Okay, I admit it: "my initial strategy for 'memcached sessions' didn't survive the load balancer ..."
 

... Even in bare-initial testing, it became obvious that the various load-balanced computers were "trashing" one-another's version of "the current session state." :rolleyes:

Okay, sure, sure ... I can Google DuckDuckGo™ a great-plenty web pages such as this one, but ... let's face it ... "that particular web-page was written seven years ago, and I don't have time to waste."

So ... what's the currently-best strategy now??

(Yes, "the application in question" is PHP. ("PHP god-knows how-old.") Being dragged, fairly kicking-and-screaming, into the present status-quo.) :rolleyes:

(Hyperlinks welcome requested.)

Caching Hat-trick: Varnish, Memcached and PHP libraries - July 13, 2015 may offer some insight?