Programmer Musings

Worker thread patterns

Any system that uses the worker pattern may also want a dispatcher thread that wakes up workers and sends them on their way. In this approach, the dispatcher thread handles setting up the data needed to finish the task. The dispatcher may either choose a worker from a pool of suspended threads or create a new thread to perform the work. Many server programs use a similar approach. In that case, the dispatcher thread may be waiting on a socket and passes the request to a worker when the request is received.

Another approach would be to make all of the threads identical (no dispatcher thread). The worker threads could wait on a synchronized work queue object or socket. As each request is received, a thread is awakened by the OS and given control of the request. Although it sounds a little strange not to have control over which thread does what work, this can actually be a very efficient way to work.

This latter approach is called the team model in Tanenbaum's Modern Operating Systems.