Protect to avoid process crash in rush

[icebob]

If you start a loadtest and don't wait for responses, the producer creates Promises & collect them while the responses receive. If they don't receive quickly, the producer node starts eating the memory, while reaches the myth 1.4GB RAM and the process crashes.

We need a limit (e.g 50k) in the queue. If the requests reach this limit, throw a QueueIsFullError (retryable) error instead.

Proposal

const broker = new ServiceBroker({
    ...
    transit: {
          maxQueueSize: 50 * 1000, // default value
    }
    ...
});

50k ~ 400MB RAM

[icebob]

Implemented. Released in v0.11.2