I can see where my statement was ambiguous, I'd intended to say that the GC developers spend tons of time tuning their implementations to fit their users' workl

I can see where my statement was ambiguous, I'd intended to say that the GC developers spend tons of time tuning their implementations to fit their users' workloads. I will say that "government project which serves the whole country now" doesn't really specify how many requests you're doing or what kind of pauses are acceptable. If it's a traditional website, a 300ms GC pause might be invisible. A 2s pause might even be invisible. For a service doing 30,000 requests/s (~1-2k/s per machine), a single STW pause of 2s is _very_ disruptive. Even 300ms is high. A 300ms pause is 600 queued requests @ 2k/s. We certainly tune this service to eliminate most STW GC. We were even hit by http://www.evanjones.ca/jvm-mmap-pause.html http://www.evanjones.ca/jvm-mmap-pause.html .