pycallgraph : usage example

'pycallgraph' is a fine python utility enabling developers to prepare call graph for any python code piece... it also notifies the number of times a call being made and total time spent in it

Homepage: http://pycallgraph.slowchop.com/pycallgraph/wiki
Codebase: https://github.com/gak/pycallgraph

it require 'graphviz' (http://www.graphviz.org/) to be present on the same machine for image generation from the analyzed calls data...

install : $ pip install pycallgraph

Usage#1 Selective graphing

wrap the code to be graphed as follows...

import pycallgraph
pycallgraph.start_trace()
fetch() # logic to be graphed
pycallgraph.stop_trace()
just_log() # logic NOT to be graphed
pycallgraph.start_trace()
process() # logic to be graphed
pycallgraph.stop_trace()
pycallgraph.make_dot_graph('path_to_graph.png')

Usage#2 Decorator

Import the decorator method and place the decorator over any method where call graph is required...
import this file wherever you require the @callgraph decorator and use it

Decorator Python code. Sample code with decorator usage and selective trace usage are at end of this blog... from this gist: https://gist.github.com/abhishekkr/5592520



pycallgraph.start_trace() method lets you pass a filter function to not graph some modules on purpose, say in nova I don't wanna graph all the dependency libraries magical calls...


STATUTORY WARNING: Graph will be huge for a very high level call and probably unreadable due to overworked image generator. Use it wisely on burnt areas.


Call Graph images for code sample in Gists

for call with decorator



for call with selective trace

	#!/usr/bin/env python
	"""
	require 'pycallgraph' library to be installed with graphviz,
	and the attached "pycallgraph_decorator.py" file to be present as well
	to provide the decorator used
	"""
	from pycallgraph_decorator import callgraph
	def add(arg1, arg2):
	return (arg1 + arg2)
	def mul(arg1, arg2):
	return (arg1 * arg2)
	def say(msg):
	print("[+] %s" % msg)
	@callgraph()
	def add_n_mul(arg1, arg2):
	add_val = add(arg1, arg2)
	say("just a sample meth o d")
	mul_val = mul(arg1, arg2)
	return (add_val, mul_val)
	print(add_n_mul(5, 10))

view raw decorated_sample01.py hosted with ❤ by GitHub

	import pycallgraph
	"""
	Let's you use PyCallGraph as a decorator
	"""
	def callgraph():
	def argwrapper(func):
	def callwrapper(*args, **kwargs):
	if callwrapper.already_called:
	return func(*args, **kwargs)
	callwrapper.already_called = True
	pycallgraph.start_trace(reset = False)
	result = func(*args, **kwargs)
	pycallgraph.stop_trace()
	filename = "/tmp/%s.png" % str(func.__name__)
	pycallgraph.make_dot_graph(filename) #, format='jpg') #, tool='neato')
	return result
	callwrapper.already_called = False
	return callwrapper
	return argwrapper

view raw pycallgraph_decorator.py hosted with ❤ by GitHub

	#!/usr/bin/env python
	"""
	require just 'pycallgraph' library to be installed with graphviz, all tracing code is present inline
	"""
	import pycallgraph
	def add(arg1, arg2):
	return (arg1 + arg2)
	def mul(arg1, arg2):
	return (arg1 * arg2)
	def say(msg):
	print("[+] %s" % msg)
	def add_n_mul(arg1, arg2):
	pycallgraph.start_trace()
	add_val = add(arg1, arg2)
	pycallgraph.stop_trace()
	say("just a sample meth o d")
	pycallgraph.start_trace(reset = False)
	pycallgraph.call_stack.pop() # to get 'add__mul' as parent of current calls again
	mul_val = mul(arg1, arg2)
	pycallgraph.stop_trace()
	pycallgraph.make_dot_graph('/tmp/selective_add_n_mul.png')
	return (add_val, mul_val)
	print(add_n_mul(5, 10))

view raw selective_call_graph_sample02.py hosted with ❤ by GitHub