Lots of small markup adjustments.

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Fred Drake 2003-04-09 04:06:37 +00:00
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High performance logging profiler} High performance logging profiler}
\declaremodule{standard}{hotshot} \declaremodule{standard}{hotshot}
\modulesynopsis{High performance logging profiler, mostly written in C.}
\moduleauthor{Fred L. Drake, Jr.}{fdrake@acm.org} \moduleauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
\sectionauthor{Anthony Baxter}{anthony@interlink.com.au} \sectionauthor{Anthony Baxter}{anthony@interlink.com.au}
\versionadded{2.2} \versionadded{2.2}
\modulesynopsis{High performance logging profiler, mostly written in C.}
This module provides a nicer interface to the \module{_hotshot} C module.
This module provides a nicer interface to the \code{_hotshot} C module.
Hotshot is a replacement for the existing \refmodule{profile} module. As it's Hotshot is a replacement for the existing \refmodule{profile} module. As it's
written mostly in C, it should result in a much smaller performance impact written mostly in C, it should result in a much smaller performance impact
than the existing profile module. than the existing \refmodule{profile} module.
\begin{classdesc}{Profile}{logfile, \optional{, lineevents=0, linetimings=1}} \begin{classdesc}{Profile}{logfile\optional{,
lineevents\code{=0}\optional{,
The profiler object. The argument \var{logfile} is the name of a log file linetimings\code{=1}}}}
to use for logged profile data. The argument \var{lineevents} specifies whether The profiler object. The argument \var{logfile} is the name of a log
to generate events for every source line, or just on function call/return. It file to use for logged profile data. The argument \var{lineevents}
defaults to 0 (only log function call/return). The argument \var{linetimings} specifies whether to generate events for every source line, or just on
specifies whether to record timing information. It defaults to 1 (store timing function call/return. It defaults to \code{0} (only log function
call/return). The argument \var{linetimings} specifies whether to
record timing information. It defaults to \code{1} (store timing
information). information).
\end{classdesc} \end{classdesc}
\subsection{Profile Objects \label{hotshot-objects}} \subsection{Profile Objects \label{hotshot-objects}}
Profile objects have the following methods: Profile objects have the following methods:
@ -39,21 +39,18 @@ Add an arbitrary labelled value to the profile output.
Close the logfile and terminate the profiler. Close the logfile and terminate the profiler.
\end{methoddesc} \end{methoddesc}
%
\begin{methoddesc}{fileno}{} \begin{methoddesc}{fileno}{}
Return the file descriptor of the profiler's log file. Return the file descriptor of the profiler's log file.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}{run}{cmd} \begin{methoddesc}{run}{cmd}
Profile an exec-compatible string in the script environment. Profile an \keyword{exec}-compatible string in the script environment.
The globals from the \refmodule[main]{__main__} module are used as
The globals from the \module{__main__} module are used as
both the globals and locals for the script. both the globals and locals for the script.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}{runcall}{func, *args, **keywords} \begin{methoddesc}{runcall}{func, *args, **keywords}
Profile a single call of a callable. Profile a single call of a callable.
Additional positional and keyword arguments may be passed Additional positional and keyword arguments may be passed
along; the result of the call is returned, and exceptions are along; the result of the call is returned, and exceptions are
allowed to propogate cleanly, while ensuring that profiling is allowed to propogate cleanly, while ensuring that profiling is
@ -62,8 +59,7 @@ disabled on the way out.
\begin{methoddesc}{runctx}{cmd, globals, locals} \begin{methoddesc}{runctx}{cmd, globals, locals}
Evaluate an exec-compatible string in a specific environment. Evaluate an \keyword{exec}-compatible string in a specific environment.
The string is compiled before profiling begins. The string is compiled before profiling begins.
\end{methoddesc} \end{methoddesc}
@ -75,9 +71,10 @@ Start the profiler.
Stop the profiler. Stop the profiler.
