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From "Shalin Shekhar Mangar (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SOLR-6524) Collections left in recovery state after node restart because recovery sleep time increases exponentially between retries
Date Tue, 16 Sep 2014 13:19:35 GMT

    [ https://issues.apache.org/jira/browse/SOLR-6524?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14135406#comment-14135406
] 

Shalin Shekhar Mangar commented on SOLR-6524:
---------------------------------------------

A workaround for people who are affected is to call core reload or collection reload to force
restart the recovery process.

> Collections left in recovery state after node restart because recovery sleep time increases
exponentially between retries
> -------------------------------------------------------------------------------------------------------------------------
>
>                 Key: SOLR-6524
>                 URL: https://issues.apache.org/jira/browse/SOLR-6524
>             Project: Solr
>          Issue Type: Bug
>          Components: SolrCloud
>            Reporter: Shalin Shekhar Mangar
>              Labels: difficulty-medium, impact-medium, workaround-exists
>             Fix For: 4.11
>
>
> The RecoveryStrategy has a retry wait which is exponential in nature. The first time
it waits for 1 second before retrying recovery, then 2 seconds, then 4 seconds and so on.
> This causes problems when running a large number of collections in SolrCloud. We saw
a case where there were 500 collections on 3 nodes (1 shard, 3 replicas) and after a node
is restarted, many collections can't come back up from recovery because:
> # The overseer is slow to process events (I'll create another issue for it)
> # Because the overseer is slow, cluster state updates are delayed and therefore recovery
cannot succeed (WaitForState hangs while waiting to see recovery state on replicas)
> # Because recovery can't succeed immediately, the recovery thread sleeps for larger and
larger amounts of time
> # Even after the whole overseer queue is cleared up, many recovery threads have such
a long sleep that they won't even attempt to recover for many minutes (upto 10 minutes).



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