Memory leak using Pin (callback)

[Colateral]

Hello,

LOPY 1.7.9.b3.

If you run this piece of code you will see that memory is decreasing ... in the end it stops with 'MemoryError: memory allocation failed' . Comparing to timer memory leak issue, I believe there is ALWAYS a LEAK when you are using function callbacks.

import gc
import utime
from machine import Pin


class Object:
    
    def __init__(self): 
        print ("Object INIT ", self)
        

    def start(self):    
        
        def _call(arg):
            print('PIN changed')
        
        self._analogPin=Pin('P15',mode=Pin.IN,pull=Pin.PULL_UP)    
        self._analogPin.callback(Pin.IRQ_FALLING , _call)
         
        
    def __del__(self):
        print ("Object DEL ", self)

    
    def stop(self):    
        self._analogPin.callback(Pin.IRQ_FALLING , None)
        del self._analogPin
        self._analogPin = None
        

print("Start memory %s" %(gc.mem_free()))

SLEEP = 0.1

gc.enable()
while True:
    obj = Object()
    obj.start()
    utime.sleep(SLEEP)
    obj.stop()
    del obj 
    obj = None
    
    gc.collect()
    print("\t\tmemory %s" %(gc.mem_free()))