chemicalchecker.util.decorator.profilehooks

Profiling hooks.

This module contains a couple of decorators (profile and coverage) that can be used to wrap functions and/or methods to produce profiles and line coverage reports. There’s a third convenient decorator (timecall) that measures the duration of function execution without the extra profiling overhead.

Usage example (Python 2.4 or newer):

from profilehooks import profile, coverage

@profile    # or @coverage
def fn(n):
    if n < 2: return 1
    else: return n * fn(n-1)

print(fn(42))

Or without imports, with some hack

$ python -m profilehooks yourmodule

@profile # or @coverage def fn(n):

if n < 2: return 1 else: return n * fn(n-1)

print(fn(42))

Usage example (Python 2.3 or older):

from profilehooks import profile, coverage

def fn(n):
    if n < 2: return 1
    else: return n * fn(n-1)

# Now wrap that function in a decorator
fn = profile(fn) # or coverage(fn)

print fn(42)

Reports for all thusly decorated functions will be printed to sys.stdout on program termination. You can alternatively request for immediate reports for each call by passing immediate=True to the profile decorator.

There’s also a @timecall decorator for printing the time to sys.stderr every time a function is called, when you just want to get a rough measure instead of a detailed (but costly) profile.

Caveats

A thread on python-dev convinced me that hotshot produces bogus numbers. See https://mail.python.org/pipermail/python-dev/2005-November/058264.html

I don’t know what will happen if a decorated function will try to call another decorated function. All decorators probably need to explicitly support nested profiling (currently TraceFuncCoverage is the only one that supports this, while HotShotFuncProfile has support for recursive functions.)

Profiling with hotshot creates temporary files (*.prof for profiling, *.cprof for coverage) in the current directory. These files are not cleaned up. Exception: when you specify a filename to the profile decorator (to store the pstats.Stats object for later inspection), the temporary file will be the filename you specified with ‘.raw’ appended at the end.

Coverage analysis with hotshot seems to miss some executions resulting in lower line counts and some lines errorneously marked as never executed. For this reason coverage analysis now uses trace.py which is slower, but more accurate.

Released under the MIT licence since December 2006:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

(Previously it was distributed under the GNU General Public Licence.)

Functions

`coverage`	Mark fn for line coverage analysis.
`coverage_with_hotshot`	Mark fn for line coverage analysis.
`profile`	Mark fn for profiling.
`timecall`	Wrap fn and print its execution time.

Classes

`CProfileFuncProfile`	Profiler for a function (uses cProfile).
`FuncProfile`	Profiler for a function (uses profile).
`FuncSource`	Source code annotator for a function.
`FuncTimer`
`TraceFuncCoverage`	Coverage analysis for a function (uses trace module).