Full page cache not working, appears to be caching per session instead of per user group

Question

Full page caching appears to be working on a per session basis.

• If I go to a page, the first page load takes a few seconds, the second page load much less
• If my co-worker visits that same page, it takes a few seconds and the second page load much less.

We have exhausted all the FPC documentation, tutorials, and posts we can find. We are completely out of ideas, We have hole punched the one per session object on our pages (cart contents) and FPC still appears to only work on a per session basis instead of on a user group basis like we would expeect.

Any idea why this would be occurring?

Answer 1

What you are describing isn't default behaviour.

Typically as FPC is primed, when not logged in - or having done anything to make the session specific to you, the page load timeline tends to be:

--1.2s--------0.8s------------------0.6s-----------------------0.1s---------------
  Uncached    Mage default cache    Partially cached in FPC    Fully cached in FPC

What should happen is that a single page load primes the Magento cache and to a lesser degree, the Magento FPC cache. The subsequent load for the same content fully primes the FPC cache resulting in a 3rd page load for the same content to take around 0.1s.

But when you do something to make your session unique, eg, add-to-cart - then FPC exhibits slightly different behaviour and the render times do increase slightly.

--1.4s--------0.8s------------------0.6s---------------
  Uncached    Mage default cache    Fully cached in FPC

It sounds like you've broken the FPC logic by make your amendments (hole-punches) by essentially causing FPC to behave like in my second example.

Ie. It doesn't serve any content from a global cache, but rather only content specific to your session

My suggestion would be to either install a clean EE store - and watch the behaviour there - or move the local/community directories and custom theme package directories (to force enterprise/default to load).