Re: [PATCH v5] send-email: --batch-size to work around some SMTP server limit

From

Ævar Arnfjörð Bjarmason <avarab@gmail.com>

Date

May 22, 2017, 09:26 UTC

Message-ID

<CACBZZX5GYV50rjg9X602JHqFPaoofH9TwDf_-r_MDu8-rmNV6Q@mail.gmail.com>

In-Reply-To

<20170521125950.5524-1-zxq_yx_007@163.com>

On Sun, May 21, 2017 at 2:59 PM, xiaoqiang zhao <zxq_yx_007@163.com> wrote:

> Some email servers (e.g. smtp.163.com) limit the number emails to be
> sent per session(connection) and this will lead to a faliure when
> sending many messages.

This OK to me, the nits I had are addressed by Junio's reply.

diff --git a/git-send-email.perl b/git-send-email.perl
index 8a1ee0f0d4..c2d85236d1 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -1363,6 +1363,10 @@ EOF
                        die __("The required SMTP server is not
properly defined.")
                }

+               my $num_tries = 0;
+               my $max_tries = 5;
+       smtp_again:
+               eval {
                        if ($smtp_encryption eq 'ssl') {
                                $smtp_server_port ||= 465; # ssmtp
                                require Net::SMTP::SSL;
@@ -1429,6 +1433,22 @@ EOF
                        }
                        $smtp->dataend() or die $smtp->message;
                        $smtp->code =~ /250|200/ or die
sprintf(__("Failed to send %s\n"), $subject).$smtp->message;
+                       1;
+               } or do {
+                       my $error = $@ || "Zombie Error";
+
+                       warn sprintf(__("Failed to send %s due to
error: %s"), $subject, $error);
+                       if ($num_tries++ < $max_tries) {
+                               $smtp->quit if defined $smtp;
+                               $smtp = undef;
+                               $auth = undef;
+                               my $sleep = $num_tries * 3; # 3, 6, 9, ...
+                               warn sprintf(__("This is retry %d/%d.
Sleeping %d before trying again"),
+                                            $num_tries, $max_tries, $sleep);
+                               sleep($sleep);
+                               goto smtp_again;
+                       }
+               };
        }
        if ($quiet) {
                printf($dry_run ? __("Dry-Sent %s\n") : __("Sent
%s\n"), $subject);

Now that's very much a WIP and I don't have a server like that to test against.

Having worked with SMTP a lot in a past life/job, I'd say it's *very*
likely that you're just getting a /^4/ error code from 163.com,
probably 421, which would make this logic even simpler. I.e. we could
just adjust this to back-off for /^4/ instead of trying to handle
arbitrary errors.

Anyway, I'm not interested in pursuing that WIP patch, and I don't
think perfect should be the enemy of the good here. Your patch works
for you, doesn't really damage anything else, so if you're not
interested in hacking up something like the above I think we should
just take it.

But I do think it would be very good to get a reply to you / details
in the commit message about what error you get exactly in this
scenario, see if you get better details with --smtp-debug, and if so
paste that (sans any secret info like user/password you don't want to
share).

Then if we're poking at this code in the future we can maybe just fix
this in some more general fashion while keeping this use-case in mind.