Re: [PATCH 0/2] leak workarounds for Perl 5.16 on CentOS/RHEL 7

[Konstantin Ryabitsev <konstantin@linuxfoundation.org>]

On Thu, Sep 26, 2019 at 01:50:36AM +0000, Eric Wong wrote:
>After many hours of reviewing our code in PublicInbox::Qspawn,
>PublicInbox::GitHTTPBackend, and PublicInbox::HTTP and finding
>nothing but cleanups and documentation improvements; it seems
>the leaks affecting lore is down to bugs in Perl 5.16.3.
>
>After removing the warning for Deflater being missing in
>d883d4a93b23be134038e28f421eafca70c3d838
>("httpd: get rid of Deflater warning"), I missed that my
>own CentOS 7 VM was missing that module so was unable to
>reproduce the FD leaks :x
>
>The first patch is a straightforward workaround that I was
>able to test without Plack::Middleware::Deflater being installed.
>
>The second patch stops loading Deflater in httpd on Perls
>earlier than 5.18.  (But I haven't built or tested 5.18 myself).
>Enabling gzip in varnish will be needed for 5.16 users.

Yay, I can confirm that the latest master fixes all the FD leaks that 
have been plaguing lore.kernel.org for the past few weeks. The number of 
pipes is stable and there are no (deleted) tempfiles showing up. Thanks 
so much for this!

Can you elaborate on gzip+varnish changes? I'm assuming it's something 
as simple as:

@@ -63,6 +63,10 @@
        } else {
                /* short TTL for up-to-dateness, our PSGI is not that slow */
                set beresp.ttl = 10s;
+               /* Compress text responses on CentOS7 */
+               if (beresp.http.content-type ~ "text") {
+                       set beresp.do_gzip = true;
+               }
        }
        return (deliver);
 }

-K