import glfw


glfw.init()
lastTime = glfw.get_time()
nbFrames = 0


def calc_fps(dt):
    global lastTime, nbFrames
    currentTime = glfw.get_time()
    nbFrames += 1
    if currentTime - lastTime >= 1.0:
        print(nbFrames)
        nbFrames = 0
        lastTime += 1.0

pyglet.clock.schedule(calc_fps)