Question

I’ve recently been working on some code to catch errors throughout our code base (I.E. do a try/catch at the very top level of our Perl code). To my distress, I find that Perl stack traces omit stack frames! Gaaa! I’m looking for insight into why these stack frames are gone. The documentation for caller() says stack frames can be ‘optimized away’. But really, it’s so annoying to have them gone. Is there a way to coax Perl into including them? Is there a performance penalty for doing so? Below is a trivial example. As you will see, neither bar() nor bletch() are included in the stack trace. A sad omission that causes me to have to trace the code by hand.

Any insights received with gratitude.

Leonard

Here is foo.pl

use strict;
use warnings;

use Devel::StackTrace;
use Try::Tiny;

foo();

sub foo {
    print "In foo\n";
    try {
        bar();
    }
    catch {
        my $trace = Devel::StackTrace->new();
        print $trace->as_string;
    };
}

sub bar {
    print "In bar\n";
    bletch();
    my $more_stuff = 123;
    return $more_stuff;
}

sub bletch {
    print "In bletch\n";
    my $not_so_defined;
    $not_so_defined->barf();
    print "Unlikely to be printed\n";

}

And here is what gets printed when foo.pl is run:

In foo
In bar
In bletch
Trace begun at foo.pl line 17
main::__ANON__('Can\'t call method "barf" on an undefined value at ./foo.pl line 32.^J') called at /vcm/home/apps/perl-5.12.1/lib/site_perl/5.12.1/Try/Tiny.pm line 100
Try::Tiny::try('CODE(0xf503a0)', 'Try::Tiny::Catch=REF(0x1035ca0)') called at foo.pl line 19
main::foo at foo.pl line 9

Answer 1

Below is a trivial example. As you will see, neither bar() nor bletch() are included in the stack trace.

Yeah, because you’ve exited bar and bletch before getting the stack trace.

Create a $SIG{__DIE__} handler.