[python-win32] Memory Leak in Threaded COM Object [SEC=UNOFFICIAL]

[Andrew MacIntyre]

Stab in the dark:  after calling the Clear() method on object "tom" in method CreateTom, use "del tom" or "tom = None" to try and lose any remnant COM references before pythoncom.CoUninitialize() is called.

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Andrew MacIntyre           Operations Branch
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From: python-win32 [mailto:python-win32-bounces+andrew.macintyre=acma.gov.au at python.org] On Behalf Of Michael Watson
Sent: Saturday, 4 May 2013 8:05 AM
To: python-win32 at python.org
Subject: [python-win32] Memory Leak in Threaded COM Object


I am creating a COM client within a thread and performing several operations with this client. Each thread is spawned from a server that uses Python's socketserver module which has built-in threading support.

When I am loading and using this COM object there is an expected spike in memory usage by python.exe. With 10 concurrent threads there is a peak in memory usage of about 500Mb. However when the operations are finished and the COM object is apparently released, there are 50Mb of additional memory used by the process than before. If I then spawn 10 additional threads using the same server there are 13Mb additional used by python.exe after those COM objects are closed. Eventually every 10 additional concurrent threads adds approximately 6Mb after they are done. When I end the entire python.exe process, all the memory is released.

I have simplified the following code to mimic how the socketserver uses threadding and the problem is the exact same.

import win32com.client

import threading

import pythoncom



def CreateTom():

    pythoncom.CoInitialize()

    tom = win32com.client.Dispatch("TOM.Document")

    tom.Dataset.Load("FileName")

    tom.Clear()

    pythoncom.CoUninitialize()



for i in range(50):

    t = threading.Thread(target = CreateTom)

    t.daemon = False

    t.start()

I understand that I will unlikely get any support here around the specific COM library (it is an IBM product used in Market Research known as the TablesObjectModel). However I want to know if there is anything, ANYTHING, additional that I can do to release this memory. I have read about Apartments in COM but it sounds like pythoncom.CoInitialize should take care of this for me. Any help would be appreciated.

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