What OS distro and kernel version are you running? I also because any time someone mentions "interesting" behavior with futex_wait, my knee-jerk reaction is to first rule out the issue described in this previous posting <https://groups.google.com/d/msg/mechanical-sympathy/QbmpZxp6C64/BonaHiVbEmsJ> before spending too much time investigating other things. Ruling it out is quick and easy (make sure your kernel is not in the version ranges affected by the bug described), so well worth doing as a first step.
Assuming you issue is NOT the one linked to above. You have some analysis and digging to do. I'd say that when having 200 actually active JVMs run on 80 cpus, seeing significant time spent in futex_wait is not necessarily a surprising situation. It [heavily] depends on what what the applications are actually doing, and what their activity patterns look like. You'd need to study that and start drilling down for explanations from there. Speculating about the cause (and potential solutions) based on the info below would be premature. On Sunday, January 22, 2017 at 8:42:54 PM UTC-8, Дмитрий Пеньков wrote: > > Hello everyone. I have following situation: multiple HotSpot JVMs with > multiple GCs' (ParallelGC) threads on multiple CPUs. I've already seen > recommendations to have min 2 cores per JVM, but in my case it's 80 CPU's > and about 200 JVMs. After working for about an hour, I have >95% of time > for futex syscall futex_wait. I tried to fix the number of parallel GC > threads in 4, but it didn't make effect. Mb GC changing can help? How to > solve this situation? > -- You received this message because you are subscribed to the Google Groups "mechanical-sympathy" group. To unsubscribe from this group and stop receiving emails from it, send an email to mechanical-sympathy+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
