oslo.messaging/doc/source/reference/executors.rst

Executors

Executors control how a received message is scheduled for processing by a Server. This scheduling can be synchronous or asynchronous.

A synchronous executor will process the message on the Server's thread. This means the Server can process only one message at a time. Other incoming messages will not be processed until the current message is done processing. For example, in the case of an RPCServer only one method call will be invoked at a time. A synchronous executor guarantees that messages complete processing in the order that they are received.

An asynchronous executor will process received messages concurrently. The Server thread will not be blocked by message processing and can continue to service incoming messages. There are no ordering guarantees - message processing may complete in a different order than they were received. The executor may be configured to limit the maximum number of messages that are processed at once.

Available Executors

oslo.messaging.executors