super-graph/docs/slides/highperf.slide

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2019-08-22 15:03:49 +02:00
High Performance Code in GO
GoTO, August 2019
Tags: GraphQL, API, GoLang, Postgres
Vikram Rangnekar
https://twitter.com/dosco
* About me
Co-founder of *movremote.com* a platform to connect developers with Silicon Valley
companies hiring remote.
Previously worked on Platform, Frontend and Ads @ Linkedin building the distributed targeting and serving infrastructure behind Linkedin Ads.
Also currently building Super Graph an open source instant GraphQL engine for Postgres and Rails. Written in GO
MOV Remote
.link https://movremote.com
Super Graph
.link https://supergraph.dev
* Why does it matter?
- Computer are not getting dramatically faster
- Our software is getting slower
- Demands on our software are increasing
- Scale of internet poducts is accelerating
- Faster = More money (For you)
* What does high performance mean?
- Code that runs fast (relative)
- Minimizes I/O latency
- Efficient in terms of GC
"Premature optimization is the root of all evil (or at least most of it) in programming."
-- Donald Knuth
"Measure twice cut once"
-- Someone
* Code that runs fast
1. Algorithm choices
2. Rewrite in GO
3. Reuse Memory
4. Parallelize I/O
4. Keep it simple
* Benchmarking
* $ benchcmp bench.1 bench.2
.image https://pbs.twimg.com/media/D8_uRFWU0AUdWkM?format=jpg&name=large _ 970
* Howto benchmark
Single threaded
func BenchmarkYourFunc(b *testing.B) {
for n := 0; n < b.N; n++ {
_, err := yourFunction(data)
...
}
}
Parallel
func BenchmarkYourFuncP(b *testing.B) {
b.RunParallel(func(pb *testing.PB) {
for pb.Next() {
_, err := yourFunction(data)
...
}
})
}
* Profileing Your Code
go test -bench=. -benchmem -memprofile mem.out -run=XXX
go tool pprof -cum mem.out
Get a nice command line
pkg: github.com/dosco/super-graph/psql
BenchmarkCompile-8 100000 15138 ns/op 3553 B/op 35 allocs/op
BenchmarkCompileParallel-8 300000 4760 ns/op 3583 B/op 35 allocs/op
PASS
ok github.com/dosco/super-graph/psql 3.174s
Type: alloc_space
Time: Aug 21, 2019 at 11:56am (EDT)
Entering interactive mode (type "help" for commands, "o" for options)
(pprof)
Powerful commands
top, web, png, pdf, ... and more
* Top - Shows you the top allocating functions
(pprof) top
Showing nodes accounting for 1.07GB, 77.92% of 1.37GB total
Showing top 10 nodes out of 34
flat flat% sum% cum cum%
0.01GB 0.89% 0.89% 1.11GB 80.77% github.com/[...]/qcode.(*Compiler).Compile
0 0% 0.89% 1.02GB 74.22% github.com/dosco/super-graph/
0.52GB 37.74% 38.63% 0.94GB 68.50% github.com/[...]/qcode.(*Compiler).compileQuery
0.54GB 39.29% 77.92% 0.54GB 39.29% github.com/dosco/super-graph/util.NewStack
Digging deeper
(pprof) top .compileQuery
focus=.compileQuery
Showing nodes accounting for 1006.59MB, 69.36% of 1451.18MB total
Showing top 10 nodes out of 26
flat flat% sum% cum cum%
0 0% 0% 1006.05MB 69.33% github.com/[...]/qcode.(*Compiler).Compile
579.44MB 39.93% 39.93% 1006.05MB 69.33% github.com/[...]/qcode.(*Compiler).compileQuery
* Cool Graphs
.image https://matoski.com/article/golang-profiling-flamegraphs/cpu-profile-graph-001.png 500 _
* Reducing Allocations - Part 1
Pre-allocate
m := make(map[string]someStruct{}, len(whatever))
mp := &m[i]
Work with bytes if possible
inlineToLower(&value) instead of bytes.ToLower(value)
Reuse Memory
var nodePool = sync.Pool{
New: func() interface{} { return new(Node) },
}
Use Builders
var b strings.Builder
b.WriteString("hello ");
b.WriteString("world")
* Reducing Allocations - Part 2
Use streaming (io.Reader and io.Writer)
r := strings.NewReader("some io.Reader stream to be read\n")
_, err := io.Copy(os.Stdout, r);
Allocate Together
type Node struct {
Children []Child
childA [5]Child
}
n := Node{}
n.Children = n.childA[:0]
Use 'Append' functions
strconv.AppendInt(b10, 42, 10) instead of strconv.FormatInt(42, 10)
* Reducing Allocations - Part 3
Use 'unsafe' if you know what you're doing
func bytesToString(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
* Squeezing out more performance
Avoid reflection use generators
Inlined Assembly (Crazy)
// add.go
package main
import "fmt"
func add(x, y int64) int64
func main() {
fmt.Println(add(2, 3))
}
// add_amd64.s
TEXT ·add(SB),NOSPLIT,$0
MOVQ x+0(FP), BX
MOVQ y+8(FP), BP
ADDQ BP, BX
MOVQ BX, ret+16(FP)
RET