I tweaked you code a little to get a view of what was happening:

  my $rcvd = 0 ;     # added counter for signals seen in eval's handle
+r

  sub wrap_sigs {
...
    eval {
      for my $sig (keys %$signals) {
        $old_sighandlers{$sig} = ($SIG{$sig} || 'DEFAULT');
        $SIG{$sig} =  sub { $rcvd++ ; die ("SIG $sig $rcvd\n") };
...

[download]
and the result was:
1..1
# parent entering wrap_sigs loop
# child starting signal storm
SIG ALRM 5
# Looks like your test died before it could output anything.
from which I conclude that a number of ALRM signals were trapped in the eval, but eventually Perl left eval state, with the die handler still set.

Running the thing a number of times I got quite a wide range of numbers of ALRM signals swallowed while in the eval.

In reply to Re^3: Setting signal handlers considered unsafe? by gone2015
in thread Setting signal handlers considered unsafe? by gnosek

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