# Python Profiling (cProfile)

`cProfile` is a built-in Python module for profiling the performance of your Python programs. It provides deterministic profiling of Python programs, meaning it measures the time spent in each function.

## Basic Usage

### Command Line

You can run `cProfile` directly from the command line to profile a script.

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

To sort the output by cumulative time (time spent in the function and all sub-functions), use the `-s` option:

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

### Inside Python Code

You can also use `cProfile` within your Python code.

```python
import cProfile

def my_function():
    total = 0
    for i in range(10000):
        total += i
    return total

cProfile.run('my_function()')
```

## Analyzing Output with `pstats`

For more complex analysis, you can save the profile data to a file and analyze it using the `pstats` module.

```python
import cProfile
import pstats

def my_function():
    # ... some code ...
    pass

# Profile and save to file
cProfile.run('my_function()', 'output.prof')

# Analyze the saved data
p = pstats.Stats('output.prof')
p.sort_stats('cumulative').print_stats(10) # Print top 10 functions by cumulative time
```

## Common Sort Keys

*   `'calls'`: Call count
*   `'cumulative'`: Cumulative time
*   `'file'`: File name
*   `'line'`: Line number
*   `'module'`: Module name
*   `'name'`: Function name
*   `'nfl'`: Name/file/line
*   `'pcalls'`: Primitive call count
*   `'stdname'`: Standard name
*   `'time'`: Internal time (time spent in the function itself, excluding sub-functions)

[[programming/python/python]]