Raul Gutierrez Segales created ZOOKEEPER-2202:
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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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