CPU utilisation is confusing

[Bidgey225]

I have a question regarding the CPU utilisation of Python. When running a calculation, the CPU usage for Python sits at about 30%, which I initially thought would mean that only one of my four cores was being fully used. After checking task manager, it seems that all four cores are being used but each at about 30%

How can I enable Python to use all available resources?

(would post images with this but it's my first post and I'm not allowed :/ sorry)

[Ofnuts]

All four cores at 25% is the same than one single core at 100% (I assume the extra 5% is other activity on your machine). Unfortunately, due to the GIL you cannot efficiently use all four cores simultaneously with Python (or at least with CPython which is the usual implementation...). So you have to either find a non GIL-limited Python, or spread your work load across processes instead of threads, which isn't too hard to do with the multiprocessing module.

[Bidgey225]

Surely the fact that it is using four cores mean that it's a multithreaded workload, but it's not using these threads effectively and I was wondering if that can be improved at all. 
[Image: HTuxSUL.png]

[Image: OwjXMG3.png]

[nilamo]

...show some code?

[Bidgey225]

I'm new to this stuff so it's nothing too impressive

import random
import math
coprime = 0
cofactor = 0
sets = 0
while(sets<10000):
    random1 = random.randint(1, 1000)
    random2 = random.randint(1, 1000)
    i = 2
    while(True):
        if i==random1 or i==random2:
            coprime = coprime + 1
            break
        elif random1%i==0 and random2%i==0:
            cofactor = cofactor + 1
            i = i + 1
            sets = sets + 1

(it's still running btw, any help with improving efficiency would be greatly appreciated but I'm ok with leaving this to run)

[Ofnuts]

Surely the fact that it is using four cores mean that it's a multithreaded workload,

You are jumping to conclusions. It could be a single thread that ends up being dispatched about equally over the available cores. The CPU percentage is an average over a period (one second) which is somewhat bigger than a dispatcher time slice (tens of milliseconds).

[nilamo]

You have an infinite loop, though. If i is not equal to either random number, AND either of those numbers isn't divisible by i, your loop will never finish.
Which could explain why it's eating an entire core, without really doing anything.