Is Multithreading (in python) the same as calling the script multiple times?

Question

Let's assume we have some task, that could be divided into independent subtasks and we want to process these tasks in parallel on the same machine.

I read about multithreading and ran into this post, which describes GlobalInterpreterLocks. Since I do not understand fully how processes are handled under the hood, I got to ask:

Putting aside the gain of threading: Is Multithreading (in my case in python) effectively the same as calling a script multiple times?

I hope this question does not lead to far and its answer is understandable for someone whose knowledge about the things happening on the low levels of a computer are sparse. Thanks for any enlightening in this matter.

Answer 1

Is Multithreading (in my case in python) effectivle the same as calling a script multiple times?

In a word, no.

Due to the GIL, in Python it is far easier to achieve true parallelism by using multiple processes than it is by using multiple threads. Calling the script multiple times (presumably with different arguments) is an example of using multiple processes. The multiprocessing module is another way to achieve parallelism by using multiple processes. Both are likely to give better performance than using threads.

If I were you, I'd probably consider multiprocessing as the first choice for distributing work across cores.

Answer 2

It is not the same thing one is Multithreading while the other is opening separate process for one another:

here is a short explanation taken from here :

It is important to first define the differences between processes and threads. Threads are different than processes in that they share state, memory, and resources. This simple difference is both a strength and a weakness for threads. On one hand, threads are lightweight and easy to communicate with, but on the other hand, they bring up a whole host of problems including deadlocks, race conditions, and sheer complexity. Fortunately, due to both the GIL and the queuing module, threading in Python is much less complex to implement than in other languages.