Problem/Motivation
I have a large site, with a lot of active content creators, but the vast majority of the site is still unauthenticated traffic. The site is on Pantheon, and we use Cloudflare as well, with the purge integration (yes, I know Pantheon provides their own CDN, it's just the way it is). I've observed a few issues with this setup.
- We seem to perpetually be at the rate 1200/requests per 5 minute rate limit.
- Our cache hit rate seems very low.
This seems to cause the site to have some pretty terrible performance, in part, due to the amount of traffic hitting un-cached pages. After doing some digging, I've found that our purge queue seems to generate a lot of items whenever a piece of content is edited. Editing one page, generated ~70 cache tags added to the queue. Including a lot of redundant items. Now I am looking at incorporating this
Purge Queues →
module. But this still seems to add a lot of tag invalidations for paragraphs specifically. For example, after one page edit, it queues up the following tags:
- paragraph_list
- paragraph_list:{paragraph type} - for every paragraph type used.
- paragraph:{paragraph id} - for every paragraph entity.
Now, it's my assumption that the main intention of purge is to communicate with external services like CDN's, to remove any cached pages. Tag based invalidation is handy for this as we don't need to pass the specific page URL, but two things strike me here.
The page is already being purged via the "node:{node id}" unless you use a module like "Paragraphs Library", which is an unusual setup, you won't have paragraphs appearing on pages without their host nodes. For the paragraph_list:{paragraph type}, it's the same. That also seems extra problematic, as purging the paragraph type tag seems like it would purge large swaths of the site unnecessarily.
Now, as I'm typing this, I discovered I can configure the Core Tags Queuer "blacklist" (might want to review that language...) and I am trying adding the tags I mentioned to that. I'll report here if it makes any improvement to our performance/hit rate. If so, then maybe this issue will help point future developers in the right direction to that feature.