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https://issues.apache.org/jira/browse/HDFS-12043?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chen Liang updated HDFS-12043:
------------------------------
Attachment: HDFS-12043.002.patch
Thanks [~arpitagarwal] for the comments! Post v002 patch.
The other comments are addressed. Regarding the {{if (pendingNum > 0)}} branch,
my understanding is that this means there are unfinished replication going on,
not necessarily failed re-replication. It could still finish successfully, also
it may timeout and counted by the other timeout counter. What do you think?
Also in v002 patch, changed the place of incrementing timeout re-replication to
the place where it gets detected in {{PendingReconstructionBlocks}}'s thread.
v001 patch actually delays the increment by calling in {{BlockManager}}'s
thread.
> Add counters for block re-replication
> -------------------------------------
>
> Key: HDFS-12043
> URL: https://issues.apache.org/jira/browse/HDFS-12043
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Chen Liang
> Assignee: Chen Liang
> Attachments: HDFS-12043.001.patch, HDFS-12043.002.patch
>
>
> We occasionally see that the under-replicated block count is not going down
> quickly enough. We've made at least one fix to speed up block replications
> (HDFS-9205) but we need better insight into the current state and activity of
> the block re-replication logic. For example, we need to understand whether is
> it because re-replication is not making forward progress at all, or is it
> because new under-replicated blocks are being added faster.
> We should include additional metrics:
> # Cumulative number of blocks that were successfully replicated.
> # Cumulative number of re-replications that timed out.
> # Cumulative number of blocks that were dequeued for re-replication but not
> scheduled e.g. because they were invalid, or under-construction or
> replication was postponed.
>
> The growth rate of of the above metrics will make it clear whether block
> replication is making forward progress and if not then provide potential
> clues about why it is stalled.
> Thanks [~arpitagarwal] for the offline discussions.
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