Thanks for taking the time to report this!

Which versions of MediaWiki and which version of AbuseFilter is this about?
Also see http://www.mediawiki.org/wiki/Manual:How_to_debug

kazink wrote:

Which versions of MediaWiki and which version of AbuseFilter is this about?

Sorry, forgot to add this: MW 1.21, AbuseFilter master.

I will try to debug when I have some time.

kazink wrote:

I found out that the internal count of filter hits read from Memcached is always 0. I don't have Memcached enabled.

isThrottled function (AbuseFilter.class.php)
$key = 'wiki:abusefilter:throttle:2:user:3' (seems legit)
$count = 0 (always).

I think the problem is that AbuseFilter always uses Memcached for throttle, even if it's not enabled.

Change 92266 had a related patch set uploaded by Kaldari:
Only allow throttling if object caching is enabled...

https://gerrit.wikimedia.org/r/92266

• Bug 55816 has been marked as a duplicate of this bug. ***

Change 92266 merged by jenkins-bot:
Only allow throttling if object caching is enabled...

https://gerrit.wikimedia.org/r/92266

Probably "throttle" should be taken out of the user interface if there is no memcached enabled?

Also "blockautopromote" is using memcached only and I believe this is actually bug 20487

The "fix" for this appears to be a band-aid. The throttle should be made to work without object caching, rather than simply being hidden when it is not present.

(In reply to comment #8)

The "fix" for this appears to be a band-aid. The throttle should be made to
work without object caching, rather than simply being hidden when it is not
present.

Probably some code using $wgMemc can just use wfGetCache( CACHE_ANYTHING );