"1/61 of the time, check the global run queue." Stuff like this is a little odd; I would have thought this would be a variable dependent on the number of physical cores.
I once profiled a slow go program running on a node with 168 cores, but cpu.max was 2 cores for the cgroup. The runtime defaults to set GOMAXPROCS to the number of visible cores which was 168 in this case. Over half the runtime was the scheduler bouncing goroutines between 168 processes despite cpu.max being 2 CPU.
The JRE is smart enough to figure out if it is running in a resource limited cgroup and make sane decisions based upon that, but golang has no such thing.
https://github.com/golang/go/blob/a1a151496503cafa5e4c672e0e...
As said in 2019, import https://github.com/uber-go/automaxprocs to get the functionality ASAP.
Always a weird feeling, it’s a small world
If they'd now also make the GC respect memory cgroup limits (i.e. automatic GOMEMLIMIT), we'd probably be freeing up a couple petabytes of memory across the globe.
Java has been doing these things for a while, even OpenJDK 8 has had those patches since probably before covid.
> It may overcount the amount of parallelism available when limited by a process-wide affinity mask or cgroup quotas and sched_getaffinity() or cgroup fs can’t be queried, e.g. due to sandboxing.
[1] https://docs.rs/tokio/1.45.0/src/tokio/loom/std/mod.rs.html#...
[2] https://doc.rust-lang.org/stable/std/thread/fn.available_par...
90s_dev•9h ago
NAHWheatCracker•8h ago
I'm not a low level optimization guy, but I've had occasions where I wanted control over which threads my goroutines are running on or prioritizing important goroutines. It's a trade off for making things less complex, which is standard for Go.
I suppose there's always hope that the Go developers can change things.
silisili•7h ago
If you model it in a way where you have one goroutine per os thread that receives and does work, it gets you close. But in many cases that means rearching the entire code base, as it's not a style I typically reach for.
naikrovek•2h ago
silisili•2h ago
That said, if you're greenfielding and see this as a limitation to begin with, picking another language is probably the right way.