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// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Tests a many interesting cases (network, syscalls, a little GC, busy goroutines,
// blocked goroutines, LockOSThread, pipes, and GOMAXPROCS).
//go:build ignore
package main
import (
"bytes"
"io"
"log"
"net"
"os"
"runtime"
"runtime/trace"
"sync"
"time"
)
func main() {
defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(8))
outerDone := make(chan bool)
go func() {
defer func() {
outerDone <- true
}()
var wg sync.WaitGroup
done := make(chan bool)
wg.Add(1)
go func() {
<-done
wg.Done()
}()
rp, wp, err := os.Pipe()
if err != nil {
log.Fatalf("failed to create pipe: %v", err)
return
}
defer func() {
rp.Close()
wp.Close()
}()
wg.Add(1)
go func() {
var tmp [1]byte
rp.Read(tmp[:])
<-done
wg.Done()
}()
time.Sleep(time.Millisecond)
go func() {
runtime.LockOSThread()
for {
select {
case <-done:
return
default:
runtime.Gosched()
}
}
}()
runtime.GC()
// Trigger GC from malloc.
n := 512
for i := 0; i < n; i++ {
_ = make([]byte, 1<<20)
}
// Create a bunch of busy goroutines to load all Ps.
for p := 0; p < 10; p++ {
wg.Add(1)
go func() {
// Do something useful.
tmp := make([]byte, 1<<16)
for i := range tmp {
tmp[i]++
}
_ = tmp
<-done
wg.Done()
}()
}
// Block in syscall.
wg.Add(1)
go func() {
var tmp [1]byte
rp.Read(tmp[:])
<-done
wg.Done()
}()
runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
// Test timers.
timerDone := make(chan bool)
go func() {
time.Sleep(time.Millisecond)
timerDone <- true
}()
<-timerDone
// A bit of network.
ln, err := net.Listen("tcp", "127.0.0.1:0")
if err != nil {
log.Fatalf("listen failed: %v", err)
return
}
defer ln.Close()
go func() {
c, err := ln.Accept()
if err != nil {
return
}
time.Sleep(time.Millisecond)
var buf [1]byte
c.Write(buf[:])
c.Close()
}()
c, err := net.Dial("tcp", ln.Addr().String())
if err != nil {
log.Fatalf("dial failed: %v", err)
return
}
var tmp [1]byte
c.Read(tmp[:])
c.Close()
go func() {
runtime.Gosched()
select {}
}()
// Unblock helper goroutines and wait them to finish.
wp.Write(tmp[:])
wp.Write(tmp[:])
close(done)
wg.Wait()
}()
const iters = 5
for i := 0; i < iters; i++ {
var w io.Writer
if i == iters-1 {
w = os.Stdout
} else {
w = new(bytes.Buffer)
}
if err := trace.Start(w); err != nil {
log.Fatalf("failed to start tracing: %v", err)
}
time.Sleep(time.Millisecond)
trace.Stop()
}
<-outerDone
}
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