If your application creates a large number of asynchronous operations, you may also encounter timeouts immediately in response to the requests. When you perform an asynchronous operation, Couchbase Java SDK creates an object and puts the object into a request queue. The object and the request are stored in Java runtime memory, in other words, they are stored in local to your Java application runtime memory and require some amount of Java Virtual Machine IO to be serviced.

Rather than write so many asynchronous operations that can overwhelm a JVM and generate out of memory errors for the JVM, you can rely on SDK-level timeouts. The default behavior of the Java SDK is to start to immediately timeout asynchronous operations if the queue of operations to be sent to the server is overwhelmed.

You can also choose to control the volume of asynchronous requests that are issued by your application by setting a timeout for blocking. You might want to do this for a bulk load of data so that you do not overwhelm your JVM. The following is an example:

List<URI> baselist = new ArrayList<URI>();
        baselist.add(new URI("http://localhost:8091/pools"));

        CouchbaseConnectionFactoryBuilder cfb = new CouchbaseConnectionFactoryBuilder();
        cfb.setOpQueueMaxBlockTime(5000); // wait up to 5 seconds when trying to enqueue an operation

        CouchbaseClient myclient = new CouchbaseClient(cfb.buildCouchbaseConnection(baselist, "default", "default", ""));