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From "cheng ren (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-11038) Is node being restarted treated as node joining?
Date Wed, 20 Jan 2016 01:06:39 GMT
cheng ren created CASSANDRA-11038:
-------------------------------------

             Summary: Is node being restarted treated as node joining?
                 Key: CASSANDRA-11038
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11038
             Project: Cassandra
          Issue Type: Bug
            Reporter: cheng ren


Hi, 
What we found recently is that every time we restart a node, all other nodes in the cluster
treat the restarted node as a new node joining and issue node joining notification to clients.
We have traced the code path being hit when a peer node detected a restarted node:

src/java/org/apache/cassandra/gms/Gossiper.java
{code}
    private void handleMajorStateChange(InetAddress ep, EndpointState epState)
    {
        if (!isDeadState(epState))
        {
            if (endpointStateMap.get(ep) != null)
                logger.info("Node {} has restarted, now UP", ep);
            else
                logger.info("Node {} is now part of the cluster", ep);
        }
        if (logger.isTraceEnabled())
            logger.trace("Adding endpoint state for " + ep);
        endpointStateMap.put(ep, epState);

        // the node restarted: it is up to the subscriber to take whatever action is necessary
        for (IEndpointStateChangeSubscriber subscriber : subscribers)
            subscriber.onRestart(ep, epState);

        if (!isDeadState(epState))
            markAlive(ep, epState);
        else
        {
            logger.debug("Not marking " + ep + " alive due to dead state");
            markDead(ep, epState);
        }
        for (IEndpointStateChangeSubscriber subscriber : subscribers)
            subscriber.onJoin(ep, epState);
    }

{code}

subscriber.onJoin(ep, epState) ends up with calling onJoinCluster in Server.java

{code}
src/java/org/apache/cassandra/transport/Server.java
        public void onJoinCluster(InetAddress endpoint)
        {
server.connectionTracker.send(Event.TopologyChange.newNode(getRpcAddress(endpoint), server.socket.getPort()));
        }
{code}

We have a full trace of code path and skip some intermedia function calls here for being brief.


Upon receiving the node joining notification, clients would go and scan system peer table
to fetch the latest topology information. Since we have tens of thousands of client connections,
scans from all of them put an enormous load to our cluster. 

Although in the newer version of driver, client skips fetching peer table if the new node
has already existed in local metadata, we are still curious why node being restarted is handled
as node joining on server side? Did we hit a bug or this is the way supposed to be? Our old
java driver version is 1.0.4 and cassandra version is 2.0.12.

Thanks!




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