Search⌘ K
AI Features
Home
Courses
Designing Elixir Systems with OTP

Starting Processes with Links

Explore how to start and link processes in Elixir using spawn_link and spawn_monitor. Understand the notification mechanisms between parent and child processes and how supervisors utilize these to handle failures effectively within OTP systems.

We'll cover the following...

Notifications

Supervisors are built on notification, an interesting primitive. Remember, when a process uses start_link/2 to create a child process, the Erlang BEAM will notify the parent process when the child process ends. This capability can work in a couple of ways.

spawn_link

First, using spawn_link causes all linked processes to end with the same error if any one of them ends. That may sound like a weird behavior to want, but if the top-level processes of our system end, we don’t want their child processes carrying on without them.

Here’s how spawn_link works. Let’s spawn a process that crashes, like this:

Executable

C++
spawn fn -> raise "boom" end

Output

iex(1)> spawn fn -> raise "boom" end
#PID<0.86.0>
iex(2)>
10:45:24.797 [error] Process #PID<0.86.0> raised
...