By default, the outbound document store (client side queue) can contain a maximum of 500,000 documents. After the outbound document store reaches capacity, the server "blocks" or "pauses" any threads that are executing services that publish documents. The threads remain blocked until the server begins draining the outbound document store.

The watt.server.control.maxPersist server parameter determines the capacity of the outbound document store. If you plan to bring the Broker down for an extended time period, consider editing this parameter to lower the capacity of the outbound document store. If you keep the outbound document store at the default capacity, and the Broker becomes unavailable, it is possible that storing outbound documents could exhaust memory and cause Integration Server to fail. If the outbound document store has a lower capacity, Integration Server will block threads instead of continuing to use memory by storing documents.