Dec 14

DTrace, Perl and TWiki – on Solaris

Tag: dtrace,new,perl,solaris,twikiSven Dowideit @ 1:36 pm

I’ve been promising myself some time to try out DTrace on TWiki’s codebase for over a year. By following Bryan Allen’s
instructions using Richard Dawe’s adaption of Alan Burlison’s work… I now have a Perl 5.8.8 with DTrace probes.

Sounds great, except for one thing…. I now have to learn enough about DTrace to use it 🙂 The patch that Alan and Richard have (or at least their DTrace scripts) seem to require a priori knowledge of the Perl process’ pid… not something thats going to work out for what I want to do.

For a quick test, DTrace -c ./view -s /export/home/sven/src/dtrace/subs-tree.d does show the program flow.

The following is while running some perl scripts – the 2 numbers are their pids.

# dtrace -l | grep -i perl
17803  perl17669        libperl.so                      Perl_pp_sort sub-entry
17804  perl17669        libperl.so                   Perl_pp_dbstate sub-entry
17805  perl17669        libperl.so                  Perl_pp_entersub sub-entry
17806  perl17669        libperl.so                      Perl_pp_last sub-return
17807  perl17669        libperl.so                    Perl_pp_return sub-return
17808  perl17669        libperl.so                     Perl_dounwind sub-return
17809  perl17669        libperl.so                Perl_pp_leavesublv sub-return
17810  perl17669        libperl.so                  Perl_pp_leavesub sub-return
88501  perl17760        libperl.so                      Perl_pp_sort sub-entry
88502  perl17760        libperl.so                   Perl_pp_dbstate sub-entry
88503  perl17760        libperl.so                  Perl_pp_entersub sub-entry
88504  perl17760        libperl.so                      Perl_pp_last sub-return
88505  perl17760        libperl.so                    Perl_pp_return sub-return
88506  perl17760        libperl.so                     Perl_dounwind sub-return
88507  perl17760        libperl.so                Perl_pp_leavesublv sub-return
88508  perl17760        libperl.so                  Perl_pp_leavesub sub-return

so… first ignorant modification – in subs-tree.d, it wants to trace perl$target:::sub-entry – change that to perl*:::sub-entry, and of course, it works exactly as I want – attaches to all subsequent perl process (running my dtrace-perl build) and tells me whats going on. The only caveat being that the DTrace script will only start if there is a Perl process running – the provider is obviously not persistent.

Brilliant!

Should be a fun Christmas holiday adventure – 410 pages of dtrace book, and a myriad of web pages to consume and digest.

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