[FIXED] difference between 'time python' and 'time python3'

Issue

what is the difference between using 'time python' and 'time python3' to check the execution time?

When I use time python test.py I get:

zsh: command not found: python
python test.py  0.00s user 0.00s system 56% cpu 0.003 total

whereas when I use time python3 test.py I get:

python3 test.py  0.05s user 0.01s system 90% cpu 0.064 total

Solution

The difference between time python and time python3 lies in the interpreter used to run your script. Here's a breakdown:

time python: Attempts to run the script using the default Python interpreter on your system.

This can be problematic because:

• Multiple Python versions might be installed: If both Python 2 and 3 are available, python might default to the older, slower Python 2, leading to inaccurate timing results.
• Default behavior can vary: Depending on your system configuration, the default interpreter might not be what you expect.

time python3: Explicitly specifies the Python 3 interpreter, ensuring your script runs with the desired version.

This guarantees:

• Accurate timing: You're measuring the performance of your script using the correct Python version.
• Improved performance: Python 3 offers significant performance improvements over Python 2, so you'll likely see faster execution times.

In your example, the difference in execution times observed with time python and time python3 likely reflects the use of two different Python versions. Python 2 being significantly slower explains the longer execution time with time python.

Therefore, for professional contexts and accurate timing, it's always recommended to use time python3 to explicitly specify the Python 3 interpreter and ensure consistent, representative results.

Answered By - Alex Pérez