From 2019-04-19T00:56:35 until 2019-04-22T03:59:33 (that is 3 full days) there was database contention while running MovePage::move on the query:
UPDATE `categorylinks` SET cl_sortkey = 'KITCHENER PARK (PARKE SA NUZELAND)',cl_collation = 'uppercase',cl_type = 'page',cl_timestamp=cl_timestamp WHERE cl_from = '6304172' AND cl_to = 'Articles,_Parke'
with variations on sortkey and cl_from, causing >11K:
Deadlock found when trying to get lock; try restarting transaction
This may be unavoidable given the many? api calls executed, but it caused database contention, so maybe it can be avoided/shows a place for potential optimizations (e.g. assume that if a page is edited, similar updates to pagelinks will happen so maybe they can be batched?), even if it is on the tooling used or the suppositions about the number of links/templates of a page.
Low priority because it is no longer happening, but it may be interesting to analyze and see if there is room for improvement.