在第二个SSH终端中运行第二个pygame程序（用于第二个显示）会暂停，直到按下^ C为止

Question

I have two displays on a Raspberry Pi 2 running Jessie: the (default) HDMI display, and an Adafruit PiTFT LCD.

I can start pygame programs independently in two SSH terminals, for two different displays, EXCEPT the 2nd one I run pauses until I hit ^C.

Using SSH on my Mac, I can run a 'count-to-50' pygame program on either one just fine. (The only difference is the LCD version sets 2 env variables that redirect pygame to the LCD screen.)

If I open two SSH terminals, and try to run both python programs, the second program only starts running if I press control-C.

What do I need to do differently so the second program starts running normally without first having to press control-C?

I'm not sure if this a "linux" device setup issue, a "python" code issue?

Here's the two simple programs:

# count_on_lcd.py
import pygame, time, os
# on raspberry pi this sends to LCD screen
os.environ['SDL_VIDEODRIVER'] = 'fbcon'
os.environ["SDL_FBDEV"] = "/dev/fb1"
pygame.init()
Screen = max(pygame.display.list_modes())
Surface = pygame.display.set_mode(Screen)
Surface.fill(pygame.Color(0,0,0))
pygame.display.update()
font_big = pygame.font.Font(None, 150)
for i in range(50):
  print (i)
  Surface.fill(pygame.Color(128,0,0))
  text_surface = font_big.render('%s'%i, True, (255,255,255))
  rect = text_surface.get_rect(center=(50,50))
  Surface.blit(text_surface, rect)
  pygame.display.update()
  time.sleep(1)
  Surface.fill(pygame.Color(0,128,0))
  pygame.display.update()
  time.sleep(1)

and

#count_on_hdmi.py
import pygame, time
# on raspberry pi the HDMI screne is default
pygame.init()
Screen = max(pygame.display.list_modes())
Surface = pygame.display.set_mode(Screen)
Surface.fill(pygame.Color(0,0,0))
pygame.display.update()
font_big = pygame.font.Font(None, 150)
for i in range(50):
  print (i)
  Surface.fill(pygame.Color(128,0,0))
  text_surface = font_big.render('%s'%i, True, (255,255,255))
  rect = text_surface.get_rect(center=(50,50))
  Surface.blit(text_surface, rect)
  pygame.display.update()
  time.sleep(1)
  Surface.fill(pygame.Color(0,128,0))
  pygame.display.update()
  time.sleep(1)

On my Mac, I open two SSH terminals to the Raspberry Pi.

In first SSH terminal:

$ sudo python count_on_lcd.py
(starts running normally)

In second SSH terminal:

$ sudo python count_on_hdmi.py
(Pauses until I type ^C)

It does the same thing regardless which order I start the two programs... the first command I invoke always runs immediately, the second command I invoke also requires a ^C before it will start running.

Answer 1

This seems to be an issue with pygame.init() not playing nicely if itls already running in a separate SSH terminal.

I found a solution on SO. It's not pretty but it works.

Only slightly modified from pygame requires keyboard interrupt to init display

from signal import alarm, signal, SIGALRM, SIGKILL

def init_Pygame(surf):

    # this section is an unbelievable nasty hack - for some reason Pygame
    # needs a keyboardinterrupt to initialise in some limited circs (second time running)
    class Alarm(Exception):
        pass

    def alarm_handler(signum, frame):
        raise Alarm

    signal(SIGALRM, alarm_handler)
    alarm(3)
    print("Step 2 ")
    try:
        pygame.init()
        Screen = max(pygame.display.list_modes())
        surf = pygame.display.set_mode(Screen)
        alarm(0)
    except Alarm:
        raise KeyboardInterrupt
    return (surf)