Drupal 8 introduced an entirely new caching system, with actually good cache invalidation. Right now if I save new content on one of my sites, it queues an invalidation request that gets sent to Varnish (which can be run either as a shutdown function or via a queue runner on cron) and the new content shows up within seconds.

I’m not sure I read the OP the same way you did. If you read it as “can I build a site on the scale of Reddit or Twitter with Drupal” then no, don’t build Reddit or Twitter with Drupal. If you read it as “will Drupal serve a site with user generated content” then yes, it will, but if you’re planning to be a top 10 site on the internet, you’ll need a custom stack.

Gotcha. Thanks for the clarification!

> if you’re planning to be a top 10 site on the internet, you’ll need a custom stack.

And yeah, that's what I thought the OP was hinting at (or at least hoping to become).

It'll handle small-medium scale forums just fine. Probably any stack would.

There's a lot of room between small- to medium-sized and Reddit-sized. Drupal 9/10 scales out well and does just fine at that large (read "enterprise") size. But certainly the more read-heavy a site is, the more suited it is to Drupal.

I have never made that to work. With Akamai we are resorting to lower ttl for cache expiry. The tag based cache architecture in practice is not helping with constraints from CDN providers

Any chance of switching to Fastly? Or at least testing it? There's excellent documentation for a working setup here: https://docs.lagoon.sh/drupal/integrate-drupal-and-fastly/ I don't know how to get invalidation working on Akamai, but the process of getting it working on another provider might get you the insight you need to get Akamai working.

> if you’re planning to be a top 10 site on the internet, you’ll need a custom stack

To be fair, that's the case with pretty much any CMS. Even if they start with a stock system, by the time they actually hit top 100/1000 (let alone 10) there's a lot of custom work to be done.

And realistically, a "top 100/1000 site" is almost always going to have a cloud of other sub-sites and related properties. The corporate site, intranet/HR, jobs and recruiting, press center... The penumbra of "Oh, yeah, we need one of those... but it would be ridiculous to build it from scratch" sites for a large organization can be pretty large indeed.