[TYPO3-mvc] clearCacheCmd clears all pages all the time

[Stefan Wild]

Hey,

since my extension takes about 4–5 seconds to render many pages (since 
there are no SQL JOINs, I have to iterate in PHP through a few 
objects), I am depending on proper caching. Of course, proper caching 
includes clearing the cache when needed.

But, whenever I enable clearCacheCmd (set to specific pages) on the 
SysFolder I store the extension's objects in, all page cache gets 
cleared after a couple of requests. I am only using the TYPO3 backend 
for editing, the extension is just for the frontend and does not 
create, update or delete anything. But, even if there are no edits in 
the backend, all page cache (not only the PIDs I set clearCacheCmd to) 
gets cleared after a couple of requests. If I disable clearCacheCmd 
everything gets cached again and stays in the cache.

So, why might extbase clear the cache that often and why all page cache?

Best regards,
Stefan