// in, it may lock up and prevent main from saying it's ready.
		"GOGC=off",
		// Set GODEBUG=asyncpreemptoff=1. If a thread is preempted
		// when it receives SIGQUIT, it won't show the expected
		// stack trace. See issue 35356.
		"GODEBUG=asyncpreemptoff=1",
	)

	var outbuf bytes.Buffer
	cmd.Stdout = &outbuf
	cmd.Stderr = &outbuf

	rp, wp, err := os.Pipe()

	// that do an os.Setenv in main.init or main.main.
	asynctimerchan atomic.Int32
}

var dbgvars = []*dbgVar{
	{name: "adaptivestackstart", value: &debug.adaptivestackstart},
	{name: "asyncpreemptoff", value: &debug.asyncpreemptoff},
	{name: "asynctimerchan", atomic: &debug.asynctimerchan},
	{name: "cgocheck", value: &debug.cgocheck},
	{name: "clobberfree", value: &debug.clobberfree},
	{name: "disablethp", value: &debug.disablethp},

	tracecheckstackownership: setting tracecheckstackownership=1 enables a debug check in the
	execution tracer to double-check stack ownership before taking a stack trace.

	asyncpreemptoff: asyncpreemptoff=1 disables signal-based
	asynchronous goroutine preemption. This makes some loops
	non-preemptible for long periods, which may delay GC and
	goroutine scheduling. This is useful for debugging GC issues

			// combination with the process-wide timer. Avoid double-counting.
			if validSIGPROF(nil, c) {
				sigprofNonGoPC(c.sigpc())
			}
			return
		}
		if sig == sigPreempt && preemptMSupported && debug.asyncpreemptoff == 0 {
			// This is probably a signal from preemptM sent
			// while executing Go code but received while
			// executing non-Go code.
			// We got past sigfwdgo, so we know that there is

			// after CASing the G back to _Grunning
			// because preemptM may be synchronous and we
			// don't want to catch the G just spinning on
			// its status.
			if preemptMSupported && debug.asyncpreemptoff == 0 && needAsync {
				// Rate limit preemptM calls. This is
				// particularly important on Windows
				// where preemptM is actually
				// synchronous and the spin loop here
				// can lead to live-lock.

	// Setting gp->stackguard0 to StackPreempt folds
	// preemption into the normal stack overflow check.
	gp.stackguard0 = stackPreempt

	// Request an async preemption of this P.
	if preemptMSupported && debug.asyncpreemptoff == 0 {
		pp.preempt = true
		preemptM(mp)
	}

	return true
}

var starttime int64

func schedtrace(detailed bool) {
	now := nanotime()
	if starttime == 0 {