\end{methoddesc} \end{methoddesc}
\subsection{Using hotshot data}
\declaremodule{standard}{hotshot.stats}
\subsection{Using hotshot data}
\declaremodule{standard}{hotshot.stats}
\modulesynopsis{Statistical analysis for Hotshot} \modulesynopsis{Statistical analysis for Hotshot}
\versionadded{2.2} \versionadded{2.2}
@ -91,16 +88,16 @@ of the \class{pstats.Stats} class.
\end{funcdesc} \end{funcdesc}
\begin{seealso} \begin{seealso}
\seemodule{profile}{The profile module's \class{Stats} class } \seemodule{profile}{The \module{profile} module's \class{Stats} class}
\end{seealso} \end{seealso}
\subsection{Example Usage \label{hotshot-example}} \subsection{Example Usage \label{hotshot-example}}
Note that this example runs the python "benchmark" pystones. It can Note that this example runs the python ``benchmark'' pystones. It can
take some time to run, and will produce large output files. take some time to run, and will produce large output files.
\begin{verbatim} \begin{verbatim}
>>> import hotshot, hotshot.stats, test.pystone >>> import hotshot, hotshot.stats, test.pystone
>>> prof = hotshot.Profile("stones.prof") >>> prof = hotshot.Profile("stones.prof")
>>> benchtime, stones = prof.runcall(test.pystone.pystones) >>> benchtime, stones = prof.runcall(test.pystone.pystones)
@ -120,7 +117,4 @@ take some time to run, and will produce large output files.
. .
. .
. .
\end{verbatim} \end{verbatim}

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@ -4,36 +4,36 @@
\declaremodule{standard}{timeit} \declaremodule{standard}{timeit}
\modulesynopsis{Measure the execution time of small code snippets.} \modulesynopsis{Measure the execution time of small code snippets.}
\versionadded{2.3}
\index{Benchmarking} \index{Benchmarking}
\index{Performance} \index{Performance}
\versionadded{2.3} This module provides a simple way to time small bits of Python code.
It has both command line as well as callable interfaces. It avoids a
number of common traps for measuring execution times. See also Tim
Peters' introduction to the ``Algorithms'' chapter in the
\citetitle{Python Cookbook}, published by O'Reilly.
This module provides a simple way to time small bits of Python code. It has The module defines the following public class:
both command line as well as callable interfaces. It avoids a number of
common traps for measuring execution times. See also Tim Peters'
introduction to the Algorithms chapter in the ``Python Cookbook'', published
by O'Reilly.
The module interface defines the following public class: \begin{classdesc}{Timer}{\optional{stmt=\code{'pass'}
\optional{, setup=\code{'pass'}
\begin{classdesc}{Timer}{\optional{stmt='pass'
\optional{, setup='pass'
\optional{, timer=<timer function>}}}} \optional{, timer=<timer function>}}}}
Class for timing execution speed of small code snippets. Class for timing execution speed of small code snippets.
The constructor takes a statement to be timed, an additional statement used The constructor takes a statement to be timed, an additional statement
for setup, and a timer function. Both statements default to 'pass'; the used for setup, and a timer function. Both statements default to
timer function is platform-dependent (see the module doc string). \code{'pass'}; the timer function is platform-dependent (see the
module doc string). The statements may contain newlines, as long as
they don't contain multi-line string literals.
To measure the execution time of the first statement, use the timeit() To measure the execution time of the first statement, use the
method. The repeat() method is a convenience to call timeit() multiple \method{timeit()} method. The \method{repeat()} method is a
times and return a list of results. convenience to call \method{timeit()} multiple times and return a list
of results.
\end{classdesc}
The statements may contain newlines, as long as they don't contain \begin{methoddesc}{print_exc}{\optional{file=\constant{None}}}
multi-line string literals.
\begin{methoddesc}{print_exc}{\optional{file=None}}
Helper to print a traceback from the timed code. Helper to print a traceback from the timed code.
Typical use: Typical use:
@ -48,20 +48,21 @@ Typical use:
The advantage over the standard traceback is that source lines in the The advantage over the standard traceback is that source lines in the
compiled template will be displayed. compiled template will be displayed.
