[
https://issues.apache.org/jira/browse/HDFS-5496?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13847049#comment-13847049
]
Vinay commented on HDFS-5496:
-----------------------------
I think, block processing will be postponed, not put into invalid queue.
Because of the below change in the patch
{code}+ // postpone making any decision with stale replicas
+ if (numCurrentReplica > expectedReplication
+ && num.replicasOnStaleNodes() > 0) {
+ // If any of the replicas of this block are on nodes that are
+ // considered "stale", then these replicas may in fact have
+ // already been deleted. So, we cannot safely act on the
+ // over-replication until a later point in time, when
+ // the "stale" nodes have block reported.
+ return MisReplicationResult.POSTPONE;
+ }{code}
right?
In that case, better to re-initialize?
> Make replication queue initialization asynchronous
> --------------------------------------------------
>
> Key: HDFS-5496
> URL: https://issues.apache.org/jira/browse/HDFS-5496
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Kihwal Lee
> Assignee: Vinay
> Attachments: HDFS-5496.patch, HDFS-5496.patch
>
>
> Today, initialization of replication queues blocks safe mode exit and certain
> HA state transitions. For a big name space, this can take hundreds of seconds
> with the FSNamesystem write lock held. During this time, important requests
> (e.g. initial block reports, heartbeat, etc) are blocked.
> The effect of delaying the initialization would be not starting replication
> right away, but I think the benefit outweighs. If we make it asynchronous,
> the work per iteration should be limited, so that the lock duration is
> capped.
> If full/incremental block reports and any other requests that modifies block
> state properly performs replication checks while the blocks are scanned and
> the queues populated in background, every block will be processed. (Some may
> be done twice) The replication monitor should run even before all blocks are
> processed.
> This will allow namenode to exit safe mode and start serving immediately even
> with a big name space. It will also reduce the HA failover latency.
--
This message was sent by Atlassian JIRA
(v6.1.4#6159)
