v2writable: allow disabling parallelization

While parallel processes improves import speed for initial
imports; they are probably not necessary for daily mail imports
via WatchMaildir and certainly not for public-inbox-init.  Save
some memory for daily use and even helps improve readability of
some subroutines by showing which methods they call remotely.

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/PublicInbox/WatchMaildir.pm b/lib/PublicInbox/WatchMaildir.pm
index 2808b726..e28e602a 100644
--- a/lib/PublicInbox/WatchMaildir.pm
+++ b/lib/PublicInbox/WatchMaildir.pm
@@ -259,7 +259,9 @@ sub _importer_for {
                 if ($v == 2) {
                         eval { require PublicInbox::V2Writable };
                         die "v2 not supported: $@\n" if $@;
-                        PublicInbox::V2Writable->new($inbox);
+                        my $v2w = PublicInbox::V2Writable->new($inbox);
+                        $v2w->{parallel} = 0;
+                        $v2w;
                 } elsif ($v == 1) {
                         my $git = $inbox->git;
                         my $name = $inbox->{name};