Yes, this is a limitation of the current escape analysis. It doesn't realize that the proto.Buffer can be stack allocated. I suspect this is because b.Marshal is recursive, and escape analysis gives up on recursive things.
On Tuesday, March 7, 2017 at 8:22:42 PM UTC-8, apo...@google.com wrote: > > I'm guessing this is related to the same related questions about > "bytes.Buffer" and escape analysis. > > The golang protobuf package (https://github.com/golang/protobuf) has a > "proto.Buffer" type ( > https://github.com/golang/protobuf/blob/master/proto/lib.go#L309). > > The following program always heap allocates it: > > " > > package trial > > import ( > "log" > > "github.com/gogo/protobuf/proto" > > "google.golang.org/trial/codec_perf" // irrelevant protobuf code > generated by protoc compiler > ) > > func main() { > // protobuf struct here is irrelevant, any valid argument will cause > the behavior > p := &codec_perf.Buffer{} > > // b gets heap allocated > b := &proto.Buffer{} > > b.SetBuf(make([]byte, proto.Size(p))) > > if err := b.Marshal(p); err != nil { > log.Fatal(err) > } > } > > " > > > compiling with: 'go build -gcflags "-m=1"' > > > shows at the bottom of the log: > > > " > > # google.golang.org/trial > ./main.go:17: inlining call to (*proto.Buffer).SetBuf > ./main.go:17: make([]byte, proto.Size(p)) escapes to heap > ./main.go:17: p escapes to heap > ./main.go:12: &codec_perf.Buffer literal escapes to heap > ./main.go:15: &proto.Buffer literal escapes to heap > ./main.go:19: p escapes to heap > ./main.go:20: err escapes to heap > ./main.go:20: main ... argument does not escape > > " > > > FYI output of "go version": > > 'go version devel +4cce27a3fa Sat Jan 21 03:20:55 2017 +0000 linux/amd64' > > > > This might just be a golang/protobuf issue, but it also seems very similar to > https://github.com/golang/go/issues/7661. > > > > Wondering is this just due to escape analysis missing the opportunity? > Possibly heap allocs like this will go away in a future version? > > -- 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.
