Sudarshan Kadambi created HBASE-12028:
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Summary: 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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