I'm seeing an occasional AcidicJob::ArgumentMismatchError:

existing execution's arguments do not match (AcidicJob::ArgumentMismatchError)
existing: [{"_aj_globalid" => "gid://tour-brain/NewCommentNotifier/1049"}]
expected: [{"_aj_globalid" => "gid://tour-brain/NewCommentNotifier/1052"}]

Which really throws me for a loop.

I figured it must be because it's somehow finding the execution from a different job, and those are identified by a unique idempotency_key. If I retry the job, the error goes away and the job is executed just fine.

That pointed me in a direction though!

Let's take a step back from my error and use the example from the README.

In the RideCreateJob example a User object is passed as one of the arguments to unique_by (I also pass an object in my code).

The code that generates the idempotency key is as following:

The part that dumps the JSON would translate to something similar to:

JSON.dump(["RideCreateJob", [User.first, { some_param: 123 }]])
# => "[\"RideCreateJob\",[\"#<User:0x0000000158e7d5c0>\",{\"some_param\":123}]]"
#                           ^^^^^^^^^^^ 😱 ^^^^^^^^^^^

As you can see, the User object is inserted as it's string representation (to_s) with the object id of that instance. This is not idempotent at all and generates a new key every time. I'm guessing the ids are sequenced similarly between my puma threads/workers and that's what causing my errors, but I don't know enough of Ruby's internals to be sure.

I'm not even sure if the whole thing works as it's supposed to with this, I can't fully wrap my head around it 😅 but I guess it won't retry properly because it will instantiate a new Execution every time? At least I think right now you shouldn't pass Ruby class instances as the value for unique_by.

My own solution for now, is to pass objects to unique_by by their to_global_id value.

execute_workflow(unique_by: @event.to_global_id) do |w|
  # ...
end

But I feel that ideally this should be solved in acidic job itself.

I'm not sure what a proper solution would look like, though. Maybe there's something in how Active Job serializes it's arguments that can be used?