The heap dumps from these machines are quite small (<= 9.0G), which is usually an indicator that the retained numbers won't make sense. However, from the dump on 2007 it would appear that the conditions mirror that of what was found in T153588: Cassandra OOMs on restbase1009-a, restbase1011-c and restbase1013-c (that reads generated by the retention policy are materializing a large number of tombstoned values onto the heap).

The page in question here is: https://commons.wikimedia.org/wiki/Commons:Open_Access_File_of_the_Day/recent_uploads/2016_October_27-31.

I am way past due to return the resources allocated to the VM I used in this analysis (T153711: Revert increased quota for services-test labs project), and am planning to decommission it by COB today. I will however leave these heaps in place for a few more days, just in case any questions arise that would require more exploration to answer (we could get another VM if we had to).