def start_headless_x(display=None):
for _ in range(10):
chosen_display = display if display else pick_random_display()
headless_x = Popen(["Xvfb", chosen_display, "-ac"], stdout=PIPE, stderr=PIPE) # headless X
headless_x.display = chosen_display
time.sleep(0.5) # Give things time to crash
if headless_x.poll() is not None:
_, error = headless_x.communicate()
if "Server is already active" in error:
info("Server already running on %r." "Retrying on different display", chosen_display)
else:
raise Exception("Xvfb failed to start :%r" % error)
else:
info("Brought up headless X on display %r with pid %r", chosen_display, headless_x.pid)
log_output(headless_x.stderr)
log_output(headless_x.stdout)
return headless_x
else:
raise Exception("Failed to find a free display" " when spawning headless X")
