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Erlang / Erlang Basics Interview questions

What is the difference between spawn and spawn_link?

Both start a new process and return its PID, but they differ in what happens when that new process terminates abnormally.

spawnspawn_link
Caller and new process are independent; if the child crashes, the caller is unaffected. Caller and new process are linked; if either crashes, the other receives an exit signal too.
You must set up monitoring manually to be notified of a crash. By default, an abnormal exit propagates and kills the linked process unless it's trapping exits.

Because a crash silently propagating can be exactly what you want (fail the whole group together) or exactly what you don't (an isolated worker), OTP supervisors use spawn_link internally combined with process_flag(trap_exit, true), so the supervisor is notified of the crash instead of being killed by it.

By default, what happens to the caller if a process started with spawn_link crashes?
How do supervisors typically avoid being killed by a linked child's crash?

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