What is the purpose of defining the user signal handler in src/tlapm.ml?

[ahelwer]

The file src/tlapm.ml has this code:

exception Stacktrace;;

let () =
  Sys.set_signal
    Sys.sigusr1
    (Sys.Signal_handle (fun _ -> raise Stacktrace));
  Tlapm_lib.init ();

So this registers a signal handler for the Sys.sigusr1 signal, which if received raises a Stacktrace exception. Sys.sigusr1 is a POSIX-standard signal ID reserved for custom user-defined signals. I can't find any other references to Sys.sigusr1 in the codebase, so this signal must originate outside of TLAPM - perhaps by running kill -s SIGUSR1 <tlapm PID> from the terminal while TLAPM is running.

The git blame command shows this was added by @johnyf back in 2021. @johnyf, do you remember why you added this? Is this some debug code which remains in the codebase?

[johnyf]

The change I made to those lines then was a formatting change. These lines were present from earlier in the file src/tlapm.ml.