Currently czar caches empty chunk list after it reads the list from file. This complicates things when we need to update the list, integration test for example has to restart czar process after it loads new data to make sure that czar updates its cached list. Would be nice to have simpler mechanism to resetting cached list in czar without restarting it completely. It could be done via special query (abusing FLUSH for example) or via sending signal (problematic if czar runs remotely).
This can be potentially useful even after we replace empty chunk list file with some other mechanism as I expect that cache will stay around even for that.