BTW, how are you measuring RSS? That is a trick all by itself! See https://groups.google.com/g/golang-nuts/c/LsOYrYc_Occ/m/LbjLAsL6BwAJ
Regards, Mike golang-nuts@googlegroups.com wrote on 08/23/2020 11:04:47 AM: > From: Manish R Jain <manishrj...@gmail.com> > To: "golang-nuts" <golang-nuts@googlegroups.com> > Date: 08/23/2020 11:04 AM > Subject: [EXTERNAL] [go-nuts] Mysterious RSS memory spike > Sent by: golang-nuts@googlegroups.com > > 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. > > 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 > [image removed] > -- > 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/a592db0482f1843c694a9486379a47dd%40frontapp.com. -- 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/OFD256528A.E55B2BFE-ON852585CD.00651CB3-852585CD.0065262F%40notes.na.collabserv.com.
