History files for large jobs can be hundreds of GB. These history files take too much space and create a backlog on the history server.
Most of the size is from Accumulables in SparkListenerTaskEnd. The largest accumulable is internal.metrics.updatedBlockStatuses, which has a small update (the blocks that were changed) but a huge value (all known blocks). Nothing currently uses the accumulator value or update, so it is safe to remove it. Information for any block updated during a task is also recorded under Task Metrics / Updated Blocks.