Supervisor shutdown

[Raimo Niskanen]

The idea of tossing around a State variable in the gen_server is to 
store such things as a pid() for a reply. State is commonly a record, so 
just add a field. Using the process dictionary is more "ugly", since it 
is used by e.g the gen_server code itself.

If your worker processes have such an intircate protocol with the 
gen_server you might think about if they should form a supervision tree 
of their own, and your current gen_server should be a supervisor. It is 
a common tactic to not let the worker processes trap exit, and just get 
instantly killed when the gen_server exits, provided you can make them 
stupid enough. Making a new supervision tree is probably too heavy, though.

-- 
/ Raimo Niskanen, Erlang/OTP, Ericsson AB




HEINRICH VENTER wrote:
>>    -the gen_server has been set to trap exit signals, and
> 
> I seem to have missed this bit.  Now that it traps the exit signals with 
> 
> process_flag(trap_exit, true)
> 
> Everything works out smoothely, or rather more smoothely.
> 
> I have a spanner to throw in the works now however :)
> 
> The gen_sever spawns some worker processes that need to be termianted.  These processes might not terminate immediately when the stop message is sent to them. (I have discovered a falw in the curent design but will post to a separate thread about this)  The gen_server can not terminate before all its workers have terminated in an orderly fasion, BUT since the stop function executes in a handle_call and the workers notify the gen_server of their termination through a different handle_call.
> This brings me to the {noreply, State} mentioned in another thread.
> How do I know the PID where to send the response at the later time when I am ready to quit?  The process dictionary perhaps? Then use the function that notifies the gen_server of the process termination to check if all the processes are down and then reply with the {stop, normal, ok, State} message instead of {reply, State}
> Does this make sense?
> 
> -]-[einrich
> 
> #####################################################################################
> The information contained in this message and or attachments is intended
> only for the person or entity to which it is addressed and may contain
> confidential and/or privileged material.  Any review, retransmission,
> dissemination or other use of, or taking of any action in reliance upon,
> this information by persons or entities other than the intended recipient
> is prohibited. If you received this in error, please contact the sender and
> delete the material from any system and destroy all copies.
> #####################################################################################