// Start tracing.
	if err := trace.Start(os.Stdout); err != nil {
		log.Fatalf("failed to start tracing: %v", err)
	}
	// Run GOMAXPROCS a bunch of times, up and down.
	for i := 1; i <= 16; i *= 2 {
		runtime.GOMAXPROCS(i)
		time.Sleep(1 * time.Millisecond)
	}
	for i := 16; i >= 1; i /= 2 {
		runtime.GOMAXPROCS(i)
		time.Sleep(1 * time.Millisecond)
	}
	// Stop tracing.
	trace.Stop()

apiVersion: release-notes/v2
kind: feature
area: installation
releaseNotes:
- |

[GOOS:aix] env CGO_ENABLED=0  # go.dev/issue/56896
env GOMAXPROCS=16
go build -a -o http16.o net/http
env GOMAXPROCS=17
go build -a -o http17.o net/http
cmp -q http16.o http17.o
env GOMAXPROCS=18
go build -a -o http18.o net/http
cmp -q http16.o http18.o

# Check that goroutine scheduling does not affect linker output.
env GOMAXPROCS=16
go build -a -o gofmt16.exe cmd/gofmt
env GOMAXPROCS=17
go build -a -o gofmt17.exe cmd/gofmt

			panic(fmt.Sprintf("wlock(%d)\n", n))
		}
		for i := 0; i < 100; i++ {
		}
		atomic.AddInt32(activity, -10000)
		rwm.Unlock()
	}
	cdone <- true
}

func HammerRWMutex(gomaxprocs, numReaders, num_iterations int) {
	GOMAXPROCS(gomaxprocs)
	// Number of active readers + 10000 * number of active writers.
	var activity int32
	var rwm RWMutex
	rwm.Init()
	cdone := make(chan bool)

		t.Skip("skipping during short test")
	}
	maxprocs := runtime.GOMAXPROCS(3)
	compl := make(chan bool, 2)
	go func() {
		for i := 0; i != 1000; i += 1 {
			runtime.GC()
		}
		compl <- true
	}()
	go func() {
		for i := 0; i != 1000; i += 1 {
			runtime.GOMAXPROCS(3)
		}
		compl <- true
	}()
	go perpetuumMobile()
	<-compl
	<-compl
	stop <- true
	runtime.GOMAXPROCS(maxprocs)
}

	register("LockOSThreadAlt", LockOSThreadAlt)
}

func LockOSThreadMain() {
	// This requires GOMAXPROCS=1 from the beginning to reliably
	// start a goroutine on the main thread.
	if runtime.GOMAXPROCS(-1) != 1 {
		println("requires GOMAXPROCS=1")
		os.Exit(1)
	}

	ready := make(chan bool, 1)
	go func() {
		// Because GOMAXPROCS=1, this *should* be on the main
		// thread. Stay there.
		runtime.LockOSThread()

	// checks that the runtime doesn't do anything terrible.

	// This requires GOMAXPROCS=1 from the beginning to reliably
	// start a goroutine on the main thread.
	if runtime.GOMAXPROCS(-1) != 1 {
		println("requires GOMAXPROCS=1")
		os.Exit(1)
	}

	ready := make(chan bool, 1)
	go func() {
		// Because GOMAXPROCS=1, this *should* be on the main
		// thread. Stay there.
		runtime.LockOSThread()

// 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

		}
	}
	cdone <- true
}

// Borrowed from rwmutex_test.go
func hammerRWMutex(t *testing.T, gomaxprocs, numReaders, numIterations int) {
	t.Run(fmt.Sprintf("%d-%d-%d", gomaxprocs, numReaders, numIterations), func(t *testing.T) {
		resource := "test"
		runtime.GOMAXPROCS(gomaxprocs)
		// Number of active readers + 10000 * number of active writers.
		var activity int32
		cdone := make(chan bool)

import (
	"fmt"
	"reflect"
	"runtime"
	"strings"
	"testing"
)

func TestRandomScheduling(t *testing.T) {
	// Scheduler is most consistent with GOMAXPROCS=1.
	// Use that to make the test most likely to fail.
	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
	const N = 10
	out := make([][]int, N)
	for i := 0; i < N; i++ {
		c := make(chan int, N)
		for j := 0; j < N; j++ {
			go func(j int) {
				c <- j