[Tutor] could someone please explain multiprocessing

[Alan Gauld]

On 05/07/2020 11:33, nathan tech wrote:

> import psutil
>   currently_running=[]
>   for process in running_processes:
>   if(process["name"]=="my_programs_launcher" or 
>      process["name"]=="my_programs_name"):
> 
>          running.append(process["id"])
>      if(len(running)==1):          # we are the only one! Launch the main program and job done.

I think you are doing more work than necessaary. You don;t need a list
of running instances since there is only  zero or one. - Its a boolean
condition. So just use the if test above.

>   else:
>    # we are already running. Open the shared file, append the arguments, 
> and then send a signal

Yep.

>    Main program:
>   # do all the things
>   # check to see if any signals have been received
>   if(signal_received):
>    # open the file and process it, deleting and or clearing the file 
> after so that it does not repeat itself. 

Yep. But... check out the signal module.
The actual code will be more event driven than the above.
You just set up the handler and the OS will work with the
Python virtual machine to call the handler when the signal
arrives.

>   if(file_last_modified(path)>last_time_this_program_accessed_it):
>     # process contents and update variables

Yep again.


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