Setting num-messages to 100 and adding explanation

bin/manifold_cbc_bank_snr_optimizer_online

@@ -123,8 +123,12 @@ class SNROptimizer(object):
 		self.last_event_time = 0
 
 		# init options for kafka
-		# FIXME: is default num_messages = 10 ok?
-		self.num_messages = 10
+		# With a theoretical maximum of 1 s-event per second, 5 g-events
+		# per s-event, an optimizer latency of 240s, and 10 optimizer jobs
+		# running in parallel, we get a maximum
+		# possible message build-up of 240*5/10 ~ 100 messages
+		# NOTE: change this if 10 optimizer jobs in parallel is changed
+		self.num_messages = 100
 
 		self.kafka_settings = {
 			"bootstrap.servers": kafka_server,