Understanding the go runtime (Golab)

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RUNTIME

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Introduction

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Disclaimer

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The Go RUNTIME (1.21)

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The Compiler

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The Go Compiler

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The Go Compiler

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How fast is Go? VS

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How fast is Go? VS package main func main() {} int main() {}

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How fast is Go? VS 1.2 MBs ~1 second/1000 executions 16 KBs ~0.3 second/1000 executions

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How fast is Go? 75 times binary size 3 times execution time

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Compiler ♥ Runtime

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The compiler and the go runtime tandem

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Hello world example package main import "fmt" func main() { fmt.Println("hello world!") }

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Our compiled hello world The Runtime The hello world

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Hello World Assembly 0x0000 00000 (.../main.go:5) TEXT main.main(SB), ABIInternal, $64-0 0x0000 00000 (.../main.go:5) CMPQ SP, 16(R14) 0x0004 00004 (.../main.go:5) PCDATA $0, $-2 0x0004 00004 (.../main.go:5) JLS 82 0x0006 00006 (.../main.go:5) PCDATA $0, $-1 0x0006 00006 (.../main.go:5) PUSHQ BP 0x0007 00007 (.../main.go:5) MOVQ SP, BP 0x000a 00010 (.../main.go:5) SUBQ $56, SP 0x000e 00014 (.../main.go:5) FUNCDATA $0, gclocals·g2BeySu+wFnoycgXfElmcg==(SB) 0x000e 00014 (.../main.go:5) FUNCDATA $1, gclocals·EaPwxsZ75yY1hHMVZLmk6g==(SB) 0x000e 00014 (.../main.go:5) FUNCDATA $2, main.main.stkobj(SB) 0x000e 00014 (.../main.go:6) MOVUPS X15, main..autotmp_8+40(SP) 0x0014 00020 (.../main.go:6) LEAQ type:string(SB), DX 0x001b 00027 (.../main.go:6) MOVQ DX, main..autotmp_8+40(SP) 0x0020 00032 (.../main.go:6) LEAQ main..stmp_0(SB), DX 0x0027 00039 (.../main.go:6) MOVQ DX, main..autotmp_8+48(SP) 0x002c 00044 (/usr/local/go/src/fmt/print.go:314) MOVQ os.Stdout(SB), BX 0x0033 00051 () NOP 0x0033 00051 (/usr/local/go/src/fmt/print.go:314) LEAQ go:itab.*os.File,io.Writer(SB), AX 0x003a 00058 (/usr/local/go/src/fmt/print.go:314) LEAQ main..autotmp_8+40(SP), CX 0x003f 00063 (/usr/local/go/src/fmt/print.go:314) MOVL $1, DI 0x0044 00068 (/usr/local/go/src/fmt/print.go:314) MOVQ DI, SI 0x0047 00071 (/usr/local/go/src/fmt/print.go:314) PCDATA $1, $0 0x0047 00071 (/usr/local/go/src/fmt/print.go:314) CALL fmt.Fprintln(SB) 0x004c 00076 (.../main.go:7) ADDQ $56, SP 0x0050 00080 (.../main.go:7) POPQ BP 0x0051 00081 (.../main.go:7) RET 0x0052 00082 (.../main.go:7) NOP 0x0052 00082 (.../main.go:5) PCDATA $1, $-1 0x0052 00082 (.../main.go:5) PCDATA $0, $-2 0x0052 00082 (.../main.go:5) CALL runtime.morestack_noctxt(SB) 0x0057 00087 (.../main.go:5) PCDATA $0, $-1 0x0057 00087 (.../main.go:5) JMP 0 Generated with: go build -gcflags=-S .

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Slices, Maps And Channels package main func main() { sampleSlice := []int{1, 2, 3, 4, 5} sampleSlice = append(sampleSlice, 6) sampleMap := map[string]int{"a": 1, "b": 2} sampleMap["c"] = 3 sampleChannel := make(chan int) for _, value := range sampleSlice { sampleChannel <- value } for _, value := range sampleMap { sampleChannel <- value } }

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Slices, Maps And Channels Assembly 0x0077 00119 (.../main.go:5) CALL runtime.growslice(SB) 0x00e3 00227 (.../main.go:7) CALL runtime.fastrand(SB) 0x010a 00266 (.../main.go:7) CALL runtime.mapassign_faststr(SB) 0x0131 00305 (.../main.go:7) CALL runtime.mapassign_faststr(SB) 0x0158 00344 (.../main.go:8) CALL runtime.mapassign_faststr(SB) 0x016d 00365 (.../main.go:10) CALL runtime.makechan(SB) 0x0199 00409 (.../main.go:13) CALL runtime.chansend1(SB) 0x01ea 00490 (.../main.go:16) CALL runtime.mapiterinit(SB) 0x020e 00526 (.../main.go:17) CALL runtime.chansend1(SB) 0x0220 00544 (.../main.go:16) CALL runtime.mapiternext(SB) 0x0239 00569 (.../main.go:3) CALL runtime.morestack_noctxt(SB) Generated with: go build -gcflags=-S .

