Devel::SmallProf - per-line Perl profiler

            perl5 -d:SmallProf

    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 memory 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> <file>:<line>:<text>

    where <num> is the number of times that the line was executed,
    <time> is the amount of time spent executing it and <file>,
    <line> and <text> are the filename, 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, use the command:

            perl5 -d:SmallProf

    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:

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

    *   The timings are made with "wall time" (time in real life vs. cpu
        usage). I'd like eventually to report cpu time, but that
        isn't terribly easy to get across platforms.

    *   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
        except for the Win32 version which depends on Win32::API.

    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 coverage analysis.

    *   To turn off profiling for a time, insert a `$DB::profile = 0'
        into your code (profiling may be turned back on with
        `$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).

    Just the usual

            perl Makefile.PL
            make test
            make install

    and should install fine via the CPAN module. Makefile.PL checks
    to see if this is a Win32 platform and runs a conversion
    subroutine on SmallProf prior to installation.

    Subroutine calls are currently not under the control of
    %DB::packages. This should not be a great inconvenience in

    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 others 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.

    Comments, advice and questions are welcome. If you see
    inefficent stuff in this module and have a better way, please
    let me know.

Ted Ashton <>
SmallProf was developed from code originally posted to usenet by Philippe
Verdret <>.  Special thanks to
Geoffrey Broadwell <> for the Win32 code.
Copyright (c) 1997 Ted Ashton
This module is free software and can be redistributed and/or modified under the
same terms as Perl itself.
    the Devel::DProf manpage, the Time::HiRes manpage, the
    Win32::API manpage