delete(g.inSyscall, proc)
		}
	}
	// TODO(mknyszek): Consider modeling procs differently and have them be
	// transition to and from NotExist when GOMAXPROCS changes. We can emit
	// events for this to clearly delineate GOMAXPROCS changes.

	if viewerEv.Name != "" {
		ctx.Instant(viewerEv)
	}
}

func (g *procGenerator) Finish(ctx *traceContext) {
	ctx.SetResourceType("PROCS")

		// GODEBUG spoils program output, GOMAXPROCS makes it flaky.
		for _, env := range os.Environ() {
			if strings.HasPrefix(env, "GODEBUG=") ||
				strings.HasPrefix(env, "GOMAXPROCS=") ||
				strings.HasPrefix(env, "GORACE=") {
				continue
			}
			cmd.Env = append(cmd.Env, env)
		}
		cmd.Env = append(cmd.Env,
			"GOMAXPROCS=1", // see comment in race_test.go
			"GORACE="+test.gorace,
		)

	seen := make(map[int]bool)

	for v := range in {
		if _, ok := seen[v]; ok {
			println("got duplicate value: ", v)
			panic("fail")
		}
		seen[v] = true
	}
}

func main() {
	runtime.GOMAXPROCS(2)

	flag.Parse()
	c1 := make(chan int)
	c2 := make(chan int)
	c3 := make(chan int)
	c4 := make(chan int)
	done := make(chan bool)
	cmux := make(chan int)
	go sender(*iterations, c1, c2, c3, c4)

		the GC. Even if only one thread is running during the pause,
		this is computed as GOMAXPROCS times the pause latency because
		nothing else can be executing. This is the exact sum of samples
		in /sched/pauses/total/gc:seconds if each sample is multiplied
		by GOMAXPROCS at the time it is taken. This metric is an
		overestimate, and not directly comparable to system CPU time

	testHookUninstaller.Do(uninstallTestHooks)

	// The benchmark creates GOMAXPROCS client/server pairs.
	// Each pair creates 4 goroutines: client reader/writer and server reader/writer.
	// The benchmark stresses concurrent reading and writing to the same connection.
	// Such pattern is used in net/http and net/rpc.

	b.StopTimer()

	P := runtime.GOMAXPROCS(0)
	N := b.N / P
	W := 1000

	// Setup P client/server connections.

	lastUpdate atomic.Int64

	// lastEnabledCycle is the GC cycle that last had the limiter enabled.
	lastEnabledCycle atomic.Uint32

	// nprocs is an internal copy of gomaxprocs, used to determine total available
	// CPU time.
	//
	// gomaxprocs isn't used directly so as to keep this structure unit-testable.
	nprocs int32
}

// limiting returns true if the CPU limiter is currently enabled, meaning the Go GC

	if testing.Short() {
		t.Skip("skipping alloc test in short mode")
	}
	if race.Enabled {
		t.Skip("skipping test under race detector")
	}
	if runtime.GOMAXPROCS(0) > 1 {
		t.Skip("skipping; GOMAXPROCS>1")
	}
	n := testing.AllocsPerRun(100, func() {
		buf.Reset()
		testHeader.WriteSubset(&buf, nil)
	})
	if n > 0 {
		t.Errorf("allocs = %g; want 0", n)
	}
}

// the actual time spent paused, for orthogonality. maxProcs should be GOMAXPROCS,
// not work.stwprocs, since this number must be comparable to a total time computed
// from GOMAXPROCS.
func (s *cpuStats) accumulateGCPauseTime(dt int64, maxProcs int32) {
	cpu := dt * int64(maxProcs)
	s.GCPauseTime += cpu
	s.GCTotalTime += cpu
}

// trigger a GC cycle such that no GC assists are required to finish on time.
// This algorithm thus optimizes GC CPU utilization to the dedicated background
// mark utilization of 25% of GOMAXPROCS by minimizing GC assists.
// GOMAXPROCS. The high-level design of this algorithm is documented
// at https://github.com/golang/proposal/blob/master/design/44167-gc-pacer-redesign.md.

	// To help debugging, immediately log version
	klog.Infof("Version: %+v", version.Get())

	klog.InfoS("Golang settings", "GOGC", os.Getenv("GOGC"), "GOMAXPROCS", os.Getenv("GOMAXPROCS"), "GOTRACEBACK", os.Getenv("GOTRACEBACK"))

	config, err := NewConfig(opts)
	if err != nil {
		return err
	}
	completed, err := config.Complete()
	if err != nil {
		return err
	}