Curator with Zookeeper Service Discovery connection forcibly closed

Question

I am trying out service discovery using Curator and Zookeeper.

The following is occurring when I try to register my service.

2014-09-23 16:36:09,755 [myid:] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxnFactory@197] - Accepted socket connection from /127.0.0.1:52026
2014-09-23 16:36:09,759 [myid:] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@868] - Client attempting to establish new session at /127.0.0.1:52026
2014-09-23 16:36:09,790 [myid:] - INFO  [SyncThread:0:ZooKeeperServer@617] - Established session 0x148a17bad590007 with negotiated timeout 40000 for client /127.0.0.1:52026
2014-09-23 16:36:11,735 [myid:] - WARN  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@362] - Exception causing close of session 0x148a17bad590007 due to java.io.IOException: An existing con
nection was forcibly closed by the remote host
2014-09-23 16:36:11,736 [myid:] - INFO  [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@1007] - Closed socket connection for client /127.0.0.1:52026 which had sessionid 0x148a17bad590007
2014-09-23 16:36:32,001 [myid:] - INFO  [SessionTracker:ZooKeeperServer@347] - Expiring session 0x148a17bad590006, timeout of 40000ms exceeded
2014-09-23 16:36:32,001 [myid:] - INFO  [ProcessThread(sid:0 cport:-1)::PrepRequestProcessor@494] - Processed session termination for sessionid: 0x148a17bad590006
2014-09-23 16:36:52,000 [myid:] - INFO  [SessionTracker:ZooKeeperServer@347] - Expiring session 0x148a17bad590007, timeout of 40000ms exceeded
2014-09-23 16:36:52,001 [myid:] - INFO  [ProcessThread(sid:0 cport:-1)::PrepRequestProcessor@494] - Processed session termination for sessionid: 0x148a17bad590007

The relevant code is as follows: (the getDiscovery method is the one which results in the above errors)

private ServiceDiscovery<InstanceDetails> getDiscovery() {
        return ServiceDiscoveryBuilder.builder(InstanceDetails.class)
            .basePath(Config.basePath)
            .client(curatorFramework)
            .serializer(jacksonInstanceSerializer)
            .build();
    }

I am using this in the following:

public void advertiseAvailability() {
    try {
        ServiceDiscovery<InstanceDetails> discovery = getDiscovery();
        discovery.start();
        discovery.registerService(getInstance()); // getInstance returns a ServiceInstance<InstanceDetails>
        discovery.close();
        System.out.println("Advertised");
    } catch (Exception e) {
        throw Throwables.propagate(e);
    }
}

Where the following is the configuration

public class Config{
    public static final String basePath = "/";
    public static final String serviceName = "myTestService1";
    public static final String address = "127.0.0.1";
    public static final int port = 2181;
}

the following is the initialisation of the required curatorFramework

    CuratorFramework curatorFramework;
    curatorFramework = CuratorFrameworkFactory.builder()
        .connectionTimeoutMs(1000)
        .retryPolicy(new RetryNTimes(10, 500))
        .connectString(Config.address+":"+Config.port)
        .build();
    curatorFramework.start();
    new EnsurePath(Config.basePath).ensure(curatorFramework.getZookeeperClient());

and the jacksonInstanceSerializer is as follows:

    this.jacksonInstanceSerializer = instanceSerializerFactory.getInstanceSerializer(
        new TypeReference<ServiceInstance<InstanceDetails>>() {}
    );

where instanceSerializerFactory is:

public class InstanceSerializerFactory {
    private final ObjectReader objectReader;
    private final ObjectWriter objectWriter;

    public InstanceSerializerFactory(ObjectReader objectReader, ObjectWriter objectWriter) {
        this.objectReader = objectReader;
        this.objectWriter = objectWriter;
    }

    public <T> InstanceSerializer<T> getInstanceSerializer(
            TypeReference<ServiceInstance<T>> typeReference) {
        return new JacksonInstanceSerializer<T>(objectReader, objectWriter, typeReference);
    }

}

final class JacksonInstanceSerializer<T> implements InstanceSerializer<T> {
    private final TypeReference<ServiceInstance<T>> typeRef;
    private final ObjectWriter objectWriter;
    private final ObjectReader objectReader;

    JacksonInstanceSerializer(ObjectReader objectReader, ObjectWriter objectWriter,
                              TypeReference<ServiceInstance<T>> typeRef) {
        this.objectReader = objectReader;
        this.objectWriter = objectWriter;
        this.typeRef = typeRef;
    }

Note: Instance Details it the contents I am trying to register (Name of service and address etc)

Answer 1

The connection seems to be closing down from the client side. Zookeeper sessions are bound to the connection between the zookeeper server and the client (using curator in your case). Most probably, the client is closing down and thus the server is identifying this scenario and closing off your session.