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Posted to hdfs-issues@hadoop.apache.org by "Stephen O'Donnell (JIRA)" <ji...@apache.org> on 2019/07/10 15:15:00 UTC

[jira] [Updated] (HDFS-14642) processMisReplicatedBlocks does not return correct processed count

     [ https://issues.apache.org/jira/browse/HDFS-14642?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Stephen O'Donnell updated HDFS-14642:
-------------------------------------
    Attachment: HDFS-14642.001.patch

> processMisReplicatedBlocks does not return correct processed count
> ------------------------------------------------------------------
>
>                 Key: HDFS-14642
>                 URL: https://issues.apache.org/jira/browse/HDFS-14642
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 3.2.0
>            Reporter: Stephen O'Donnell
>            Assignee: Stephen O'Donnell
>            Priority: Major
>         Attachments: HDFS-14642.001.patch
>
>
> HDFS-14053 introduced a method "processMisReplicatedBlocks" to the blockManager, and it is used by fsck to schedule mis-replicated blocks for replication.
> The method should return a the number of blocks it processed, but it always returns zero as "processed" is never incremented in the method.
> It should also drop and re-take the write lock every "numBlocksPerIteration" but as processed is never incremented, it will never drop and re-take the write lock, giving potential for holding the write lock for a long time.
> {code:java}
> public int processMisReplicatedBlocks(List<BlockInfo> blocks) {
>   int processed = 0;
>   Iterator<BlockInfo> iter = blocks.iterator();
>   try {
>     while (isPopulatingReplQueues() && namesystem.isRunning()
>             && !Thread.currentThread().isInterrupted()
>             && iter.hasNext()) {
>       int limit = processed + numBlocksPerIteration;
>       namesystem.writeLockInterruptibly();
>       try {
>         while (iter.hasNext() && processed < limit) {
>           BlockInfo blk = iter.next();
>           MisReplicationResult r = processMisReplicatedBlock(blk);
>           LOG.debug("BLOCK* processMisReplicatedBlocks: " +
>                   "Re-scanned block {}, result is {}", blk, r);
>         }
>       } finally {
>         namesystem.writeUnlock();
>       }
>     }
>   } catch (InterruptedException ex) {
>     LOG.info("Caught InterruptedException while scheduling replication work" +
>             " for mis-replicated blocks");
>     Thread.currentThread().interrupt();
>   }
>   return processed;
> }{code}
> Due to this, fsck causes a warning to be logged in the NN for every mis-replicated file it schedules replication for, as it checks the processed count:
> {code:java}
> 2019-07-10 15:46:14,790 WARN namenode.NameNode: Fsck: Block manager is able to process only 0 mis-replicated blocks (Total count : 1 ) for path /...{code}



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