Python dict memory issue

Question

I got an issue about memory on my application when adding a lot object into dict then removing out of dict. But it seem python does not free the allocated memory.

Please see my example code:

from memory_profiler import profile
from twisted.internet import reactor
class MyClass(object):
 def __init__(self):
 n = 10
 self.my_array = [[[0 for k in xrange(n)] for j in xrange(n)] for i in xrange(n)]
class TestClass(object):
 token_names = dict()
 counter = 0
 def add(self):
 self.counter = self.counter + 1
 self.token_names[str(self.counter)] = MyClass()
 def testrun(self):
 while True:
 if self.counter > 1000:
 self.remove()
 break
 self.add()
 @profile
 def remove(self):
 print("Remove " + str(len(self.token_names)))
 for k, v in self.token_names.items():
 del self.token_names[k]
 self.token_names.clear()
 @profile
 def start(self):
 self.testrun()
def main():
 test = TestClass()
 test.start()
 reactor.run()
if __name__ == '__main__':
 raise SystemExit(main())

When running this test, the memory growing up and does not free even the dict items were deleted from the dict after finish

But, if I modify the add() function to delete the newly added item from the dict likes that:

def add(self):
 self.counter = self.counter + 1
 self.token_names[str(self.counter)] = MyClass()
 del self.token_names[str(self.counter)]

The memory does not increase in this test.

So, I don't know if I'm missing anything in this example or anything is wrong?

Can you all please help me on this?

• metatoaster: This may be a possible related thread, along with this other one
• Trung: Thanks @metatoaster