How come I am not getting bugs about these emails ! Bugzilla bug :-)

Anyway, we already do this (from the indexhelper log):
20080322 15:32:25.5117 25247 IndexH DEBUG: Set best effort IO priority to    lowest level (7)
20080322 15:32:25.5180 25247 IndexH DEBUG: Process was already niced to 19,  not renicing to 12

Its not done via the script but directly in code. Unfortunately ionice can only go so far :-). Also note that, beagle tries to leave the buffer cache as much undisturbed as possible by asking the kernel to remove the file from buffer cache when its done. Actually I think this is where it causes the problem, because files already in the buffer cache are also removed; fixing that would be very complicated, since it is not easy to figure out if a file is in the buffer cache. Instead beagled takes a middle ground conservative approach, it only modifies the buffer cache during crawling but not when a file is modified or created; it assumes that a file recently created or modified would be used in the future. These are all heuristics and they work well in practice but there are always corner cases that will blow up.