What are ThreadPoolExecutors jobs in web UI's Spark Jobs?

Question

I\'m using Spark SQL 1.6.1 and am performing a few joins.

Looking at the spark UI I see that there are some jobs with description \"run at ThreadPoolExecutor.java:11

Answer 1

This also happens when reading and writing to csv.

During those operations is when I first witnessed this threadpoolexecutor for the first time.