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Full Discussion: Performance issue
Top Forums UNIX for Dummies Questions & Answers Performance issue Post 302500092 by matrixmadhan on Sunday 27th of February 2011 12:22:18 AM
Old 02-27-2011
Quote:
Originally Posted by pludi
You're probably losing most of the time on the actual output. Each call to printf costs the time of a process spawn. And the file has to be opened, written, and closed on each call.

The below Perl script creates the permutations (same number of records as in your example) in just over 2 minutes on an average sized laptop
Code:
# ./perm.pl
Thu Feb 24 15:28:41 CET 2011
Thu Feb 24 15:30:56 CET 2011
# cat perm.pl
#!/usr/bin/perl

use strict;
use warnings;

my ( $fh1, $fh2, $fh3, $out );
my ( @file1, @file2, @file3 );
system("date");
{
    local $/;
    open $fh1, '<', 'file1';
    my $file1 = <$fh1>;
    @file1 = split /\n/, $file1;
    close $fh1;
}
{
    local $/;
    open $fh2, '<', 'file2';
    my $file2 = <$fh2>;
    @file2 = split /\n/, $file2;
    close $fh2;
}
{
    local $/;
    open $fh3, '<', 'file3';
    my $file3 = <$fh3>;
    @file3 = split /\n/, $file3;
    close $fh3;
}

chomp @file1;
chomp @file2;
chomp @file3;

open $out, '>', 'file2.txt';
foreach my $first (@file1) {
    foreach my $second (@file2) {
        foreach my $third (@file3) {
            printf $out "%-9s %-9s %-9s %-9s %-9s %-9s %-9s %-9s %-9s %-9s\n",
              $first, $second, $third, 4, 5, 1, 2, 1, 5, 2;
        }
    }
}
close $out;
system("date");

---------- Post updated at 15:46 ---------- Previous update was at 15:38 ----------

Addendum: on the very same setup, the script as you have given it managed to produce ~50% of all combinations in about 17 minutes. There has to be something entirely different wrong with your setup for it to take 70 hours.
I would suggest to use perl builtin for time elapsed in seconds instead of using system call for date. But really minor.
 

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COMBINE(1)																COMBINE(1)

NAME
combine - combine sets of lines from two files using boolean operations SYNOPSIS
combine file1 and file2 combine file1 not file2 combine file1 or file2 combine file1 xor file2 _ file1 and file2 _ _ file1 not file2 _ _ file1 or file2 _ _ file1 xor file2 _ DESCRIPTION
combine combines the lines in two files. Depending on the boolean operation specified, the contents will be combined in different ways: and Outputs lines that are in file1 if they are also present in file2. not Outputs lines that are in file1 but not in file2. or Outputs lines that are in file1 or file2. xor Outputs lines that are in either file1 or file2, but not in both files. "-" can be specified for either file to read stdin for that file. The input files need not be sorted, and the lines are output in the order they occur in file1 (followed by the order they occur in file2 for the two "or" operations). Bear in mind that this means that the operations are not commutative; "a and b" will not necessarily be the same as "b and a". To obtain commutative behavior sort and uniq the result. Note that this program can be installed as "_" to allow for the syntactic sugar shown in the latter half of the synopsis (similar to the test/[ command). It is not currently installed as "_" by default, but you can alias it to that if you like. SEE ALSO
join(1) AUTHOR
Copyright 2006 by Joey Hess <joey@kitenet.net> Licensed under the GNU GPL. moreutils 2012-04-09 COMBINE(1)
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