Update: The disparity is coming from strftime.
Update: One must use threads on the Mac and non-threads on Linux for best performance. This is mind-boggling to me. Replacing the strftime line with $A = $Y completes in a couple seconds for threads or non-threads on the Mac and Linux.
The same 500 MB input file is used by both OS.
Mac OS X Serial: 18.185s
Mac OS X Parallel: 6.687s threads
Mac OS X Parallel: 42.526s non-threads
CentOS 7 VM Serial: 10.832s
CentOS 7 VM Parallel: 23.849s threads
CentOS 7 VM Parallel: 2.993s non-threads
#!/usr/bin/perl
use strict;
use warnings;
use threads; # Comment out threads for child processes
use POSIX qw(strftime);
use MCE::Loop;
use MCE::Candy;
my $mutex :shared = 0;
my $infile = $ARGV[0];
my $outfile = $ARGV[1];
open(DATAOUT, ">", $outfile);
## Workers process chunks in parallel until completed.
## Output order is preserved via MCE::Candy::out_iter_fh
MCE::Loop::init {
chunk_size => "2m", max_workers => 4, use_slurpio => 1,
gather => MCE::Candy::out_iter_fh(\*DATAOUT)
};
mce_loop_f {
my ($mce, $chunkRef, $chunkID) = @_;
my ($output, @Fields, $X, $Y, $A, $B, $C, $D, @G) = ("");
open my $CHUNKIN, "<", $chunkRef;
while( my $line = <$CHUNKIN> )
{
chomp $line;
@Fields = split(',', $line, 9);
$X = $Fields[8];
$Y = substr $X, 0, 10;
@G = gmtime $Y;
$A = strftime "%M,%Y,%m,%d,%H,%j,%W,%u,%A", @G;
$B = substr($A, 0, index($A, ','));
$C = int($B/5);
$D = int($B/15);
$output .= $line.",$Y,$A,$C,$D\n";
}
close $CHUNKIN;
MCE->gather($chunkID, $output);
} $infile;
close(DATAOUT);