On Sun, Jul 31, 2016 at 9:13 AM, Jan Mercl <0xj...@gmail.com> wrote: > > On Sun, Jul 31, 2016 at 5:44 PM Brad Fitzpatrick <bradf...@golang.org> > wrote: > > > You should expect at most 10ms pauses for large heaps as of Go 1.6, and > especially in Go 1.7. > > I'm assuming those 10ms are valid for most/typical programs and that the > worst case of some, still perfectly reasonable programs[0], cannot be > guaranteed to be on average that low[1]. Is that assumption correct? >
The design specifies a 10ms worst case STW pause for all types of load. If needed, your program's allocations (producing your example of a 32GB singly-linked list) will start participating in small pieces of the concurrent garbage collection themselves, thus slowing down the rate of allocation and speeding up the collection. If you have a program that exhibits over 10ms pauses, Rick & Austin would be interested in debugging it. They have such worst-case programs themselves which they run regularly but still enjoy bug reports. Include the output of GODEBUG=gctrace=1 in your bug report. Go 1.5 had the 10ms goal but had known deficiencies late in the cycle which prevented it from hitting the goal in some extreme cases. Go 1.6 fixed those, but some other rare cases were found which prevented hitting the 10ms goal in other extreme cases. Go 1.7 fixed most of those and started working more on throughput, using less CPU to achieve the same goal. An additional optimization atop the existing design is potentially landing in Go 1.8. The GC people can correct me if I got this wrong. > [0]: Let's imagine for example a program repeatedly producing a tiny > sized node single linked list of size, say 32GB, doing something with it > and throwing it away afterwards for the GC to deal with it. > [1]: Or the pause must move instead to malloc waiting for the GC to free > memory, so technically it's not [directly] a GC pause. > > -- > > -j > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
