Another possibility is sending the result to the manager process via MCE->gather. MCE::Candy provides an ordered output iterator.

Unlike the previous demonstration, this one doesn't require MCE 1.830 minimally.

#!/usr/bin/perl

use strict;
use warnings;

use MCE::Loop;
use MCE::Candy;

my $mbnum = $ARGV[0] or die "usage: $0 mbnum\n";

my @ldif_files = qw(
    /path/to/file1.ldif.bz2
    /path/to/file2.ldif.bz2
    /path/to/file3.ldif.bz2
);

MCE::Loop->init(
    chunk_size => 1, max_workers => scalar @ldif_files,
    gather => MCE::Candy::out_iter_fh(\*STDOUT)
);

mce_loop {
    my ($mce, $chunk_ref, $chunk_id) = @_;
    my ($file, $ret) = ($chunk_ref->[0], '');

    # Must localize $/ to not stall MCE, fixed in 1.830.
    # Localizing $/ is recommended, but fixed MCE if not.

    local $/ = "";

    open my $fh, "-|", "/usr/bin/bzcat $file"
        or warn "open error ($file): $!";

    if (defined fileno($fh)) {
        while (<$fh>) {
            if (/uid=$mbnum/m) {
                $ret  = "## $file\n";
                $ret .= $_;
                last;
            }
        }
        close $fh;
    }

    # The out_iter_fh iterator wants the chunk_id value.
    # Thus, all participating workers must call gather once only.
    # The manager process outputs the value for chunk_id 1 first,
    # then chunk_id 2, et cetera.

    MCE->gather($chunk_id, $ret);

} \@ldif_files;

MCE::Loop->finish;

[download]

Regards, Mario

In reply to Re^6: Searching large files a block at a time by marioroy
in thread Searching large files a block at a time by JediWombat

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