pyftrace is a lightweight Python function tracing tool designed to monitor and report on function calls within Python scripts. It leverages Python 3.12's sys.monitoring to monitor Python events and trace functions based on the results. With pyftrace, you can trace function calls across multiple modules, visualize call hierarchies, and generate execution time reports.
Key features of pyftrace include:
- Function Call/Return Tracing: Monitor calls/returns to functions in your Python script and imported modules.
- Built-in Function Tracing: Optionally trace built-in functions like
printusing the--verboseflag. - Multiple Module Support: Trace functions across multiple files within your project.
- Execution Reports: Generate reports detailing function execution times and call counts with the
--reportflag. - Path Tracing: Trace the path of traced Python file using the
--pathflag. - TUI Mode: Run pyftrace in a Text User Interface (TUI) mode using the
tuicommand.
$ pyftrace --help
usage: pyftrace [options] [tui] script [script_args ...]
pyftrace: Python function tracing tool.
positional arguments:
script Path to the script to run and trace. Specify 'tui' before the script path to run in TUI mode.
options:
-h, --help show this help message and exit
-V, --version Show the version of pyftrace and exit
-v, --verbose Enable built-in and third-party function tracing
-p, --path Show file paths in tracing output
-r, --report Generate a report of function execution times
- Python Version: pyftrace requires Python 3.12 or higher due to its use of the new
sys.monitoringmodule introduced in Python 3.12.
$ pyftrace [options] /path/to/python/script.py$ git clone https://github.com/kangtegong/pyftrace.git
$ cd pyftrace
$ pip install -e .
or
$ pip install pyftrace
note: on Windows, windows-curses is required.
--reportor-r: Generate a report of function execution times and call counts at the end of the script's execution.--verboseor-v: Enable tracing of built-in functions (e.g., print, len). Without this flag, pyftrace only traces user-defined functions.--pathor-p: Include file paths in the tracing output.--helpor-h: Display help information about pyftrace and its options.--versionor-V: Display help information about pyftrace and its options.
To run pyftrace in TUI(Text User Interface) mode, use the tui command before the script path.
pyftrace [options] tui path/to/your_script.py↑or↓: Scroll up or down one line at a time.PgUporPgDn: Scroll up or down one page at a time.HomeorEnd: Jump to the beginning or end of the trace.←or→: Scroll left or right horizontally.q: Quit the TUI mode.
The examples/ directory contains a variety of Python files that can be traced using pyftrace.
In this example, main_script.py imports and calls functions from module_a.py and module_b.py. We'll use pyftrace to trace these function calls and understand the flow of execution.
# module_a.py
1 def function_a():
2 print("Function A is called.")
3 return "ret_a"# module_b.py
1 def function_b():
2 print("Function B is called.")
3 return "ret_b"# main_script.py
1 from module_a import function_a
2 from module_b import function_b
3
4 def main():
5 result_a = function_a()
6 result_b = function_b()
7 print(f"Results: {result_a}, {result_b}")
8
9 if __name__ == "__main__":
10 main()To trace function calls in main_script.py without including built-in functions or file paths:
$ pyftrace examples/module_trace/main_script.py
output:
Running script: examples/module_trace/main_script.py
Called main from line 10
Called function_a from line 5
Function A is called.
Returning function_a-> ret_a
Called function_b from line 6
Function B is called.
Returning function_b-> ret_b
Results: ret_a, ret_b
Returning main-> None
Returning <module>-> None
$ pyftrace --verbose examples/module_trace/main_script.py
output:
Running script: examples/module_trace/main_script.py
Called main from line 10
Called function_a from line 5
Called print from line 2
Function A is called.
Returning print
Returning function_a-> ret_a
Called function_b from line 6
Called print from line 2
Function B is called.
Returning print
Returning function_b-> ret_b
Called print from line 7
Results: ret_a, ret_b
Returning print
Returning main-> None
Returning <module>-> None
$ pyftrace --path examples/module_trace/main_script.py
In this case, When a function is called, pyftrace displays it in the following format:
Called {function} @ {defined file path}:{defined line} from {called file path}:{called line}
{function}: name of the function being called{defined file path}: file path where the function is defined (enabled with--pathoption){defined line}" line number in the defined file{called line}line number in the calling file{called file path}path to the file that contains the calling function (enabled with--pathoption)
output:
Running script: examples/module_trace/main_script.py
Called main@examples/module_trace/main_script.py:4 from examples/module_trace/main_script.py:10
Called function_a@examples/module_trace/module_a.py:1 from examples/module_trace/main_script.py:5
Function A is called.
Returning function_a-> ret_a @ examples/module_trace/module_a.py
Called function_b@examples/module_trace/module_b.py:1 from examples/module_trace/main_script.py:6
Function B is called.
Returning function_b-> ret_b @ examples/module_trace/module_b.py
Results: ret_a, ret_b
Returning main-> None @ examples/module_trace/main_script.py
Returning <module>-> None @ examples/module_trace/main_script.py
To generate a summary report of function execution times and call counts:
$ pyftrace --report examples/module_trace/main_script.py
output:
Running script: examples/module_trace/main_script.py
Function A is called.
Function B is called.
Results: ret_a, ret_b
Function Name | Total Execution Time | Call Count
---------------------------------------------------------
main | 0.000082 seconds | 1
function_a | 0.000022 seconds | 1
function_b | 0.000008 seconds | 1
To trace built-in functions and include file paths:
$ pyftrace --verbose --path examples/module_trace/main_script.py
$ pyftrace -vp examples/module_trace/main_script.py
output:
Running script: examples/module_trace/main_script.py
Called main@examples/module_trace/main_script.py:4 from examples/module_trace/main_script.py:10
Called function_a@examples/module_trace/module_a.py:1 from examples/module_trace/main_script.py:5
Called print@builtins from examples/module_trace/module_a.py:2
Function A is called.
Returning print @ examples/module_trace/module_a.py
Returning function_a-> ret_a @ examples/module_trace/module_a.py
Called function_b@examples/module_trace/module_b.py:1 from examples/module_trace/main_script.py:6
Called print@builtins from examples/module_trace/module_b.py:2
Function B is called.
Returning print @ examples/module_trace/module_b.py
Returning function_b-> ret_b @ examples/module_trace/module_b.py
Called print@builtins from examples/module_trace/main_script.py:7
Results: ret_a, ret_b
Returning print @ examples/module_trace/main_script.py
Returning main-> None @ examples/module_trace/main_script.py
Returning <module>-> None @ examples/module_trace/main_script.py
$ pyftrace --verbose --report examples/module_trace/main_script.py
$ pyftrace -vr examples/module_trace/main_script.py
output:
Running script: examples/module_trace/main_script.py
Function A is called.
Function B is called.
Results: ret_a, ret_b
Function Name | Total Execution Time | Call Count
---------------------------------------------------------
main | 0.000127 seconds | 1
print | 0.000041 seconds | 3
function_a | 0.000021 seconds | 1
function_b | 0.000016 seconds | 1
- simple-pyftrace.py is a simplified pyftrace script for the Pycon Korea 2024 presentation. It is about 100 lines of code, but has limited functionality.
MIT
See LICENSE for more infomation
pyftrace is heavily inspired by: