[erlang-questions] Can not kill the registered process

Rick Pettit <>
Wed Jan 14 00:25:34 CET 2015


Doh!

I didn’t realize I had my wifi disabled when I replied to your original email (and so didn’t see the replies others had already sent you indicating the problem was your calling of exit/1 vs. exit/2).

Sorry for the redundant reply.

-Rick

On Jan 13, 2015, at 5:17 PM, Rick Pettit <> wrote:

> I think you want to replace your call to exit/1 with an appropriate call to exit/2.
> 
> The way you have it written your shell is committing suicide (as opposed to murder :-)
> 
> -Rick
> 
> On Jan 13, 2015, at 4:23 PM, Harit Himanshu <> wrote:
> 
>> The problem I am trying while learning from exercises from Joe's book is 
>> 
>> Write a function that creates a registered process that writes out "I’m still running" every five seconds. Write a function that monitors this process and restarts it if it dies. Start the global process and the monitor process. Kill the global process and check that it has been restarted by the monitor process.
>> 
>> So I created the runner and monitor_runner as  
>> 
>> runner() ->
>>  receive
>>  after 5 * 1000 ->
>>    io:format("I am running.~n"),
>>    runner()
>>  end.
>> 
>> monitor_runner() ->
>>  spawn(fun() ->
>>    {Pid, Ref} = spawn_monitor(error_handling, runner, []),
>>    io:format("started new process ~p and reference ~p.~n", [Pid, Ref]),
>>    register(runner, Pid),
>>    receive
>>      {'DOWN', Ref, process, Pid, _Why} ->
>>        io:format("runner got killed, restarting"),
>>        monitor_runner();
>>      X -> X
>>    end
>>  end).
>> 
>> 
>> When I run this, I get  
>> 1> c(error_handling).
>> {ok,error_handling}
>> 2> Pid = error_handling:monitor_runner().
>> started new process <0.40.0> and reference #Ref<0.0.0.77>.
>> <0.39.0>
>> I am running.
>> 3> 
>> 3> 
>> I am running.
>> 3> Pid.
>> <0.39.0>
>> I am running.
>> I am running.
>> I am running.
>> I am running.
>> I am running.
>> 4> whereis(runner).
>> <0.40.0>
>> I am running.
>> 6> exit(whereis(runner)).
>> ** exception exit: <0.40.0>
>> I am running.
>> I am running.
>> I am running.
>> I am running.
>> I am running.
>> I am running.
>> I am running.
>> 7> 
>> 
>> Problem?
>> The runner is still running.
>> 1.) Why is the process not getting killed?
>> 2.) Why is it not caught by {'DOWN'....}
>> 
>> What am I missing here?
>> 
>> Thanks
>> + Harit
>> _______________________________________________
>> erlang-questions mailing list
>> 
>> http://erlang.org/mailman/listinfo/erlang-questions
> 



More information about the erlang-questions mailing list