An example where serialization throws maximum recursion depth exceeded RuntimeError

serialisation.py

class Node():
	pass


nodes = []
for i in range( 100 ):
	n = Node()
	nodes.append( n )

for n in nodes:
	n.connections = set( nodes )
	n.connections.remove( n )

print len(nodes)

#Change the next two lines with dill, cloudpickle and pickle
import dill
try:
	dill.dump( n, open( 'file', 'wb' ) )
except RuntimeError as e:
	print e