At least three organizations were unable to list the groups in the groups' section (UTC-05 23-09-15 13:02 to 23-09-18 12:37: 3 days -time to recover-). The incident was detected reactively (at UTC-5 23-09-18 10:23: 2.9 days -time to detect-) by a user, who reported through our help desk [1] that when entering the list of his organizations they did not load.
The problem was generated by a merge request [2] that was made with the objective of displaying real-time indicators, which works by making individual requests to the database, which degraded the performance and generated 504: Timeout error errors.
The merge request that caused the problem was reverted [3] and the groups were subsequently verified to load correctly.
As it was a performance issue it could not be tested before it occurred in production with all the data that goes with it. IMPOSSIBLE_TO_TEST