switch len(ci.frames) {
	case 0: // In the rare case when there are no frames at all, we return Frame{}.
		return
	case 1:
		frame = ci.frames[0]
		ci.frames = ci.frameStore[:0]
	case 2:
		frame = ci.frames[0]
		ci.frameStore[0] = ci.frames[1]
		ci.frames = ci.frameStore[:1]
	default:
		frame = ci.frames[0]
		ci.frames = ci.frames[1:]
	}
	more = len(ci.frames) > 0
	if frame.funcInfo.valid() {

}

func main() {
	for i := 0; i <= 5; i++ {
		frames := testCallers(i)
		expected := expectedFrames[i]
		if !same(frames, expected) {
			fmt.Printf("testCallers(%d):\n got %v\n want %v\n", i, frames, expected)
		}

		frames = testCallersFrames(i)
		expected = allFrames[i:]
		if !same(frames, expected) {
			fmt.Printf("testCallersFrames(%d):\n got %v\n want %v\n", i, frames, expected)
		}
	}

	}

	frames := runtime.CallersFrames(pcs[:])
	frame, _ := frames.Next()

	inlined := frame.Func == nil // Func always set to nil for inlined frames
	if wantInlined != inlined {
		panic(fmt.Sprintf("caller %s inlined got %v want %v", frame.Function, inlined, wantInlined))
	}

	return runtime.FrameStartLine(&frame)

      reason: String,
    )
  }

  /**
   * Process the next protocol frame.
   *
   *  * If it is a control frame this will result in a single call to [FrameCallback].
   *  * If it is a message frame this will result in a single call to [FrameCallback.onReadMessage].
   *    If the message spans multiple frames, each interleaved control frame will result in a
   *    corresponding call to [FrameCallback].
   */

	// allocations are from the same leaf, so pick the first one.
	var firstLine int
	for ln := range allocObjects(records, frames[0]) {
		if firstLine == 0 || firstLine > ln {
			firstLine = ln
		}
	}
	for _, frame := range frames {
		var objectCount int64
		a := allocObjects(records, frame)
		for s := range size {
			// Allocations of size size[s] should be on line firstLine + s.
			ln := firstLine + s

				totalTraceSamples++
				if hogRegion != nil && ev.Goroutine() == hogRegion.Goroutine() {
					traceSamples++
					var fns []string
					ev.Stack().Frames(func(frame trace.StackFrame) bool {
						if frame.Func != "runtime.goexit" {
							fns = append(fns, fmt.Sprintf("%s:%d", frame.Func, frame.Line))
						}
						return true
					})
					stack := strings.Join(fns, "|")
					traceStacks[stack]++
				}
			}

Blocking APIs may be inefficient because you hold a thread idle while waiting on the network. Threads are expensive because they have both a memory overhead and a context-switching overhead.

#### Framed protocols

//export G1
func G1() {
	C.C2()
}

//export G2
func G2() {
	pc := make([]uintptr, 32)
	n := runtime.Callers(0, pc)
	cf := runtime.CallersFrames(pc[:n])
	var frames []runtime.Frame
	for {
		frame, more := cf.Next()
		frames = append(frames, frame)
		if !more {
			break
		}
	}

	want := []struct {
		function string
		line     int
	}{
		{"main.G2", 0},
		{"cFunction", 0x10200},

	}

	frames := f.dwarfSourceLine(addr)
	if frames != nil {
		return frames, nil
	}

	return nil, fmt.Errorf("no line information for PC=%#x", addr)
}

// dwarfSourceLine tries to get file/line information using DWARF.
// This is for C functions that appear in the profile.
// Returns nil if there is no information available.
func (f *file) dwarfSourceLine(addr uint64) []driver.Frame {

	lock.Lock()
	defer lock.Unlock()

	var pcs [50]uintptr
	nCallers := runtime.Callers(2, pcs[:])
	frames := runtime.CallersFrames(pcs[:nCallers])
	thisTest := ""
	for {
		frame, more := frames.Next()
		if strings.HasSuffix(frame.File, "_test.go") && testFunction.MatchString(frame.Function) {
			thisTest = frame.Function
			break
		}
		if !more {
			break
		}
	}

	if len(thisTest) == 0 {