问为什么图形窗口在大约5秒后就会冻结？

EN

import threading
import pygame
import enum

# Window size
WINDOW_WIDTH  = 200
WINDOW_HEIGHT = 200

DARK    = (  50, 50, 50 )
WHITE   = ( 255,255,255 )
RED     = ( 255, 55, 55 )
GREEN   = (   5,255, 55 )
BLUE    = (   5, 55,255 )


colour_cycle = [ DARK, WHITE, RED, GREEN, BLUE ]


class UserEvents( enum.IntEnum ):
    CLIENT_NUMBER = pygame.USEREVENT + 1
    CLIENT_QUIT   = pygame.USEREVENT + 2
    # ...



class ConsoleInputThread( threading.Thread ):
    """ A thread that handles user input on the console.
        Waits for user input, then posts messages
        to the main PyGame thread for processing """
    def __init__( self, prompt ):
        threading.Thread.__init__(self)
        self.daemon         = True # exit with parent
        self.done           = False
        self.prompt         = prompt

    def stop( self ):
        self.done = True

    def run( self ):
        """ Loops until the user hangs-up """
        while ( not self.done ):
            # Get some input from the user
            user_input = input( self.prompt ).strip()
            new_event = None
            if ( user_input == 'quit' ):
                new_event = pygame.event.Event( UserEvents.CLIENT_QUIT, { } )
            else:
                try:
                    user_input = int( user_input )
                    new_event = pygame.event.Event( UserEvents.CLIENT_NUMBER, { "value":user_input } )
                except:
                    print( "Syntax Error" )
            # If we received valid input post it to the main thread
            if ( new_event ):
                pygame.event.post( new_event )




###
### MAIN
###

# Create the window
pygame.init()
pygame.display.set_caption("Socket Messages")
SURFACE = pygame.HWSURFACE|pygame.DOUBLEBUF|pygame.RESIZABLE
WINDOW  = pygame.display.set_mode( ( WINDOW_WIDTH, WINDOW_HEIGHT ), SURFACE )


# Start the console-input thread
input_thread = ConsoleInputThread( "How many people would you like to have: " )
input_thread.start()

# Main paint / update / event loop
done = False
clock = pygame.time.Clock()
colour_index = 0
while ( not done ):

    for event in pygame.event.get():
        if ( event.type == pygame.QUIT ):
            done = True

        elif ( event.type == UserEvents.CLIENT_QUIT ):
            print("\nCLIENT ASKED TO QUIT " )
            done = True

        elif ( event.type == UserEvents.CLIENT_NUMBER ):
            print( "\nVALUE WAS INPUT: %d " % ( event.value, ) )


    WINDOW.fill( colour_cycle[colour_index] )
    # rotate the colours, just so the screen changes
    colour_index += 1
    if ( colour_index >= len( colour_cycle ) ):
        colour_index = 0

    pygame.display.flip()

    clock.tick_busy_loop(2)  # NOTE: 2 frames per second, no flashy-flashy

input_thread.stop()
pygame.quit()