Strange cookie behavior using HttpUserIdModule

[Matt Davies]

Hey all,

I'm seeing a strange behavior using the HttpUserIdModule.  I am seeing significantly more set operations that I would expect.  The ratio of about 50% sets to 50% gets remains constant regardless of the days covered. So, if I include 1 day then percentage is the same as if I include several days.  

The usage pattern of the clients and the sheer volume of users would indicate that we would not see 50% day after day.

So, on to specifics:

Configuration

userid          on;
        userid_name     uid;
        userid_domain   xyz.com;
        userid_path     /;
        userid_expires  365d;
        userid_p3p      'policyref="/w3c/p3p.xml", CP="CUR ADM OUR NOR STA NID"';

Requests flow in from 

Client -> DNS load balance -> HA load balance -> 1 of 6 nginx servers

HA load balance is HAProxy.

There are 6 identically configured servers that accept requests.  We are sending the cookie as a 3rd party cookie - i.e. the cookie comes because of a javascript on zxc.com which requests something from xyz.com (our site).

I am trying to figure out if this is a user agent not respecting the cookie or something else. 

Has anyone seen strange results utilizing this setup?

Thanks!