smallprof(3)
NAME
Devel::SmallProf - per-line Perl profiler
SYNOPSIS
perl5 -d:SmallProf test.pl
DESCRIPTION
- The Devel::SmallProf profiler is focused on the time taken
for a program run on a line-by-line basis. It is intended
to be as "small" in terms of impact on the speed and mem
ory usage of the profiled program as possible and also in
terms of being simple to use. Those statistics are placed
in the file smallprof.out in the following format: - <num> <time> <ctime> <line>:<text>
- where <num> is the number of times that the line was exe
cuted, <time> is the amount of "wall time" (time according
the the clock on the wall vs. cpu time) spent executing
it, <ctime> is the amount of cpu time expended on it and
<line> and <text> are the line number and the actual text
of the executed line (read from the file). - The package uses the debugging hooks in Perl and thus
needs the -d switch, so to profile test.pl, use the com mand:
perl5 -d:SmallProf test.pl- Once the script is done, the statistics in smallprof.out
can be sorted to show which lines took the most time. The
output can be sorted to find which lines take the longest,
either with the sort command:
sort -k 2nr,2 smallprof.out | less- or a perl script:
open(PROF,"smallprof.out");
@sorted = sort {(split(/,$b))[2] <=>(split(/,$a))[2]} <PROF>;- close PROF;
print join('',@sorted);
NOTES
- · The "wall time" readings come from Time::HiRes and are
- reasonably useful, at least on my system. The cpu
times come from the 'times' built-in and the granular
ity is not necessarily as small as with the wall time.
On some systems this column may be useful. On others
it may not. - · SmallProf does attempt to make up for its shortcomings
- by subtracting a small amount from each timing (null
time compensation). This should help somewhat with
the accuracy. - · SmallProf depends on the Time::HiRes package to do its
- timings. It claims to require version 1.20, but may
work with earlier versions, depending on your
platform.
OPTIONS
SmallProf has 3 variables which can be used during your
script to affect what gets profiled.
- · If you do not wish to see lines which were never
- called, set the variable "$DB::drop_zeros = 1". With
"drop_zeros" set, SmallProf can be used for basic cov
erage analysis. - · To turn off profiling for a time, insert a "$DB::pro
- file = 0" into your code (profiling may be turned back
on with "$DB::profile = 1"). All of the time between
profiling being turned off and back on again will be
lumped together and reported on the "$DB::profile = 0"
line. This can be used to summarize a subroutine call
or a chunk of code. - · To only profile code in a certain package, set the
- "%DB::packages" array. For example, to see only the
code in packages "main" and "Test1", do this:
%DB::packages = ( 'main' => 1, 'Test1' => 1 ); - · These variables can be put in a file called .smallprof
- in the current directory. For example, a .smallprof
containing
$DB::drop_zeros = 1;
$DB::profile = 0; - will set SmallProf to not report lines which are never
touched for any file profiled in that directory and
will set profiling off initially (presumably to be
turned on only for a small portion of code).
INSTALLATION
- Just the usual
- perl Makefile.PL
make
make test
make install - and should install fine via the CPAN module.
BUGS
Subroutine calls are currently not under the control of
%DB::packages. This should not be a great inconvenience
in general.
The handling of evals is bad news. This is due to Perl's
handling of evals under the -d flag. For certain evals,
caller() returns '(eval n)' for the filename and for oth
ers it doesn't. For some of those which it does, the
array "@{'_<filename'}" contains the code of the eval.
For others it doesn't. Sometime, when I've an extra tuit
or two, I'll figure out why and how I can compensate for
this. (Note: 5.6.0 made some debugging changes. This may
now be fixed, I'm not sure).
SmallProf must be invoked from the command line. If it is
included on the shebang line, the file in which it is
included will not be visible in the symbol table.
Profiling will continue as expected, but the contents of
the source lines will not be listed. This is new as of
5.6.0.
Comments, advice and questions are welcome. If you see
inefficent stuff in this module and have a better way,
please let me know.
AUTHOR
Ted Ashton <ashted@southern.edu>
SmallProf was developed from code originally posted to
usenet by Philippe Verdret <philippe.verdret@sonovisionitep.fr>. Special thanks to Geoffrey Broadwell <habu
san2@sprynet.com> for his assistance on the Win32 platform
and to Philippe for his patient assistance in testing and
debugging.
Copyright (c) 1997 Ted Ashton
This module is free software and can be redistributed
and/or modified under the same terms as Perl itself.
SEE ALSO
- the Devel::DProf manpage, the Time::HiRes manpage.