As an alternative to copying the hash every time, I'd prefer to ditch the global variable and pass a hash reference to all the subroutines (depending on the size of the hash, it could be worthwhile efficiency-wise), something like:

:

while($not_done) {
 my %hash;
 sub1(\%hash);
 sub2(\%hash);
 push @AoH, \%hash;
}

sub sub1 {
 my $href=shift;
 $href->{key}="value";
}

sub sub2 {
 my $href = shift;
 # Mess with href some more
}
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