Question

I’m using the Mongo Java driver (2.8.0) to connect to a Mongo instance.

I noticed that if I restart mongod, then the first operation after the restart (even a simple count()) always fails with EOFException or a Broken pipe.

I’m using the following Mongo options:

opts.autoConnectRetry = true;
opts.maxAutoConnectRetryTime = 2000L;
opts.connectTimeout = 30000;
opts.socketTimeout = 60000;

Is there a way to tell the driver to try to re-establish the connections? I thought that “autoReconnectRetry” will do that, but that only works after the connection is “discovered” (through a single failed operation) to be broken.

Answer 1

The AutoConnectRetry option will retry when opening a connection to the server, but doesn’t guarantee you won’t get a read exception. You still need to handle exceptions in your application and retry if appropriate.

Blurb from the docs:

If true, the driver will keep trying to connect to the same server in case that the socket cannot be established. There is maximum amount of time to keep retrying, which is 15s by default. This can be useful to avoid some exceptions being thrown when a server is down temporarily by blocking the operations. It also can be useful to smooth the transition to a new master (so that a new master is elected within the retry time). Note that when using this flag: – for a replica set, the driver will trying to connect to the old master for that time, instead of failing over to the new one right away – this does not prevent exception from being thrown in read/write operations on the socket, which must be handled by the application. Even if this flag is false, the driver already has mechanisms to automatically recreate broken connections and retry the read operations. Default is false.