NAME
    Devel::SmallProf - a small Perl profiler

SYNOPSIS
            perl5 -d:SmallProf test.pl

DESCRIPTION
    The Devel::SmallProf is a small profiler which I find useful (or at
    least interesting :-) when used in conjuction with Devel::DProf. It
    collects statistics on the run times of the lines in the various files
    being run. Those statistics are placed in the file smallprof.out in one
    of two formats. If `$DB::print_lines' is false (the default), it prints:

            <num> <time> <file>:<line>

    where <num> is the number of times that the line was executed, <time> is
    the amount of time spent executing it and <file> and <line> are the
    filename and line number, respectively.

    If, on the other hand, `$DB::print_lines' is true, it print:

            <num> <time> <text>

    where <num> and <time> are as above and <text> is the actual text of the
    executed line (read from the file). If the executed line, however, is in
    an eval, no line is printed.

    The package uses the debugging hooks in Perl and thus needs the -d
    switch, so to profile test.pl, use the command:

            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 -nrk 2 smallprof.out | less

    or a perl script:

            open(PROF,"smallprof.out");
            @sorted = sort {(split(/\s+/,$b))[2] <=> 
                            (split(/\s+/,$a))[2]} <PROF>;
            close PROF;
            print join('',@sorted);

NOTES
    *   Determining the accuracy or signifiance of the results is left as an
        exercise for the reader. I've tried to keep the timings pretty much
        just to the profiled code, but no guarantees of any kind are made.

    *   SmallProf depends on `syscall()' and `gettimeofday()' (see the "syscall"
        entry in the perlfunc manpage) to do its timings. If your system
        lacks them SmallProf won't work.

    *   There is a variable called `$DB::profile_evals' which sets up some code
        to try to help the programmer evaluate *which* eval is taking all
        the time. You can activate this code by putting a
        `BEGIN{$DB::profile_evals =1}' at the beginning of your script. It
        is not clear whether this should be considered a feature or a bug.
        See the section on "BUGS".

BUGS
    The handling of evals is poor. The results, even with
    `$DB::profile_evals' on, are ugly. The code to handle
    `$DB::profile_evals' is even uglier. The eval profiling uses the
    `@{"main::_<$filename"}' array to find the code which is currently being
    executed. I expect that things could be improved somewhat by dealing
    appropriately with packages, but the reference in the perldebug manpage
    calls it only `@{"_<$filename"}'. As it is, the eval lines reported are
    blank some of the time. Even when they show up, it can be hard to tell
    where they originated.

    Also, there has got to be a better way to switch that stuff on and off
    than "bootstrapping" `&DB::DB'. If there is a slick, computationally
    cheap way of dealing with evals, I'm intending to set it to always debug
    evals and try to forget that I ever wrote kludge that is there now, but
    it's there now because I'm trying to keep the expense of this module as
    low as possible.

    Comments, advice and insulting remarks about kludges 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 orignally posted to usenet by Philippe
    Verdret. I've attempted to contact him but have had no success.

    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 gettimeofday() manpage