What does the "event timer add" step in the debug log signify?

[nginx user]

i am having a problem with trying to use oauth services in that the
callback from the provider gets “stuck” on my server. The logs in the
pastebin here: http://pastebin.com/qncJKVwQ summarise the experience.


Nginx is setup as reverse proxy to Apache which handles PHP using CGI. that
is, the old fashioned CGI and not fastCGI.


So the stream of things see to be as follows:


1. User makes login request to a PHP file
2. Nginx proxies this to Apache
3. Apache runs PHP and redirects to oauth provider
4. Provider authenticates and returns callback
5. Nginx proxies this to Apache
6. Apache runs PHP, user is logged in and redirected to index.php
7. Nginx proxies this to Apache
6. Apache runs PHP and serves index.php


On rare successful attempts, there is a big delay in Step 5 and most of the
time I just get a 504 Timeout response.

Steps 2, 5 & 7 are essentially the same thing but the issues only arises
with Step 5 with the callback request.


A look at the debug log shows the issue comes in on the callback call
between the "event timer add" & "post event” steps.


Will appreciate any insights.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.nginx.org/pipermail/nginx/attachments/20170208/929d93d3/attachment.html>