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Posted to dev@zookeeper.apache.org by "Raul Gutierrez Segales (JIRA)" <ji...@apache.org> on 2015/06/02 23:44:50 UTC

[jira] [Created] (ZOOKEEPER-2202) Cluster crashes when reconfig adds an unreaachable observer

Raul Gutierrez Segales created ZOOKEEPER-2202:
-------------------------------------------------

             Summary: Cluster crashes when reconfig adds an unreaachable observer
                 Key: ZOOKEEPER-2202
                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2202
             Project: ZooKeeper
          Issue Type: Bug
            Reporter: Raul Gutierrez Segales


While adding support for reconfig() in Kazoo (https://github.com/python-zk/kazoo/pull/333) I found that the cluster can be crashed if you add an observer whose election port isn't reachable (i.e.: packets for that destination are dropped, not rejected). This will raise a SocketTimeoutException which will bring down the PrepRequestProcessor:

{code}
2015-06-02 14:37:16,473 [myid:3] - WARN  [ProcessThread(sid:3 cport:-1)::QuorumCnxManager@384] - Cannot open channel to 100 at election address /8.8.8.8:38703
java.net.SocketTimeoutException: connect timed out
        at java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
        at java.net.Socket.connect(Socket.java:589)
        at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:369)
        at org.apache.zookeeper.server.quorum.QuorumPeer.connectNewPeers(QuorumPeer.java:1288)
        at org.apache.zookeeper.server.quorum.QuorumPeer.setLastSeenQuorumVerifier(QuorumPeer.java:1315)
        at org.apache.zookeeper.server.quorum.Leader.propose(Leader.java:1056)
        at org.apache.zookeeper.server.quorum.ProposalRequestProcessor.processRequest(ProposalRequestProcessor.java:78)
        at org.apache.zookeeper.server.PrepRequestProcessor.pRequest(PrepRequestProcessor.java:877)
        at org.apache.zookeeper.server.PrepRequestProcessor.run(PrepRequestProcessor.java:143)
{code}

A simple repro can be obtained by using the code in the referenced pull request above and using 8.8.8.8:3888 (for example) instead of a free (but closed) port in the loopback. 

I think that adding an Observer (or a Participant) that isn't currently reachable is a valid use case (i.e.: you are provisioning the machine and it's not currently needed) so I think we could handle this with lower connect timeouts, not sure. 




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