The optional \var{file} argument directs where the traceback is sent;
The optional file argument directs where the traceback is sent; it defaults it defaults to \code{sys.stderr}.
to \code{sys.stderr}.
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}{repeat}{\optional{repeat=3\optional{, number=1000000}}} \begin{methoddesc}{repeat}{\optional{repeat\code{=3}\optional{,
number\code{=1000000}}}}
Call \method{timeit()} a few times. Call \method{timeit()} a few times.
This is a convenience function that calls the \method{timeit()} repeatedly, This is a convenience function that calls the \method{timeit()}
returning a list of results. The first argument specifies how many times to repeatedly, returning a list of results. The first argument specifies
call \function{timeit()}. The second argument specifies the \code{number} how many times to call \method{timeit()}. The second argument
argument for \function{timeit()}. specifies the \var{number} argument for \function{timeit()}.
Note: it's tempting to calculate mean and standard deviation from the result \begin{notice}
It's tempting to calculate mean and standard deviation from the result
vector and report these. However, this is not very useful. In a typical vector and report these. However, this is not very useful. In a typical
case, the lowest value gives a lower bound for how fast your machine can run case, the lowest value gives a lower bound for how fast your machine can run
the given code snippet; higher values in the result vector are typically not the given code snippet; higher values in the result vector are typically not
@ -70,25 +71,26 @@ with your timing accuracy. So the \function{min()} of the result is
probably the only number you should be interested in. After that, you probably the only number you should be interested in. After that, you
should look at the entire vector and apply common sense rather than should look at the entire vector and apply common sense rather than
statistics. statistics.
\end{notice}
\end{methoddesc} \end{methoddesc}
\begin{methoddesc}{timeit}{\optional{number=1000000}} \begin{methoddesc}{timeit}{\optional{number\code{=1000000}}}
Time \code{number} executions of the main statement. Time \var{number} executions of the main statement.
This executes the setup statement once, and then
To be precise, this executes the setup statement once, and then returns the returns the time it takes to execute the main statement a number of
time it takes to execute the main statement a number of times, as a float times, measured in seconds as a float. The argument is the number of
measured in seconds. The argument is the number of times through the loop, times through the loop, defaulting to one million. The main
defaulting to one million. The main statement, the setup statement and the statement, the setup statement and the timer function to be used are
timer function to be used are passed to the constructor. passed to the constructor.
\end{methoddesc} \end{methoddesc}
\end{classdesc}
\subsection{Command Line Interface} \subsection{Command Line Interface}
When called as a program from the command line, the following form is used: When called as a program from the command line, the following form is used:
\begin{verbatim} \begin{verbatim}
python timeit.py [-n N] [-r N] [-s S] [-t] [-c] [-h] [statement ...] python timeit.py [-n N] [-r N] [-s S] [-t] [-c] [-h] [statement ...]
\end{verbatim} \end{verbatim}
where the following options are understood: where the following options are understood:
@ -97,55 +99,64 @@ where the following options are understood:
\item[-n N/--number=N] how many times to execute 'statement' \item[-n N/--number=N] how many times to execute 'statement'
\item[-r N/--repeat=N] how many times to repeat the timer (default 3) \item[-r N/--repeat=N] how many times to repeat the timer (default 3)
\item[-s S/--setup=S] statement to be executed once initially (default \item[-s S/--setup=S] statement to be executed once initially (default
'pass') \code{'pass'})
\item[-t/--time] use time.time() (default on all platforms but Windows) \item[-t/--time] use \function{time.time()}
\item[-c/--clock] use time.clock() (default on Windows) (default on all platforms but Windows)
\item[-c/--clock] use \function{time.clock()} (default on Windows)
\item[-v/--verbose] print raw timing results; repeat for more digits \item[-v/--verbose] print raw timing results; repeat for more digits
precision precision
\item[-h/--help] print a short usage message and exit \item[-h/--help] print a short usage message and exit
\end{description} \end{description}
A multi-line statement may be given by specifying each line as a separate A multi-line statement may be given by specifying each line as a
statement argument; indented lines are possible by enclosing an argument in separate statement argument; indented lines are possible by enclosing
quotes and using leading spaces. Multiple -s options are treated similarly. an argument in quotes and using leading spaces. Multiple
\programopt{-s} options are treated similarly.
