As the name suggests this is the exception which occurs when producer systems sending more messages above and beyond the capacity of the broker system then brokers would not be able to handle the same. The queue gets full at broker end so no incoming request can be handled any more. As producer systems do not have any information on the capacity of the broker system results in such exceptions. The messages get overflowed at broker end. To avoid such a scenario we should have multiple systems working as a broker system so messages can be evenly distributed across multiple systems. The clusters environment where we have multiple nodes servicing the message processing avoid such exceptions to occur. The clustering, partitioning helps in avoiding any such exceptions.