I noted the discussion also about "authentication" with WCQS Beta 2 coming Feb. 2.
Reading through some of the talk over the past few months (and catching up from holidays)...
https://commons.wikimedia.org/wiki/Commons_talk:SPARQL_query_service/Upcoming_General_Availability_releaseOnce a problematic query is executed, it can lock up Blazegraph and
cause it to become unresponsive – because we are unable to kill the
query, we are forced to restart Blazegraph manually each time, causing
user-wide disruptions, and taking a lot of emergency time and energy for
the WMF team to resolve (at the expense of other improvements,
features, projects).