threadcreate

examples/threadcreate/main.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"syscall"
+	"time"
+)
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	runtime.GOMAXPROCS(1)
+	n := 16
+	ch := make(chan int)
+	fmt.Printf("start work\n")
+	for i := 0; i < n; i++ {
+		go func() {
+			buf := make([]byte, 1024)
+			fmt.Printf("syscall\n")
+			n, err := syscall.Read(1, buf)
+			if err != nil {
+				panic(err)
+			}
+			fmt.Printf("%d\n", n)
+		}()
+		go dowork(ch)
+	}
+	runtime.GOMAXPROCS(8)
+	time.Sleep(50 * time.Millisecond)
+	runtime.GC()
+	if err := writeProfile("threadcreate"); err != nil {
+		return err
+	}
+	fmt.Printf("profile\n")
+	for i := 0; i < n; i++ {
+		fmt.Printf("%d\n", <-ch)
+	}
+	fmt.Printf("done\n")
+
+	return nil
+}
+
+func dowork(done chan int) {
+	s := 0
+	for i := 0; i < 1000000000; i++ {
+		if i%2 == 0 {
+			s++
+		}
+	}
+	done <- s
+}
+
+func writeProfile(name string) error {
+	f, err := os.Create(name + ".pb.gz")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	if err := pprof.Lookup(name).WriteTo(f, 0); err != nil {
+		return err
+	}
+	return nil
+}