http://www.perlmonks.org?node_id=1196701


in reply to Re^4: Searching large files a block at a time
in thread Searching large files a block at a time

Hi JediWombat,

The following provides a parallel demonstration to process all 3 LDIF files simultaneously. It requires MCE 1.830 minimally due to MCE::Relay failing from setting the input separator. That said, am posting the code before releasing 1.830 in order to have the perlmonks URL for the changelog.

Well, here is the code.

#!/usr/bin/perl use strict; use warnings; # Requires MCE 1.830. Fixes MCE::Relay stalling from setting $/. use MCE::Loop 1.830; my $mbnum = $ARGV[0] or die "usage: $0 mbnum\n"; my @ldif_files = qw( /path/to/file1.ldif.bz2 /path/to/file2.ldif.bz2 /path/to/file3.ldif.bz2 ); MCE::Loop->init( max_workers => scalar @ldif_files, chunk_size => 1, init_relay => '' ); mce_loop { # my ($mce, $chunk_ref, $chunk_id) = @_; # When chunk_size 1 is specified, $_ contains # the same value as $chunk_ref->[0]. my ($file, $ret) = ($_, ''); # 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; } # Relay is beneficial for running a code block serially # and orderly. The init_relay option enables MCE::Relay. # All participating workers must call relay. Here, workers # write to STDOUT orderly starting with chunk_id 1. MCE::relay { print $ret }; } \@ldif_files; MCE::Loop->finish;

MCE 1.830 will be released on CPAN no latter than Monday, the 7th of August. In the meantime, the MCE Github repository is current.

Regards, Mario