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SubjectRe: get_maintainer.pl produces non-deterministic results
On Wed, 11 Dec 2019 at 01:02, Joe Perches <joe@perches.com> wrote:
>
> On Tue, 2019-12-10 at 14:47 +0100, Dmitry Vyukov wrote:
> > Hi Joe,
> >
> > scripts/get_maintainer.pl fs/proc/task_mmu.c
> > non-deterministically gives me from 13 to 16 results, different number
> > every time (on upstream 6794862a). Perl v5.28.1. Michael confirmed
> > this with v5.28.2.
> > Vergard suggested to check PERL_HASH_SEED=0. Indeed it fixes
> > non-determinism. But I guess it's not the right solution, there should
> > be some logical problem.
> > My perl-fo is weak, I appreciate if somebody with proper perl-fo takes a look.
> >
> > Thanks
>
> https://lkml.org/lkml/2017/7/13/789

Right, so you can make it reproducible if you add a tie-break to the sorting:

diff --git a/scripts/get_maintainer.pl b/scripts/get_maintainer.pl
index 34085d146fa2c..109d9fb134dad 100755
--- a/scripts/get_maintainer.pl
+++ b/scripts/get_maintainer.pl
@@ -2179,7 +2179,7 @@ sub vcs_assign {
$hash{$_}++ for @lines;

# sort -rn
- foreach my $line (sort {$hash{$b} <=> $hash{$a}} keys %hash) {
+ foreach my $line (sort {$hash{$b} <=> $hash{$a} || $a cmp $b} keys %hash) {
my $sign_offs = $hash{$line};
my $percent = $sign_offs * 100 / $divisor;

This would actually favour names that start with early letters (A, B,
...) over late letters (..., Y, Z), which might also be a bad thing. I
think to fix that you could include everybody who has the same number
of signoffs at the cutoff:
diff --git a/scripts/get_maintainer.pl b/scripts/get_maintainer.pl
index 34085d146fa2c..80d3ed2ee6d70 100755
--- a/scripts/get_maintainer.pl
+++ b/scripts/get_maintainer.pl
@@ -2179,7 +2179,8 @@ sub vcs_assign {
$hash{$_}++ for @lines;

# sort -rn
- foreach my $line (sort {$hash{$b} <=> $hash{$a}} keys %hash) {
+ my $prev_sign_offs = -1;
+ foreach my $line (sort {$hash{$b} <=> $hash{$a} || $a cmp $b} keys %hash) {
my $sign_offs = $hash{$line};
my $percent = $sign_offs * 100 / $divisor;

@@ -2187,7 +2188,7 @@ sub vcs_assign {
next if (ignore_email_address($line));
$count++;
last if ($sign_offs < $email_git_min_signatures ||
- $count > $email_git_max_maintainers ||
+ ($prev_sign_offs != $sign_offs && $count >
$email_git_max_maintainers) ||
$percent < $email_git_min_percent);
push_email_address($line, '');
if ($output_rolestats) {
@@ -2196,6 +2197,8 @@ sub vcs_assign {
} else {
add_role($line, $role);
}
+
+ $prev_sign_offs = $sign_offs;
}
}

These patches are probably horribly whitespace damaged, hopefully you
get the gist of it though...

Vegard

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