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https://issues.apache.org/jira/browse/HBASE-18955?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16195444#comment-16195444
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Ted Yu commented on HBASE-18955:
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Please include trivial change in hbase-server module for better QA coverage.
> HBase client queries stale hbase:meta location with half-dead RegionServer
> --------------------------------------------------------------------------
>
> Key: HBASE-18955
> URL: https://issues.apache.org/jira/browse/HBASE-18955
> Project: HBase
> Issue Type: Bug
> Components: Client
> Affects Versions: 1.1.12
> Reporter: Josh Elser
> Assignee: Josh Elser
> Priority: Critical
> Fix For: 1.1.13
>
> Attachments: HBASE-18995.001.branch-1.1.patch
>
>
> Have been investigating a case with [~tedyu] where, when a RegionServer
> becomes "hung" (for no specific reason -- not the point), the client becomes
> stuck trying to talk to this RegionServer, never exiting. This was eventually
> tracked down to HBASE-15645. However, in testing the fix, I found that there
> is an additional problem which only affects branch-1.1.
> When the RegionServer in the "half-dead" state is also hosting meta, the
> hbase client (both the one trying to read data, but also the client in the
> Master trying to read meta in SSH) get stuck repeatedly trying to read meta
> from the old location after meta has been reassigned.
> The general test outline goes like this:
> * Start at least 2 regionservers
> * Load some data into a table ({{hbase pe}} is great)
> * Find a region that is hosted by the same RS that is hosting meta
> * {{kill -SIGSTOP}} that RS hosting the user region and meta
> * Issue a {{get}} in the hbase-shell trying to read from that user region
> The expectation is that the ZK lock will expire for the STOP'ed RS, meta will
> be reassigned, then the user regions will be reassigned, then the client will
> get the result of the get without seeing an error (as long as this happens
> within the hbase.client.operation.timeout value, of course).
> We see this happening on HBase 1.2.4 and 1.3.2-SNAPSHOT, but, on
> 1.1.13-SNAPSHOT, the Master gets up to re-assigning meta, but then gets stuck
> trying to read meta from the STOP'ed RS instead of where it re-assigned it.
> Because of this, the regions stay in transition until the master is restarted
> or the STOP'ed RS is CONT'ed. My best guess is that when the RS sees the
> {{SIGCONT}}, it immediately begins stopping which is enough to kick the
> client into refreshing the region location cache.
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