The OddJob.Async.Proxy links the job caller to the worker as the job is being performed.

The process that calls async_perform/2 or async_perform_many/3 must link and monitor the worker performing the job so it can receive the results and be notified of failure by exiting or receiving an :EXIT message if the process is trapping exits. However, at the time the function is called it is unknown which worker will receive the job and when. The proxy is a process that is created to provide a link between the caller and the worker.

When an async funcion is called, the caller links and monitors the proxy, and the proxy pid and monitor reference are stored in the OddJob.Job struct. When the worker receives the job it calls the proxy to be linked and monitored. Job results as well as :EXIT and :DOWN messages are passed from the worker to the caller via the proxy.