Python 3.11 dis tests

30 Jul 2023

I recently found out about dis module in Python. I wrote two simple functions.

def function_1(x, y):
  x + y


def function_2(x, y);
  return x + y

I used dis module to find out about the bytecode operations for each function.

from dis import dis

print("="*60)
dis(function_1)
print("="*60)
dis(function_2)
print("="*60)

I thought the first function would have fewer bytecode operations. But this is the output I got from the dis module.

============================================================
  5           0 RESUME                   0

  6           2 LOAD_FAST                0 (y)
              4 LOAD_FAST                1 (z)
              6 BINARY_OP                0 (+)
             10 POP_TOP
             12 LOAD_CONST               0 (None)
             14 RETURN_VALUE
============================================================
  9           0 RESUME                   0

 10           2 LOAD_FAST                0 (y)
              4 LOAD_FAST                1 (z)
              6 BINARY_OP                0 (+)
             10 RETURN_VALUE
============================================================

Turns out the first function has more bytecode operations. It loads the None value and return it. I wanted to run some tests around the running time. I ran the function for thousands of times and recorded the running time.

Above two figures shows the difference between function_1 and function_2 execution time on an AMD Dual core processors. I was hoping to see more clear evidence, I thought function_2 would be slightly faster. X axis shows number of times I ran the functions in a loop. Y axis shows the difference in time (function_1 time - function_2 time).

Above two charts shows the same test on an Intel chip. I don’t see any clear evidence.

I ran the same number of functions calls for 250 times and got this variation in differences. I am still not sure about the results. I will investigate this further.

Python 3.11 dis tests

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