# How do I profile a Python script?

By default, Python contains a profiler called `cProfile`. It not only gives the total running time, but also times each function separately, and tells you how many times each function was called, making it easy to determine where you should make optimizations.

You can call it from within your code:

```python
import cProfile

cProfile.run('foo()')
```

Even more usefully, you can invoke the `cProfile` when running a script:

```bash
python -m cProfile myscript.py
```

With the output similar to this:

```
1007 function calls in 0.061 CPU seconds

Ordered by: standard name
ncalls  tottime  percall  cumtime  percall filename:lineno(function)
    1    0.000    0.000    0.061    0.061 <string>:1(<module>)
 1000    0.051    0.000    0.051    0.000 euler048.py:2(<lambda>)
    1    0.005    0.005    0.061    0.061 euler048.py:2(<module>)
    1    0.000    0.000    0.061    0.061 {execfile}
    1    0.002    0.002    0.053    0.053 {map}
    1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler objects}
    1    0.000    0.000    0.000    0.000 {range}
    1    0.003    0.003    0.003    0.003 {sum}
```

To learn more about `cProfile`, you can visit the [official documentation](https://docs.python.org/3/library/profile.html#module-cProfile).