Jobs and Message Queues
The business hosts process messages by means of jobs. A job is a CPU process that hosts the work done by a production. This terminology is intended to avoid confusion between CPU processes (jobs) and business processes (processes).
In general, a job is either running (processing a message) or it is not running. From a low-level, system viewpoint, a production consists almost entirely of jobs waiting to wake up to perform work.
A pool consists of one or more jobs. Each business host can have its own, private pool of allocated jobs — a pool with a specific size that cannot be exceeded.
When a business host receives a message, the business host assigns the work to a job from its pool. The job then performs the work. If no job is available, the business host waits for a job to become available. After the job completes the work, the job either returns to the pool or starts work on another message.
More formally, each message is assigned to a specific message queue, which handles messages in the order that it receives them. Each queue is associated with a single pool, and vice versa.
Unlike other types of business host, a business process can use a public pool (called the actor pool), which receives messages from a public queue (called the actor queue or Ens.ActorOpens in a new tab). The actor pool and actor queue are shared by all business processes that do not use private pools and queues.
For further information, see Pool Size and Actor Pool Size.
