Github user nicom commented on the pull request:
https://github.com/apache/storm/pull/639#issuecomment-203982738
@caofangkun
Sorry for commenting on such an old pull request, but we recently also
encountered the problem this patch is trying to address.
> Does have any situation will call (.close socket) but not removed from
cached-node+port->socket ?
Indeed there is one other situation where the close() method is called:
https://github.com/apache/storm/blob/v0.9.6/storm-core/src/jvm/backtype/storm/messaging/netty/Client.java#L505
This only happens if the number of reconnects reaches the number set in the
'storm.messaging.netty.max_retries' config setting (I believe the default is
300). But the problem is aggravated by the fact, that the `connectionAttempts`
counter is never reset. So if a topology runs for a long enough time this might
become a problem.
Actually this issue has been fixed in 0.10.0
There is another more serious issue that lead to huge problem in one of out
topologies whenever a worker crashed due to some exception.
If worker A sucessfully connects to worker B for the first time during
startup but worker B closes the connection for some reason before the
`:worker-active-flag` is set to true (here
https://github.com/apache/storm/blob/v0.9.6/storm-core/src/clj/backtype/storm/daemon/worker.clj#L356),
there will be no further reconnect attempts, since no messages will be
processed and neither `send()` nor `flushMessages()` will ever be called.
In our case this frequenty happened because nimbus often rescheduled the
whole toplogy right around the same time when the supervisor restarted the
failed worker, leading to a race condition. This might have to do with the fact
that `nimbus.task.timeout.secs` and `supervisor.worker.timeout.secs` have the
same value by default.
Tedxia's patch won't fix this problem I belive, since the status returned
by `status()` will be `ConnectionWithStatus$Status/Connecting` in this
situation.
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