If it helps any, I do not see this in Windows 10. After 5,000 iterations the "low memory" mark, as reported by windows, is still just 1,101MB.
On Monday, August 24, 2020 at 5:05:00 AM UTC-4 vlad...@varank.in wrote: > Hey, > > I haven't looked deep but I recall there had been a note about runtime > change in Go 1.13's https://golang.org/doc/go1.13#runtime That is > > > The runtime is now more aggressive at returning memory to the operating > system to make it available to co-tenant applications [..] However, on many > OSes, including Linux, the OS itself reclaims memory lazily, so process RSS > will not decrease until the system is under memory pressure. > > Could that be the behaviour you observe (although, since you don't see the > same in C implementation, I might be confused, sorry in advance). > > On Sunday, August 23, 2020 at 5:05:22 PM UTC+2 Manish Rai Jain wrote: > >> Hey Gophers, >> >> I'm puzzled by a mysterious RSS memory spike in my Go program, when all >> memory allocations are happening via Cgo. I assert that there are no memory >> leaks in the program. And have written another C program with similar logic >> which does NOT show RSS memory spiking. So, I suspect this is something to >> do with Go memory. >> >> <https://github.com/dgraph-io/ristretto/pull/186> >> Program: >> >> https://github.com/dgraph-io/ristretto/pull/186 >> >> This PR creates a Go memtest program, which does this: >> - Uses z.Calloc and z.Free to allocate Go struct (S) and a byte slice >> inside it. All allocations are happening in Cgo, and being type casted into >> Go. No allocations are happening in Go (except a 32 MB fill slice). >> - z.NumAllocBytes is tracking memory allocated and freed by these calls. >> - Increases memory usage to 16 GB (as reported by z.NumAllocBytes). >> - Decreases it back to 1 GB. >> - Repeats this cycle. >> - On Ctrl+C, it deallocates everything and asserts that Cgo memory >> allocated is zero. >> >> I was concerned about memory fragmentation, so created a very similar C >> program which does the same thing (memtestc). >> >> Please feel free to run either of the Go or C programs. They should >> compile and run easily. >> >> Behavior: >> >> Run the program with: `go build . && ./memtest` . Go pprof heap shows 32 >> MB used, to account for the fill slice. However, RSS reported keeps roughly >> increasing every cycle. >> >> I'm using Go 1.14.4 and on it, RSS jumps to 22GB after a few cycles. >> memtestc >> (C equivalent, compiled with gcc) does not show this behavior. The RSS goes >> down to 1GB-ish every cycle. >> >> Any clues why the RSS is much higher than expected in Go and keeps >> climbing in Go? >> >> — >> Manish >> Founder, https://dgraph.io >> > -- 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. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/10a3bfa0-5672-4471-b7f1-5c2836baa55an%40googlegroups.com.
