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https://issues.apache.org/jira/browse/HBASE-12028?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14140931#comment-14140931
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stack commented on HBASE-12028:
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bq. I'm still unclear about the root cause for HBASE-11813
A query that returned thousands of empty results turned what was thought an
harmless recursion (triggered by empty result) pathological... it recursed so
much it overflowed the allocated stack.
You have a couple of points both that we are mortally wounded if we lose a
handler and that killing the RS could end up taking down the whole cluster.
> 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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