Oban: error handling and job retry

[sorentwo]

@marcin

I created an Oban worker that start_links to the GenServer Foo and waits using receive for a message from Foo, that it has completed its job.

Is this the only place you’re using the Foo gen server? If so, perhaps you don’t need to use a separate GenServer or process at all. Each job in Oban runs as an isolated process already.

@marcin

I created an Oban worker that start_links to the GenServer Foo and waits using receive for a message from Foo, that it has completed its job.

I thought that if Foo dies, the worker will die as well and Oban will restart it. Wrong: Oban worker will only be restarted if it raises and error, not if it gets killed.

This can work, you’d just need to call Process.flag(:trap_exit, true) within the Oban job to ensure that it receives an :EXIT, pid, reason message rather than crashing the process. By default Oban jobs do not trap exits.

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Sending messages between processes will always add a little bit of complexity: passing pids, sending messages and monitoring are par for the course. If possible, I’d first try to put all of this within a single process. Failing that, I would try to use a Task rather than a GenServer and simplify the message passing.