dbush has asked for the wisdom of the Perl Monks concerning the following question:

I am currently doing some performance tuning and have a question regarding the output of Dprofpp. I am seeing that the majority of time (40% or more) is being taken up with many thousands of calls to main::BEGIN.

The typical output that I'm getting looks like this:

> dprofpp Total Elapsed Time = -51.0824 Seconds User+System Time = 310.7123 Seconds Exclusive Times %Time ExclSec CumulS #Calls sec/call Csec/c Name 44.8 139.2 114.05 843865 0.0000 0.0000 main::BEGIN 31.3 97.53 97.452 36407 0.0027 0.0027 DBI::st::execute 22.4 69.62 183.55 4 17.405 45.889 main::ScanBuffer Snip...

I had a super search and a look on CPAN. I found the following useful:

  • The CPAN documentation at Devel::DProf
  • Wierd dprofpp results. by dreadpiratepeter
  • The followup by dug seems to indicate that Dprof may be lying but... is it?
  • With Why is perl spending so much time in the BEGIN section? by erabus I thought I had cracked it but... I'm not sure that really answers it. I do not have a BEGIN {} block in my script.
  • One further thing that might be useful are the modules that I'm using:

    use strict; use DBI qw(:sql_types); use Data::Dumper;

    ... I mention this as I think the BEGIN block is called by AUTOLOADER when use-ing modules but I'm afraid that I'm not very clear on the details. One thought that I had was that Dprof was counting the BEGIN blocks in the imported modules but not labelling them correctly in the output. Plausible or not?