Function when

fdbserver/DataDistributionTracker.actor.cpp:1032–1034

		loop choose {
			when(Promise<int64_t> req = waitNext(getAverageShardBytes)) {
				req.send(self.maxShardSize->get().get() / 2);
			}
			when(wait(loggingTrigger)) {
				TraceEvent("DDTrackerStats", self.distributorId)
				    .detail("Shards", self.shards.size())