EventTimeStatsAccum takes the following to be created:
As per design of Spark accumulators in Apache Spark, accumulator updates are automatically sent out (propagated) from tasks to the driver every heartbeat and then they are accumulated together.
add( v: Long): Unit
add is part of the
AccumulatorV2 (Spark Core) abstraction.
add is used when EventTimeWatermarkExec physical operator is executed.