ROS2: memory leak

Hi

when implementing the neopixel library in a ROS2 node, I get the following error:

```
Failed to create mailbox device
: Operation not permitted
Traceback (most recent call last):
File "/home/ubuntu/turtlebot3_ws/src/install/test_nodes/lib/test_nodes/ledSub", line 11, in
load_entry_point('test-nodes==0.0.0', 'console_scripts', 'ledSub')()
File "/home/ubuntu/turtlebot3_ws/src/install/test_nodes/lib/python3.8/site-packages/test_nodes/ledSub.py", line 82, in main
pixel_node = pixelNode()
File "/home/ubuntu/turtlebot3_ws/src/install/test_nodes/lib/python3.8/site-packages/test_nodes/ledSub.py", line 44, in __init__
self.pixels.show()
File "/usr/local/lib/python3.8/dist-packages/adafruit_pixelbuf.py", line 205, in show
return self._transmit(self._post_brightness_buffer)
File "/usr/local/lib/python3.8/dist-packages/neopixel.py", line 180, in _transmit
neopixel_write(self.pin, buffer)
File "/usr/local/lib/python3.8/dist-packages/neopixel_write.py", line 38, in neopixel_write
return _neopixel.neopixel_write(gpio, buf)
File "/usr/local/lib/python3.8/dist-packages/adafruit_blinka/microcontroller/bcm283x/neopixel.py", line 82, in neopixel_write
raise RuntimeError(
RuntimeError: ws2811_init failed with code -9 (Failed to create mailbox device)
swig/python detected a memory leak of type 'ws2811_t *', no destructor found.
```

This is my node:

```python
class pixelNode(Node):

def __init__(self, pixel_pin = board.D18, num_pixels = 34, ORDER = neopixel.GRB):
super().__init__('pixel_node')

self.subscription = self.create_subscription(
String,
'bot_state',
self.listener_callback,
10)
self.subscription # prevent unused variable warning
self.pixels = neopixel.NeoPixel(pixel_pin, num_pixels, brightness=0.5, auto_write=False, pixel_order=ORDER)
self.pixels.fill((255, 0, 0))
self.pixels.show()

# blue led blinker
timer_period = 0.5 # 2Hz
self.timer = self.create_timer(timer_period, self.timer_callback)

def listener_callback(self, msg):
if msg.data == 'driving':
self.pixels.fill((255, 255, 255))
self.get_logger().info('LEDS: DRIVING')

elif msg.data == 'detected':
self.pixels.fill((255, 127, 0))
self.get_logger().info('LEDS: DETECTED')

elif msg.data == 'shoot':
self.pixels.fill((255, 0, 255))
self.get_logger().info('LEDS: SHOOT')

else:
self.pixels.fill((255, 0, 0))
self.get_logger().info('LEDS: UNKNOWN')

self.pixels.show()

def timer_callback(self):
global bluestate

if bluestate == 0:
GPIO.output(25, GPIO.HIGH)
bluestate = 1
else:
GPIO.output(25, GPIO.LOW)
bluestate = 0
```

This is triggered when calling the function self.pixels.show(), which is inside a subscriber callback of a node.
Any idea how to solve?

ROS2 Foxy Ubuntu 20.04
Raspberry Pi 4
Similar issues:
https://github.com/jgarff/rpi_ws281x/issues/263
If I use the neopixel functions in a generic python script no issue arises. Thus the combination of ROS2 with neopixel is the issue
Thanks!

Start with test_nodes/ledSub.py at self.pixels.show(), then compare the ROS2 node with the standalone script that reportedly works. Read adafruit_blinka/microcontroller/bcm283x/neopixel.py and neopixel_write.py, and reproduce the mailbox error; done means identifying and documenting a confirmed fix or incompatibility for ROS2 Foxy on the Raspberry Pi.

Written by the indexing model from the issue text.