Canvas announced there was intermittent slowness in the system from 9:30AM until 2:30PM EST that may have effected some users. Below is their original message.
Canvas Incident Report
Some users saw job related slowness today between 7:30 MDT and 12:30 MDT
Some users saw long wait times on jobs within Canvas, today April 18 between 7:30 am MDT and 12:30 pm MDT. This was due to a new regrade process for multiple grading periods, this process has to recalculate every grade in a course, but is not resource demanding. Because of this lack of demand our automated process to ramp up more resources was not triggered. These regrades take a large amount of time, and create a backlog. Our DevOps team has monitoring setup to manually add resources now, and they are investigating better ways to run these processes in the future.
We are sincerely sorry for the recent delays on jobs lately. We understand how important these jobs are, especially gradebook exports.