From 8d56af377c158823497df17b2ef18637bbc11a1c Mon Sep 17 00:00:00 2001
From: Mason James <mtj@kohaaloha.com>
Date: Mon, 29 Jun 2020 13:40:36 +1200
Subject: [PATCH] Bug 25889: Increase performance of debian/list-deps script

to test... (on a i7-2600 vm with 8 cores)

1/ run script, note execution time
    $ time ./debian/update-control
    real    8m5.000s

2/ copy old file
    $ cp ./debian/control control.old

3/ apply patch

4/ run updated script, note execution time is smaller
    $ time ./debian/update-control
    real    2m14.000s

5/ copy new file
    $ cp ./debian/control control.new

6/ confirm old and new control files are identical
    $ diff control.old control.new | wc -l
    0

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
---
 debian/list-deps | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/debian/list-deps b/debian/list-deps
index 4bf9367df1..68f3b60806 100755
--- a/debian/list-deps
+++ b/debian/list-deps
@@ -18,6 +18,8 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 use Modern::Perl;
+use Parallel::ForkManager;
+use Sys::CPU;
 
 use C4::Installer::PerlModules;
 
@@ -42,15 +44,22 @@ my %ignore = (
 
 my $prefix = "^/usr/((lib|share)/perl5|(lib|share)/perl/[0-9.]+|(lib|share)/.*-linux-gnu.*/perl/[0-9.]+|(lib|share)/.*-linux-gnu.*/perl5/[0-9.]+)";
 
+my $pm   = new Parallel::ForkManager( Sys::CPU::cpu_count() );
+
 my $modules = C4::Installer::PerlModules->new();
 my $prereqs = $modules->prereqs;
 foreach my $phase ($prereqs->phases) {
     foreach my $type ($prereqs->types_in($phase)) {
         my $reqs = $prereqs->requirements_for($phase, $type);
+
+        MODULE_LOOP:
         foreach my $module ( $reqs->required_modules ) {
+            my $pid = $pm->start and next MODULE_LOOP;
+
             next if $ignore{$module};
             my $subpath = $module;
             $subpath =~ s,::,/,g;
+
             my $output = qx(apt-file -l -x search "$prefix/$subpath.pm\$");
             my @temp   = split( /\n/, $output );
             my @lines  = ();
@@ -83,18 +92,7 @@ foreach my $phase ($prereqs->phases) {
                 print "\n";
             }
             elsif ( scalar(@temp) != 0 ) {
-
-                # I'm an Essential and I'm OK,
-                # I install all night, and work all day.
-                # I chomp up strings. I eat my bugs.
-                # I go to the base install.
-                # On Fridays I go drinking,
-                # and have buttered commits for git.
-                # (Beer O'Clock is more than two hours
-                # away. I don't even drink beer. There
-                # is no reason to be suspicious of this
-                # commit.)
-                # RM note: suspicious?  me?  always!
+                # hmm, skip module
             }
             elsif ( $type ne 'requires' ) {
                 # Ignore because we don't have it and we don't care.
@@ -102,6 +100,9 @@ foreach my $phase ($prereqs->phases) {
             else {
                 print "EEEK: unknown package for $module\n";
             }
+
+            $pm->finish; # Terminates the child process
         }
     }
 }
+$pm->wait_all_children;
-- 
2.39.5