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https://issues.apache.org/jira/browse/HBASE-12028?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14142123#comment-14142123
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Andrew Purtell commented on HBASE-12028:
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Aborting the RS if a handler thread terminates due to an unhandled throwable
seems like a good idea. Who knows what state the thread left things in, what
operation is unclosed, what lock is still held, what counter was not
decremented. The RS could be a ticking bomb.
> Abort the RegionServer, when one of it's handler threads die
> ------------------------------------------------------------
>
> Key: HBASE-12028
> URL: https://issues.apache.org/jira/browse/HBASE-12028
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Reporter: Sudarshan Kadambi
>
> Over in HBase-11813, a user identified an issue where in all the RPC handler
> threads would exit with StackOverflow errors due to an unchecked
> recursion-terminating condition. Our clusters demonstrated the same trace.
> While the patch posted for HBASE-11813 got our clusters to be merry again,
> the breakdown surfaced some larger issues.
> When the RegionServer had all it's RPC handler threads dead, it continued to
> have regions assigned it. Clearly, it wouldn't be able to serve reads and
> writes on those regions. A second issue was that when a user tried to disable
> or drop a table, the master would try to communicate to the regionserver for
> region unassignment. Since the same handler threads seem to be used for
> master <-> RS communication as well, the master ended up hanging on the RS
> indefinitely. Eventually, the master stopped responding to all table
> meta-operations.
> A handler thread should never exit, and if it does, it seems like the more
> prudent thing to do would be for the RS to abort. This way, atleast recovery
> can be undertaken and the regions could be reassigned elsewhere. I also think
> that the master<->RS communication should get its own exclusive threadpool,
> but I'll wait until this issue has been sufficiently discussed before opening
> an issue ticket for that.
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