import sys
import gzip

class UnusedClass():
	def __init__(self,compressor):
		self.compressor = compressor
		pass

	def write(self, data):
		print("UnusedClass.write")

class Compressor():
	def __init__(self):
		print("Compressor.__init__")
		self.gz = gzip.GzipFile( 'debug.txt.gz', mode='wb')
		
		# COMMENT THIS OUT to make it work
		self.unused = gzip.GzipFile( fileobj=UnusedClass(self), mode='wb') # This creates an extra reference to this class

	def compressToFile(self,data):
		print("Compressor.compressToFile")
		self.gz.write(data)

contents = b"1234567890"

compressor = Compressor()
compressor.compressToFile(contents)

#sys.exit(0) # This breaks it in Py3