1. A system to execute within a host organization, wherein the system comprises: a processor and a memory; wherein the system executes instructions via the processor and memory which cause the system to perform the following operations: receiving messages at a message broker; enqueuing the received messages within a message queue of the message broker; establishing a push connection from the broker to a thread and pushing an initial message from the message queue to the thread and processing the initial message via the thread; establishing a pull connection from the thread to the broker and requesting one or more additional messages from the message queue, and bulk processing the one or more additional messages with the initial message from the broker; issuing a database query via a query interface by issuing the database query from the thread to a data store, wherein the database query specifies the initial message and the one or more additional messages as a set of messages and obtaining a lock for the set of messages; and handling, via a message processing engine, by processing the set of messages in bulk when the lock for the set of messages is obtained and re-enqueuing any of the set of messages for which the lock is not obtained.