> {code}
> File does not exist: hdfs://localhost:52882/user/ec2-user/hbase/.oldlogs/ip-10-197-0-156.us-west-1.compute.internal%2C52170%2C1364333181125.1364333199540
> {code}
> After 10 times retries, replication source gave up and move on to the next file. Data loss happens. 
> Since lots of EC2 machine names contain "-" including our Jenkin servers, this is a high impact issue.

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