[druid-user] why I can't use tranquility to send data to druid?

I would check the code for your Tranquility version and see what’s happening on line 187 of ClusteredBeam:

Caused by: java.lang.NullPointerException
at com.metamx.tranquility.beam.ClusteredBeam$$anonfun$10.apply(ClusteredBeam.scala:187)

If you’re on 0.8.2, maybe something with the tuning object or the segmentGranularity:

val bucket = tuning.segmentBucket(timestamp)