Comment 0 for bug 1282089

This is remarkable noticeable from Horizon which use keystoneclient to connect to the keystone server and at each request this later is left hanged there which consume the keystone server and at one point this will result to having keystone server process exceeding the limit of connection that is allowed to handle (ulimit of open filed).

## How to check:

If you have horizon installed so just keep using it normally (creating instances ....) while keeping an eye on the server number of opened files "lsof -p <keystone-pid>" you can see that the number increment pretty quickly.

## Why:

This because keystone client doesn't reuse the http connection pool, so in a long running service (e.g. horizon) the effect will be a new connections created for each request no connection reuse.

Patch coming soon with more details.