It currently takes us a couple minutes to run the event dispatch loop, and on 3/7/19 we were pinned at processing 1000 events per loop iteration for several hours, which means that we were behind in processing events. We should
- Parallelize the loop. https://github.com/evergreen-ci/evergreen/blob/02c7b0e2d9305c8afab331b730693665b02731d6/units/event_metajob.go#L157
- Add logging for the number of tasks remaining. Currently the query gets 1000 tasks. We should have an additional query for the total number of tasks remaining so that if we get behind we can measure how behind we are.