X gmigrate moved -> go123

go/gmigrate.go

-// gmigrate - show number of times G migrates to another M (OS thread).
-// usage: `go tool trace -d <trace.out> |gmigrate`
-
-// +build ignore
-
-package main
-
-
-import (
-	"bufio"
-	"errors"
-	"io"
-	"log"
-	"fmt"
-	"os"
-	"regexp"
-	"sort"
-	"strconv"
-	"strings"
-)
-
-// we analyze input stream and take notices on ProcStart and GoStart events.
-// when a ProcStart event comes, e.g.
-//
-//	9782014 ProcStart p=2 g=0 off=133138 thread=5
-//
-// we remember that a P is currently running on an M (=thread).
-//
-// when a GoStart event comes, e.g.
-//
-//	9782310 GoStart p=2 g=33 off=133142 g=33 seq=0
-//
-// we see that a G is using P to run, and by using previously noted P->M
-// relation, conclude G->M relation.
-//
-// Then for every G noticed we record how much it changes its M.
-
-type procStart struct {
-	p int
-	m int // =thread
-}
-
-type goStart struct {
-	g int
-	p int
-}
-
-// information about a G
-type gInfo struct {
-	g	 int
-	m        int // last time was running on this M
-	nmigrate int // how much times migrated between different Ms
-}
-
-func main() {
-	var pm = map[int]int{}		// p -> m
-	var gg = map[int]*gInfo{}	// g -> (m, #migrate)
-
-	in := bufio.NewReader(os.Stdin)
-
-	tstart, tend, tprev := -1, -1, -1
-	for lineno := 1;; lineno++{
-		bad := func(err error) {
-			log.Fatalf("%d: %v", lineno, err)
-		}
-		badf := func(format string, argv ...interface{}) {
-			bad(fmt.Errorf(format, argv...))
-		}
-
-		l, err := in.ReadString('\n')
-		if err != nil {
-			if err == io.EOF {
-				break
-			}
-			bad(err)
-		}
-		l = l[:len(l)-1] // strip trailing '\n'
-
-		t, evname, args, err := parseLineHeader(l)
-		if err != nil {
-			bad(err)
-		}
-
-		if t < tprev {
-			badf("time monotonity broken")
-		}
-		tprev = t
-
-		if tstart == -1 {
-			tstart = t
-		} else {
-			tend = t
-		}
-
-		switch evname {
-		case "ProcStart":
-			pstart, err := parseProcStart(args)
-			if err != nil {
-				bad(err)
-			}
-
-			pm[pstart.p] = pstart.m
-
-		case "GoStart":
-			gstart, err := parseGoStart(args)
-			if err != nil {
-				bad(err)
-			}
-
-			m, ok := pm[gstart.p]
-			if !ok {
-				badf("G%d start on P%d, but no matching previous P%d start",
-					gstart.g, gstart.p, gstart.p)
-			}
-
-			g, seen := gg[gstart.g]
-			if !seen {
-				gg[gstart.g] = &gInfo{g: gstart.g, m: m, nmigrate: 0}
-				break
-			}
-
-			if g.m != m {
-				g.m = m
-				g.nmigrate++
-			}
-		}
-	}
-
-	// all information collected - analyze
-	gv := make([]*gInfo, 0, len(gg))
-	for _, g := range gg {
-		gv = append(gv, g)
-	}
-
-	// order: (nmigrate, g)↓
-	sort.Slice(gv, func(i, j int) bool {
-		ni, nj := gv[i].nmigrate, gv[j].nmigrate
-		return (nj < ni) || (nj == ni && gv[j].g < gv[i].g) // reverse
-	})
-
-	fmt.Printf("G\tN(migrate)\tmigrate/s\n")
-	fmt.Printf("-\t----------\t---------\n")
-	for _, g := range gv {
-		fmt.Printf("G%d\t%8d\t%8.1f\n", g.g, g.nmigrate,
-			float64(g.nmigrate) / (float64(tend - tstart) * 1E-9))
-	}
-}
-
-// "9782014 ProcStart p=2 g=0 off=133138 thread=5"
-// ->
-// 9782014 "ProcStart" "p=2 g=0 off=133138 thread=5"
-func parseLineHeader(l string) (t int, event, args string, err error) {
-	sp := strings.IndexByte(l, ' ')
-	if sp < 0 {
-		return 0, "", "", fmt.Errorf("parse: invalid timestamp")
-	}
-	t, err = strconv.Atoi(l[:sp])
-	if err != nil {
-		return 0, "", "", fmt.Errorf("parse: invalid timestamp")
-	}
-
-	l = l[sp+1:]
-	sp = strings.IndexByte(l, ' ')
-	if sp < 0 {
-		return 0, "", "", fmt.Errorf("parse: invalid event name")
-	}
-
-	return t, l[:sp], l[sp+1:], nil
-}
-
-// ex: 9782014 ProcStart p=2 g=0 off=133138 thread=5
-var (
-	pStartArgvRe = regexp.MustCompile("^p=([^ ]+) g=[^ ]+ off=[^ ]+ thread=([^ ]+)$")
-	pStartArgvErr = errors.New("ProcStart: argv invalid")
-)
-
-func parseProcStart(args string) (procStart, error) {
-	argv := pStartArgvRe.FindStringSubmatch(args)
-	if argv == nil {
-		return procStart{}, pStartArgvErr
-	}
-
-	var pstart procStart
-	var err error
-	pstart.p, err = strconv.Atoi(argv[1])
-	if err != nil {
-		return procStart{}, pStartArgvErr
-	}
-
-	pstart.m, err = strconv.Atoi(argv[2])
-	if err != nil {
-		return procStart{}, pStartArgvErr
-	}
-
-	return pstart, nil
-}
-
-// ex: 9782310 GoStart p=2 g=33 off=133142 g=33 seq=0
-var (
-	gStartArgvRe = regexp.MustCompile("^p=([^ ]+) g=([^ ]+) off=[^ ]+ g=([^ ]+) seq=[^ ]+$")
-	gStartArgvErr = errors.New("GoStart: argv invalid")
-)
-
-func parseGoStart(args string) (goStart, error) {
-	argv := gStartArgvRe.FindStringSubmatch(args)
-	if argv == nil {
-		return goStart{}, gStartArgvErr
-	}
-
-	var gstart goStart
-	var err error
-	gstart.p, err = strconv.Atoi(argv[1])
-	if err != nil {
-		return goStart{}, gStartArgvErr
-	}
-
-	gstart.g, err = strconv.Atoi(argv[2])
-	if err != nil {
-		return goStart{}, gStartArgvErr
-	}
-
-	// double-check g is the same
-	g2, err := strconv.Atoi(argv[3])
-	if g2 != gstart.g {
-		log.Print("found GoStart with different g")
-		return goStart{}, gStartArgvErr
-	}
-
-	return gstart, nil
-}