What does the Spark UI light blue part of Tasks progress bar indicate?

Question

Below is a screenshot of the Apache Spark UI showing the progress of Stage 0. Under the Tasks column there is a dark blue and a light blue part of the progress bar. The dark blue part corresponds to the number of tasks that have succeeded [1075/3200 in the screenshot below].

What does the light blue part of the progress bar indicate? Thanks!

Answer 1

• total size of the bar represents a number of tasks for a given stage
• dark blue part of the part represents tasks which have already finished
• light blue part of the bar represents currently running tasks