Because the Elixir documentation (as well as the Erlang documentation of :erlang.exit/2, which this function delegates to) only mention “sends an exit signal”, I am fairly certain that the function is asynchronous.

The approach mentioned by @lud works. However, this will not (always) prevent other code from running on pid before it exits. It will only prevent code running on the process calling Process.exit to wait with continuing before pid has exited.

However, another question would be: what are you trying to do? It seems like a rather odd request. Maybe your actual problem can be resolved in a wholly different manner.

From the documentation of Process.monitor/1:

If the process is already dead when calling Process.monitor/1 , a :DOWN message is delivered immediately.

So you will receive the :DOWN message in that case as well.

Also if you call Process.monitor on a pid that is not alive, the down message will contain :noproc as the reason, so you will know your process was not alive.

if you use spawn_monitor/3 you will remove the race condition on starting the process