Today, starting at 2017-01-24 18:44 UTC, the visual-diff testreduce on ruthenium.eqiad.wmnet started spawning processes, ending with the almost complete hang of the host due to full RAM and swap.
I had to stop both parsoid-vd-client and parsoid-vd processes and disable Puppet to avoid it to restart them. Because if they are restarted the test starts again spawning processes and ending up hanging the host.