Like fidotron said, a process's internal state is lost if it crashes (or exits).
If you want that state to be durable, you need to store it durably. Mnesia provides (optional) distributed transactions which may be appropriate for durability needs (lots of details). Or you could externalize durability to other systems.
Erlang is wonderful, but it's not magic. It won't prevent hardware failures, so if an Erlang process fetches something from a queue and the cpu stops for whatever reason, you've got a tricky situation. Erlang does offer a way for a process to monitor other processes, including processes on remote nodes, so your process will be notified if the other process crashes or if the other node is disconnected; but if the other node is disconnected, you don't know what happened to the other process --- maybe it's still running and there's a connectivity issue, maybe the whole host OS crashed. You could perhaps set bidirectional monitors, and then know that the remote process would be notified of the disconnection as well, if it still was running... but you wouldn't know if the process finished (sucessfully or not) after the connectivity failed but before the failure was detected and processed.
If you want that state to be durable, you need to store it durably. Mnesia provides (optional) distributed transactions which may be appropriate for durability needs (lots of details). Or you could externalize durability to other systems.
Erlang is wonderful, but it's not magic. It won't prevent hardware failures, so if an Erlang process fetches something from a queue and the cpu stops for whatever reason, you've got a tricky situation. Erlang does offer a way for a process to monitor other processes, including processes on remote nodes, so your process will be notified if the other process crashes or if the other node is disconnected; but if the other node is disconnected, you don't know what happened to the other process --- maybe it's still running and there's a connectivity issue, maybe the whole host OS crashed. You could perhaps set bidirectional monitors, and then know that the remote process would be notified of the disconnection as well, if it still was running... but you wouldn't know if the process finished (sucessfully or not) after the connectivity failed but before the failure was detected and processed.