Github user revans2 commented on the issue:
https://github.com/apache/storm/pull/2829
The reason we want to send a single tuple is because of how we do flow
control in the spouts. If you want to send more it can be more efficient, but
you risk going over the max.spout.pending amount that is set by the user, and
in 2.x where an emit can block, you risk having the spout block as well.---
