Question: I have a website hosted under a subdomain for testing purposes and have tried to validate the html and css using w3 validator and jigsaw. Depending on the URL I use - <http://alt.example.com> (9 frameset type errors 4.01 Strict, CSS3 pass) OR <http://www.example.com/alt> (passes HTML5 / fails CSS3 183 errors, mostly vendor extensions). Why do the links validate differently and which one should I be concerned with? Any ideas on how to go about fixing them would be great. 

Mystique Theme,
Mystique-Child Theme (with its own style.css using @import url for core.css),
WordPress 3.4

Answer: 
The answer depends on how many such requests will happen and how many concurrently in your web app ? Connection pooling is usually a better idea if you expect your web app to be busy with 100s or even 1000s of user concurrently logged in. If you are only doing this as a side project and expect less than few hundred users, you can probably get away without pooling.
Pooling seems to be totally impossible in context of Flask, FastAPI and everything relying on wsgi/asgi dedicated servers with multiple workers.
Reason for this behaviour is simple: you have no control about the pooling and master thread/process.
A pooling instance is only usable for a single thread serving a set of clients - so for just one worker. Any other worker will get it's own pool and therefore there cannot be any sharing of established connections.

Logically it's also impossible, because you cannot share these object states across threads/processes in multi core env with python (2.x - 3.8).