运行多个python脚本和多处理之间有什么区别

Question

I was thinking about adding multiprocessing to one of my scripts to increase performance.

It's nothing fancy, there are 1-2 parameters to the main method.

Is there anything wrong with just running four of the same scripts cloned on the terminal versus actually adding multiprocessing into the python code?

ex for four cores:

~$ script.py & 
   script.py &
   script.py &
   script.py;

I've read that linux/unix os's automatically divide the programs amongst the available cores.

Sorry if ^ stuff i've mentioned above is totally wrong. Nothing above was formally learned, it was just all online stuff.

Answer 1

Martijn Pieters' comment hits the nail on the head, I think. If each of your processes only consumes a small amount of memory (so that you can easily have all four running in parallel without running out of RAM) and if your processes do not need to communicate with each other, it is easiest to start all four processes independently, from the shell, as you suggested.

The python multiprocessing module is very useful if you have slightly more complex requirements. You might, for instance, have a program that needs to run in serial at startup, then spawn several copies for the more computationally intensive section, and finally do some post-processing in serial. multiprocessing would be invaluable for this sort of synchronization.

Alternatively, your program might require a large amount of memory (maybe to store a large matrix in scientific computing, or a large database in web programming). multiprocessing lets you share that object among the different processes so that you don't have n copies of the data in memory (using multiprocessing.Value and multiprocessing.Array objects).

Answer 2

Using multiprocessing might also become the better solution if you'd want to run your script, say, 100 times on only 4 cores. Then your terminal-based approach would become pretty nasty.

In this case you might want to use a Pool from the multiprocessing module.