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From "Fangmin Lv (JIRA)" <j...@apache.org>
Subject [jira] [Created] (ZOOKEEPER-3296) Cannot join quorum due to Quorum SSLSocket connection not closed explicitly when there is handshake issue
Date Thu, 07 Mar 2019 18:08:00 GMT
Fangmin Lv created ZOOKEEPER-3296:
-------------------------------------

             Summary: Cannot join quorum due to Quorum SSLSocket connection not closed explicitly
when there is handshake issue
                 Key: ZOOKEEPER-3296
                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3296
             Project: ZooKeeper
          Issue Type: Bug
          Components: server
    Affects Versions: 3.5.4, 3.6.0
            Reporter: Fangmin Lv
            Assignee: Fangmin Lv
             Fix For: 3.6.0, 3.5.4


Recently, on prod ensembles, we saw some peers failed to connect to others due to timed out
when connecting to the other's leader election port. This was triggered by a network incident
with lots of packet loss.

After investigation, we found it's because we doesn't close the socket explicitly when it
timed out during ssl handshake in QuorumCnxManager.connectOne.

The quorum connection manager is handling connections sequentially with a default listen backlog
queue size 50, during the network loss, there are socket read timed out, which is syncLimit
* tickTime, and almost all the following connect requests in the backlog queue will timed
out from the other side before it's being processed. Those timed out learners will try to
connect to a different server, and leaves the connect requests on server side without sending
the close_notify packet. The server is slowly consuming from these queue with syncLimit *
tickTime timeout for each of those requests which haven't sent notify_close packet. Any new
connect requests will be queued up again when there is spot in the listen backlog queue, but
timed out before the server handles it, and it can never successfully finish any new connection,
so it failed to join the quorum. And the peers are leaking FD because all those connections
are in CLOSE-WAIT state.
 
Restarting the servers to drain the listen backlog queue mitigated the issue.



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