Cache purge limitations - exact value of the limit

[Robert Dadic]

Greetings everyone! 

I have begun implementing an automated functionality for purging url paths in Pagespeed from our platform and everything is pretty much as clear as day, but there is one minor thing that I'm curious about and would really like to get more information on it.

Regarding this: https://www.modpagespeed.com/doc/system#purge_cache, more specifically this part:

There is a limitation to the number of distinct URLs that can be purged. When that limit is exceeded, everything in the cache older than the oldest remaining purge request will be dropped. The limitation is high enough that it's not expected to be exceeded often, but is not currently changeable.

I unfortunately couldn't find what that number is exactly, and it would really be useful considering that at times, within the automated mechanism I'm currently implementing, a somewhat big amount of specific url paths will have to be purged in batches because I want to avoid purging everything (CSS and JS specifically).

I can easily wrap up the functionality and leave the batch size to be configurable, but in the case I configure a 'wrong' batch size and I exceed the limitation, I would like this bit clarified as well if possible:

When that limit is exceeded, everything in the cache older than the oldest remaining purge request will be dropped.