[jira] [Created] (KAFKA-12971) Kakfa 1.1.x clients cache broker hostnames, client stuck when host is swapped for the same broker.id

["GEORGE LI (Jira)" <ji...@apache.org>]

GEORGE LI created KAFKA-12971:
---------------------------------

             Summary: Kakfa 1.1.x clients cache broker hostnames,  client stuck when host is swapped for the same broker.id
                 Key: KAFKA-12971
                 URL: https://issues.apache.org/jira/browse/KAFKA-12971
             Project: Kafka
          Issue Type: Bug
          Components: clients
    Affects Versions: 1.1.1, 1.1.0, 1.1.2
            Reporter: GEORGE LI
             Fix For: 2.1.2


There was an upgrade of kafka-client version from 0.11 to 1.1.x to fix a bug in 0.11 with too frequent consumer offset commits.  Due to the Flink version, it can be directly using latest 2.x kafka-client version. 

{code}
Error sending fetch request (sessionId=178328175, epoch=INITIAL) to node 425: org.apache.kafka.common.errors.DisconnectException.
{code}

some consumers were stuck with above messages with broker.id 425 had hardware failures and got swapped with a different hostname. 

Comparing the {{ClusterConnectionStates.connecting()}} of the 3 versions: 

0.11.0.3: 

{code}
    public void connecting(String id, long now, String host, ClientDnsLookup clientDnsLookup) {
        nodeState.put(id, new NodeConnectionState(ConnectionState.CONNECTING, now, this.reconnectBackoffInitMs, host, clientDnsLookup));
    }
{code}


1.1.x: 

{code}
     public void connecting(String id, long now, String host, ClientDnsLookup clientDnsLookup) {
        if (nodeState.containsKey(id)) {
            NodeConnectionState connectionState = nodeState.get(id);
            connectionState.lastConnectAttemptMs = now;
            connectionState.state = ConnectionState.CONNECTING;
            // Move to next resolved address, or if addresses are exhausted, mark node to be re-resolved
            connectionState.moveToNextAddress();
        } else {
            nodeState.put(id, new NodeConnectionState(ConnectionState.CONNECTING, now,
                this.reconnectBackoffInitMs, host, clientDnsLookup));
        }
    }
{code}


2.2.x: 

{code}
    public void connecting(String id, long now, String host, ClientDnsLookup clientDnsLookup) {
        NodeConnectionState connectionState = nodeState.get(id);
        if (connectionState != null && connectionState.host().equals(host)) {
            connectionState.lastConnectAttemptMs = now;
            connectionState.state = ConnectionState.CONNECTING;
            // Move to next resolved address, or if addresses are exhausted, mark node to be re-resolved
            connectionState.moveToNextAddress();
            return;
        } else if (connectionState != null) {
            log.info("Hostname for node {} changed from {} to {}.", id, connectionState.host(), host);
        }

        // Create a new NodeConnectionState if nodeState does not already contain one
        // for the specified id or if the hostname associated with the node id changed.
        nodeState.put(id, new NodeConnectionState(ConnectionState.CONNECTING, now,
            this.reconnectBackoffInitMs, host, clientDnsLookup));
    }
{code}


From above, the {{0.11.0.3}} is just putting the node to the NodeState HashMap to retry with update host.

In {{1.1.x}}, it adds a logic of "caching". {{if (nodeState.containsKey(id))}}, However, if the HOSTNAME of the broker.id is swapped/changed, it never gets to the else block to update the NodeState with the new hostname.

In {{2.2.x}}, it adds an additional check {{if (connectionState != null && connectionState.host().equals(host))}}, if the Hostname changed, then called {{nodeState.put()}} to update the host.

So from above, it looks like the 1.1.x caching logic introduced a bug of not updating the nodeState()'s host when that is changed (e..g host failure, swap with a different hostname, but use the same broker.id).





--
This message was sent by Atlassian Jira
(v8.3.4#803005)