This was raised by MTG in their testing that dumping the CRL Cache through Kleopatra does not work.

And indeed, what Kleopatra does is to send:

"dirmngr --flush" to clear the CRL Cache.
"gpgsm --call-dirmngr listcrls" to show the CRL Cache.

I can see that flush removes the files in the CRL cache but "gpgsm --call-dirmngr listcrls" lists the same CRL's before and after the flush. Killing dirmngr resolves this.

So I think dirmngr needs to also flush any in memory cache when flushing. I guess the problem is that the flush is called on a new dirmngr instance. Any advice about how Kleo should call the flush?

To reproduce:

import  http://files.intevation.de/users/aheinecke/aheinecke-2018.pem
gpgsm --with-validation -k aheinecke@intevation.de   
gpgsm --call-dirmngr listcrls
dirmngr --flush
gpgsm --call-dirmngr listcrls

I think this is low priority because that is mostly a development / testing feature and I don't think that we have any regression here.