Re: Named anonymous subs

Wow, this is a very interesting trick. I like it a lot. But it's too bad it doesn't help DProf give useful information for anonymous subs:

use Carp;
my $i = 0;

sub foo {
     sub {
         local *__ANON__ = "local_subref_" . $i++;
         carp "blokhead";
     };
}

foo()->() for 1 .. 3;

__OUTPUT__

$ perl -d:DProf test.pl 
blokhead at test.pl line 7
        main::local_subref_0() called at test.pl line 12
blokhead at test.pl line 7
        main::local_subref_1() called at test.pl line 12
blokhead at test.pl line 7
        main::local_subref_2() called at test.pl line 12
blokhead at test.pl line 7
        main::local_subref_3() called at test.pl line 12

$ dprofpp tmon.out
Total Elapsed Time = 0.079705 Seconds
  User+System Time = 0.049705 Seconds
Exclusive Times
%Time ExclSec CumulS #Calls sec/call Csec/c  Name
 ...
 0.00       -  0.020      3        - 0.0066  main::__ANON__
 ...
[download]

Boo!! DProf still plops everything into main::__ANON__. I've run into this problem before trying to profile code that uses liberal amounts of anonymous subs, and it's quite annoying. Unfortunately I don't know enough about the internals of Perl and DProf to figure out a "clever" solution like yours that works for profiling code (other than using other *Prof modules)...

blokhead

Comment on Re: Named anonymous subs Download Code

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Re^2: Named anonymous subs by fluffy (Scribe) on Oct 02, 2004 at 18:41 UTC
As maintainer of Class::MethodMaker, I have more than a passing interest in this technique: C::MM generates anonymous routines by the bucket-load, and as well as debugging, I'm particularly interested in profiling, too. I'd been meaning to do something about this for a couple of years now, and this thread finally galvanized me into action. After two days of tinkering with it, and several false starts, I've finally come up with this XS incantation: `void set_sub_name(SV sub, char pname, char subname, char stashname) CODE: CvGV((GV)SvRV(sub)) = gv_fetchpv(stashname, TRUE, SVt_PV); GvSTASH(CvGV((GV)SvRV(sub))) = gv_stashpv(pname, 1); GvNAME(CvGV((GV)SvRV(sub))) = savepv(subname); GvNAMELEN(CvGV((GV)SvRV(sub))) = strlen(subname);` [download] The pname is the package name, the subname the subname, and stashname is the name of a stash to generate to attach the code to, to avoid overwriting the original stash (which is the package the code was compiled in), or the ANON entry in the pname stash. The above certainly appears to work, both with stack traces & the profiler, and doesn't break my code. I was concerned that generating a new stash for each subr might hurt the memory consumption, but empirical testing suggests that the effect is minimal-to-nil. I'm no XS programmer, so I'd appreciate any constructive feedback anyone has.	[reply] [d/l]
Re^3: Named anonymous subs by stvn (Monsignor) on Mar 08, 2006 at 03:22 UTC
I ran into similar issues when developing the Perl 6 metamodel stuff for Pugs, and more recently with Class::MOP. I use the Sub::Name module which has worked great for me, it is also written in XS, you might be able to get a few pointers out of the code (or better yet, just use it, why reinvent the wheel). Of course I might also be 2 years to late with this comment too :) -stvn	[reply]


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