my @retCodes_values;

open my $read_log_file, '<', '/tmp/app.log' or die $!;

while(<$read_log_file>){
next unless /retCode\=/;
   my ($string, $exit_code) = split /retCode\=/,$_,2;
   push @retCodes_values, [ $string, $exit_code ];
}

foreach(@retCodes_values) {

if ($_!=~3) {

read 2nd log file;
read 3rd log file;

}
}