If -n is not given, a suitable number of loops is calculated by trying If \programopt{-n} is not given, a suitable number of loops is
successive powers of 10 until the total time is at least 0.2 seconds. calculated by trying successive powers of 10 until the total time is
at least 0.2 seconds.
The default timer function is platform dependent. On Windows, clock() has The default timer function is platform dependent. On Windows,
microsecond granularity but time()'s granularity is 1/60th of a second; on \function{time.clock()} has microsecond granularity but
Unix, clock() has 1/100th of a second granularity and time() is much more \function{time.time()}'s granularity is 1/60th of a second; on \UNIX,
precise. On either platform, the default timer functions measures wall \function{time.clock()} has 1/100th of a second granularity and
clock time, not the CPU time. This means that other processes running on \function{time.time()} is much more precise. On either platform, the
the same computer may interfere with the timing. The best thing to do when default timer functions measures wall clock time, not the CPU time.
accurate timing is necessary is to repeat the timing a few times and use the This means that other processes running on the same computer may
best time. The -r option is good for this; the default of 3 repetitions is interfere with the timing. The best thing to do when accurate timing
probably enough in most cases. On Unix, you can use clock() to measure CPU is necessary is to repeat the timing a few times and use the best
time. time. The \programopt{-r} option is good for this; the default of 3
repetitions is probably enough in most cases. On \UNIX, you can use
\function{time.clock()} to measure CPU time.
Note: there is a certain baseline overhead associated with executing a pass \begin{notice}
statement. The code here doesn't try to hide it, but you should be aware of There is a certain baseline overhead associated with executing a
it. The baseline overhead can be measured by invoking the program without pass statement. The code here doesn't try to hide it, but you
arguments. should be aware of it. The baseline overhead can be measured by
invoking the program without arguments.
\end{notice}
The baseline overhead differs between Python versions! Also, to fairly The baseline overhead differs between Python versions! Also, to
compare older Python versions to Python 2.3, you may want to use python -O fairly compare older Python versions to Python 2.3, you may want to
for the older versions to avoid timing SET_LINENO instructions. use Python's \programopt{-O} option for the older versions to avoid
timing \code{SET_LINENO} instructions.
\subsection{Examples} \subsection{Examples}
Here are two example sessions (one using the command line, one using the Here are two example sessions (one using the command line, one using
module interface) that compare the cost of using \function{hasattr()} the module interface) that compare the cost of using
vs. try/except to test for missing and present object attributes. \function{hasattr()} vs. \keyword{try}/\keyword{except} to test for
missing and present object attributes.
\begin{verbatim} \begin{verbatim}
\% timeit.py 'try:' ' str.__nonzero__' 'except AttributeError:' ' pass' % timeit.py 'try:' ' str.__nonzero__' 'except AttributeError:' ' pass'
100000 loops, best of 3: 15.7 usec per loop 100000 loops, best of 3: 15.7 usec per loop
\% timeit.py 'if hasattr(str, "__nonzero__"): pass' % timeit.py 'if hasattr(str, "__nonzero__"): pass'
100000 loops, best of 3: 4.26 usec per loop 100000 loops, best of 3: 4.26 usec per loop
\% timeit.py 'try:' ' int.__nonzero__' 'except AttributeError:' ' pass' % timeit.py 'try:' ' int.__nonzero__' 'except AttributeError:' ' pass'
1000000 loops, best of 3: 1.43 usec per loop 1000000 loops, best of 3: 1.43 usec per loop
\% timeit.py 'if hasattr(int, "__nonzero__"): pass' % timeit.py 'if hasattr(int, "__nonzero__"): pass'
100000 loops, best of 3: 2.23 usec per loop 100000 loops, best of 3: 2.23 usec per loop
\end{verbatim} \end{verbatim}