Upload module + PHP causes active connections to continually increase

[Valery Kholodkov]

Support wrote:
> Hi all,
> 
> I'm developing a site using the upload module v2.0.11 ( from
> http://www.grid.net.ru/nginx/upload.en.html ) and just turned on the
> Stub Status module. I noticed that each time I send an upload form,
> the "active connections" number in the stats increments by one.
> 
> For example, if I start up Nginx and visit the status, I get:
> 
> Active connections: 1
> server accepts handled requests
>  1 1 1
> Reading: 0 Writing: 1 Waiting: 0
> 
> After opening the upload form in a new tab, uploading a file, and
> getting a response from the PHP script, I get:
> 
> Active connections: 2
> server accepts handled requests
>  3 3 3
> Reading: 0 Writing: 2 Waiting: 0
> 
> After uploading another file, I get:
> 
> Active connections: 3
> server accepts handled requests
>  4 4 5
> Reading: 0 Writing: 3 Waiting: 0
> 
> I'm concerned that the "active connections" number keeps increasing
> (as well as the "writing" number), and never seems to go down. Does
> this mean that Nginx is holding extra connections (and possibly extra
> file descriptors) open? I'm wondering if this will be a problem once I
> deploy the site and the server is running for long periods of time.
> Could it reach some system maximum of open file descriptors?
> 
> I thought it might be a problem with my fastcgi setup, but the active
> connections number doesn't increase when I visit regular (non-upload)
> PHP pages. Also, the problem didn't occur when I set @accept (in
> config below) to redirect to a .txt file instead of a .php file. In
> that case, the file appears in the upload directory, but I get a 405
> error because Nginx rejects POSTs to static files.
> 
> The relevant section of my nginx.conf is:
> 
> location /accept {
> 	upload_pass   @accept;
> 	upload_store  /var/www/fbp/uploads/files;
> 	upload_set_form_field  "$upload_field_name[name]" "$upload_file_name";
> 	upload_set_form_field  "$upload_field_name[content_type]"
> "$upload_content_type";
> 	upload_set_form_field  "$upload_field_name[tmp_file]" "$upload_tmp_path";
> 	upload_aggregate_form_field  "$upload_field_name[size]" "$upload_file_size";
> 	upload_pass_form_field  "key";
> }
> 	
> location @accept {
> 	rewrite ^(.*)$ /accept.php last;
> }
> 
> location ~ \.php$ {	
> 	fastcgi_pass   127.0.0.1:9000;
> 	fastcgi_index  index.php;
> 	fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
> 	include       fastcgi_params;
> }
> 
> My accept.php is simply:
> 
> <?php
>  die('accept.php'); ?>
> 
> After the upload, the files appear in the uploads/files directory, and
> the text 'accept.php' is properly returned to the browser.
> 
> Does anyone know what could cause this, and whether I should be
> concerned? Any help would be appreciated!

Using this patch or switching off keepalive might solve the problem.

-- 
Best regards,
Valery Kholodkov
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