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The Runtime

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The runtime

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The bootstrap process Stacks Pool TLS SYSARGS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Ps Start the World Enable GC Initial G sysmon Run Inits Your Code Start Main runtime/rt0_linux_amd64.s:7

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The Thread Local Storage Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV Your Code Start Main INIT GC Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/sys_linux_amd64.s:637

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Sysargs Stacks Pool TLS SYSARGS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV Your Code Start Main INIT GC Ps Start the World Enable GC Initial G sysmon Run Inits runtime/os_linux.go:232

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OS Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV Your Code Start Main INIT GC Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/os_linux.go:346

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The Scheduler Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV Your Code Start Main INIT GC Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:694

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The Scheduler ALL Ms ALL Ps ALL Gs M P SCHED M M P P

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Stop The World Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/lockrank_on.go:309

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Stacks Pool Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/stack.go:167

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Memory Allocator Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/malloc.go:375

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Memory Allocator package main func BenchmarkAlloc(b *testing.B) { slice := []int{} for 1 := 0; i < b.N; i++ { slice = make([]int, 1024) } _ = slice } int = 8 bytes, 8*1024 = 8192 8192 B/op 1 allocs/op package main func BenchmarkAlloc(b *testing.B) { slice := []int{} for 1 := 0; i < b.N; i++ { slice = make([]int, 1025) } _ = slice } int = 8 bytes, 8*1025 = 8200 ???? B/op 1 allocs/op

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MSPAN 8B Memory Allocator Page (8192B) Page (8192B) Page (8192B) … MSPAN 16B Page (8192B) Page (8192B) Page (8192B) … MSPAN 24B Page (8192B) Page (8192B) Page (8192B) … MSPAN 32B Page (8192B) Page (8192B) Page (8192B) … … MSPAN 32KB Page (8192B) Page (8192B) Page (8192B) … mcache … MHEAP Mcentral 8B … Mcentral 16B Mcentral 24B Mcentral 32B Mcentral 32KB P P P

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Memory Allocator package main func BenchmarkAlloc(b *testing.B) { slice := []int{} for 1 := 0; i < b.N; i++ { slice = make([]int, 1024*1024) } _ = slice } int = 8 bytes, 8*1024*1024 = 88388608 8388619 B/op 1 allocs/op package main func BenchmarkAlloc(b *testing.B) { slice := []int{} for 1 := 0; i < b.N; i++ { slice = make([]int, 1024*1024+1) } _ = slice } int = 8 bytes, 8*1024*1024+1 = 88388616 ??????? B/op 1 allocs/op

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CPU Flags Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:634

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AES Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/alg.go:312

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Random Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:884

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Main Thread Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:823

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Modules Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/symtab.go:452

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GO Args Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/runtime1.go:72

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GO Env Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/runtime1.go:82

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Secure Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/security_unix.go:9

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Debug Env Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/runtime1.go:367

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Too much info? Take a break. Look… here is a Kitten

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Init GC Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/mgc.go:184

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Init GC PACER SCAVENGER Sweeper FORCEGC GC

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Ps Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:5183

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Start The World Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:1280

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Initial G Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:144

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sysmon Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:5515

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sysmon SCAVENGER FORCEGC Netpoll Long running Gs Slow Syscalls Scheduler traces Sysmon

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Enable GC Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/mgc.go:197

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Run Inits Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:248

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Start Main Stacks Pool TLS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Your Code Start Main Ps Start the World Enable GC Initial G sysmon Run Inits SYSARGS runtime/proc.go:266

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During Runtime

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During running

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During running Garbage Collector Sysmon Scheduler Netpoll Your Code Ms Ps

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During running Slices, maps and channels operations Spawn goroutine Alloc Memory

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Summary

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Summary Stacks Pool TLS ARGS RANDOM Run CPU Flags OS Memory Allocator AES SCHED Stop the world Main thread Modules Go ARGS GO ENV Secure DEBUG ENV INIT GC Ps Start the World Enable GC Initial G sysmon Run Inits Your Code Start Main

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Summary 0x0077 00119 (.../main.go:5) CALL runtime.growslice(SB) 0x00e3 00227 (.../main.go:7) CALL runtime.fastrand(SB) 0x010a 00266 (.../main.go:7) CALL runtime.mapassign_faststr(SB) 0x0131 00305 (.../main.go:7) CALL runtime.mapassign_faststr(SB) 0x0158 00344 (.../main.go:8) CALL runtime.mapassign_faststr(SB) 0x016d 00365 (.../main.go:10) CALL runtime.makechan(SB) 0x0199 00409 (.../main.go:13) CALL runtime.chansend1(SB) 0x01ea 00490 (.../main.go:16) CALL runtime.mapiterinit(SB) 0x020e 00526 (.../main.go:17) CALL runtime.chansend1(SB) 0x0220 00544 (.../main.go:16) CALL runtime.mapiternext(SB) 0x0239 00569 (.../main.go:3) CALL runtime.morestack_noctxt(SB) Generated with: go build -gcflags=-S .

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The Illustrations of the Talk • Made by Juan de la Cruz for this talk • Creative Commons 0 (Use it however you want) • Downloadable in Penpot (Open Source Design tool) format • https://github.com/penpot/penpot-files/raw/main/Gopher-illustrations.penpot

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A Gift from Mattermost

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References • Memory Allocator: https://medium.com/@ankur_anand/a-visual-guide-to-golang-memory-allocator-f rom-ground-up-e132258453ed • The Garbage collector (Maya Rosecrance): https://youtu.be/gPxFOMuhnUU?si=O9pn99sLiqptgyw3 • The GC Pacer (Madhav Jivrajani): https://youtu.be/We-8RSk4eZA?si=QNXxqq2xVEoh9At9 • The memory allocator (Andre Carvalho): https://youtu.be/3CR4UNMK_Is?si=B0bUKHohbNq73t7V • The netpoll (Cindy Sridharan): https://youtu.be/xwlo3xigknI?si=dmTrK_CH_fa0Bs51 • The scheduler (Madhav Jivrajani): https://youtu.be/wQpC99Xu1U4?si=uOu0RiLyMpNXKYa0 • Other related talks from myself: ○ The go compiler: https://youtu.be/qnmoAA0WRgE?si=ANt-Mvm4hpR9Vydx ○ About goroutines: https://youtu.be/MYtUOOizITs?si=FVGFtez2z3fNCjx7