I work around not being able to break inside of a module before the module has finished loading by just modifying the module's source code to add $DB::single = 1; before the line I want the debugger to break at.

You can also use "b load ...". Though, I found that command to be overly picky about how you specify the file name so I patched my perl5db.pl to make it less picky:

...
sub cmd_b_load {
    my $file = shift;
    my @files;

    $file =~ s!::!/!g;   # Added this line
...
    $signal = 1, print $OUT "'$filename' loaded...\n"
#     if $break_on_load{$filename};  # Replaced this line with the fol
+lowing:
      if grep $break_on_load{$_}, $filename =~ m{(?:^|[/\\])(?=(.*))}g
+;
...
[download]

$ perlbrew use 5.18.2t

$ perl -d -E'
   BEGIN {
      say ${^GLOBAL_PHASE};
      $DB::single = 1;
      say "Hi";
   }
'

Loading DB routines from perl5db.pl version 1.39_10
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

START
main::CODE(0x16bda48)(-e:5):          say "Hi";
  DB<1> r
Hi
void context return from CODE(0x16bda48)
Debugged program terminated.  Use q to quit or R to restart,
use o inhibit_exit to avoid stopping after program termination,
h q, h R or h o to get additional info.
  DB<1> q
[download]

Since this is a custom debugger written from scratch, it's a tricky task, but i'll do my best

For now i can say that GLOBAL_PHASE seems not to be an issue here.

Small explanation of what i'm trying to do:

1. We have an IDE with some Perl project. Breakpoints set in several files using IDE.
2. On start of debugging session, IDE sends all breakpoints to the debugger.
3. On each invocation of DB::sub/DB::postponed debugger checks list of already loaded files and attempts to set queued breakpoins. On success it informs IDE about it.
4. On each invocation of DB::DB debugger goes to interactive mode and awaits commands from IDE. Breakpoints may be set here in interactive mode.

Everything works as intended in Strawberry 5.22.2, but in Ubuntu 5.18.2 breakpoints set in step 3 are ignored. But, if file already been loaded, you've step in and you set a breakpoint in interactive mode, they works fine.

It looks like breakpoint works only if its been set from DB::DB invoked from breakpoint's target file. But sounds too stupid.

> Since this is a custom debugger written from scratch

I'm irritated ... you are using perl5db.pl terminology but you wrote a new debugger from scratch?

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!}