First, thanks for the suggestions.
1) the part for this site shutdown that seems to be the issue is:
2016-12-03T21:32:58 INFO ZServer HTTP server started at Sat Dec 3 21:32:58 2016
2016-12-03T21:33:02 INFO Plone OpenID system packages not installed, OpenID support not available
2016-12-03T21:33:04 INFO Zope Ready to handle requests
2016-12-03T21:33:05 INFO plone.app.theming.policy local cache invalidated on thread 140416490993408
2016-12-03T21:33:05 INFO plone.app.theming.policy initializing local cache on thread 140416490993408 for https://www.docentims.com::barceloneta
2016-12-03T21:33:05 INFO plone.app.theming.policy local cache invalidated on thread 140416482600704
2016-12-03T21:33:05 INFO plone.app.theming.policy initializing local cache on thread 140416482600704 for https://www.docentims.com::barceloneta
2016-12-03T21:33:21 INFO SignalHandler Caught signal SIGTERM
2016-12-03T21:33:21 INFO Z2 Shutting down fast
2016-12-03T21:33:21 INFO ZServer closing HTTP to new connections
2016-12-09T21:50:15 INFO ZServer HTTP server started at Fri Dec 9 21:50:15 2016
after I restart, it quits for the same reason and references the Barcelona theme.
2) another one of my sites shutdown and appears to be a mosaic issue. I reported one bug, I report this and see if he agrees it is a bug. I removed all the tiles from this test site and uninstalled mosaic. see what happens.
3) the third site has the same issues as (1) above.
I've never seen this and have no idea what is going on.
I've seen the suggestions about what I am hosting it on; however, that hasn't changed and prior to these shutdowns (been happening for months, just never saw a common cause). Also, it isn't a memory issue.
Any suggestions? I can make the full instance logs available for all three sites.
I wait and see what happens with the one site were the issue seems to be mosaic related and see if I still get the same error messages.