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Posted to hdfs-dev@hadoop.apache.org by "Bogdan Raducanu (JIRA)" <ji...@apache.org> on 2016/03/04 22:52:40 UTC

[jira] [Created] (HDFS-9909) Can't read file after hdfs restart

Bogdan Raducanu created HDFS-9909:
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             Summary: Can't read file after hdfs restart
                 Key: HDFS-9909
                 URL: https://issues.apache.org/jira/browse/HDFS-9909
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: hdfs-client
    Affects Versions: 2.7.1
            Reporter: Bogdan Raducanu


If HDFS is restarted while a file is open for writing then new clients can't read that file until the hard lease limit expires and block recovery starts.

Scenario:
1. write to file, call hflush
2. without closing the file, restart hdfs 
3. after hdfs is back up, try to open file from reading from a new client

Repro attached.

Thoughts:
* As far as I can tell this happens because the last block is RWR and getReplicaVisibleLength returns -1 for this. The recovery starts after hard lease limit expires (so file is readable only after 1 hour).
* one can call recoverLease which will start the lease recovery sooner, BUT, how can one know when to call this? The exception thrown is IOException which can happen for other reasons.

I think a reasonable solution would be to return a specialized exception (similar to AlreadyBeingCreatedException when trying to write to open file).



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