Issue

The expired messages can be removed from the broker in two different ways:
1) Using the periodical check
2) When a consumer attempts to receive them

When the messages are removed by the periodical check, they seem to be first acquired before being discarded:

acquires               100000
discardsTtl            100000

But when they are removed while a consumer tries to consume them, the "acquires" statics doesn't change:

acquires               0
discardsTtl            100000

Is there some reason why the messages are acquired only by the periodical check? Is that a bug?