proxy to apache timing out on php uploads?

[Nate Beaty]

hey folks,

for a fairly busy site that has the ability for users to upload 4
images at a time via php (which can be fairly large),  i am proxying
dynamic requests from nginx to apache2 with:

  location / {
    access_log  off;
    proxy_pass http://127.0.0.1:8080/;

    proxy_redirect off;

    proxy_set_header   Host             $host;
    proxy_set_header   X-Real-IP        $remote_addr;
    proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;

    client_max_body_size       10m;
    client_body_buffer_size    128k;

    proxy_connect_timeout      90;
    proxy_send_timeout         90;
    proxy_read_timeout         90;

    proxy_buffer_size          4k;
    proxy_buffers              4 32k;
    proxy_busy_buffers_size    64k;
    proxy_temp_file_write_size 64k;
  }

and i've been getting timeout errors (i believe that's what's
happening) every so often .. maybe 3-5 a day?

from mysql: Server error. 2006: MySQL server has gone away.

with these in PHP's $_SERVER global (not sure if this is helpful...)

   [REDIRECT_nokeepalive] => 1
   [REDIRECT_ssl-unclean-shutdown] => 1
   [REDIRECT_downgrade-1_0] => 1
   [REDIRECT_force-response-1_0] => 1
   [REDIRECT_STATUS] => 200
   [nokeepalive] => 1
   [ssl-unclean-shutdown] => 1
   [downgrade-1_0] => 1
   [force-response-1_0] => 1

is this in fact a timeout error from the proxy? i'd never seen these
errors until i set up the nginx to serve static files and relay php
requests to apache. (which, btw, was super easy and made me an instant
nginx believer!)

if it is indeed a timing out issue, which setting would i bump up to
accommodate large php uploads?

thanks in advance,
nate

ps: is there a daily digest option for this mailing list? it's quite busy...