One simple way to avoid recreating the sub every time is to move the lexical variables out of the loop.

my $http_code;
my $url;
my @edate;

$SIG{'__WARN__'} = sub {
  print "WARNING: ". $_[0] ."\n".
        " http_code: $http_code\n".
        " url: $url\n".
        " edate[0]: $edate[0]\n".
        " edate[1]: $edate[1]\n".
        " edate[2]: $edate[2]\n".
        " edate[3]: $edate[3]\n"
    if ($_[0] =~ /^Use of uninitialized value in hash element.*$/);
};

while (my $line = <LOG>) {
 my (@entry) = split(/\s+/, $line);
 @edate = Parse_Date(substr($entry[0],0,10));
 $http_code = substr($entry[3], -3);
 $url = "$1$2"
      if ($entry[6] =~ m|^http://.*v1=(.*)&v2=(.*)&v3=.*$|);


 $STATUS{$http_code}{$url}{$edate[0]}{$edate[1]}{$edate[2]}{$edate[3]}
+++;
}
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If you want to keep those variables from existing too far away from the loop, you can put the whole thing in a new scope.

{
  my $http_code;
  my $url;
  my @edate;

  $SIG{'__WARN__'} = sub { ... };

  while (my $line = <LOG>) {
    ...
  }
}
[download]