Python program memory in windows

Question

Why after hide (minimize) the window the memory used of program is reduced?

example.py:

import time
while True:
    a = 2*2
    a = 0
    time.sleep(0.1)

after run in cmd (Windows XP, Python 2.7.9), used memory in task manager = 4 384 KB. after minimize console window used memory = 1 544 KB

Why is this happening? How to fix memory without hide window?

UPD: Solution: http://blog.in-orde.nl/content/memory-leak-using-com-objects-python-and-how-fix-it

Where did this information come from, and why is it important to you to minimzeyour memory usage, please? — holdenweb
– holdenweb, Commented Aug 6, 2015 at 9:28
Minimizing the window trims the number of pages in the process working set. You can do this programmatically via SetProcessWorkingSetSize. — Eryk Sun
– Eryk Sun, Commented Aug 6, 2015 at 9:39
You may prefer a ctypes solution that doesn't depend on PyWin32: import ctypes; kernel32 = ctypes.WinDLL('kernel32'); kernel32.GetCurrentProcess.restype = ctypes.c_void_p; kernel32.SetProcessWorkingSetSize.argtypes = (ctypes.c_void_p, ctypes.c_size_t, ctypes.c_size_t); kernel32.SetProcessWorkingSetSize(kernel32.GetCurrentProcess(), -1, -1). — Eryk Sun
– Eryk Sun, Commented Aug 6, 2015 at 9:58

Eryk Sun · Accepted Answer · 2015-08-06 13:42:05Z

2

Minimizing the window trims the number of pages in the process working set. You can do this programmatically via SetProcessWorkingSetSize. Here's an example using ctypes:

import ctypes
from ctypes import wintypes

kernel32 = ctypes.WinDLL('kernel32', use_last_error=True)

def errcheck_bool(result, func, args):
    if not result:
        raise ctypes.WinError(ctypes.get_last_error())
    return args

kernel32.GetCurrentProcess.restype = wintypes.HANDLE
kernel32.SetProcessWorkingSetSize.errcheck = errcheck_bool
kernel32.SetProcessWorkingSetSize.argtypes = (wintypes.HANDLE,
                                              ctypes.c_size_t,
                                              ctypes.c_size_t)

def trim_working_set():
    hProcess = kernel32.GetCurrentProcess()
    kernel32.SetProcessWorkingSetSize(hProcess, -1, -1)

answered Aug 6, 2015 at 13:42

Eryk Sun

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1 Comment

tsouchlarakis Over a year ago

This is very helpful. Would you be able to provide an example of how this could be used in the context of a Python script? I am attempting to query a very large dataset from a SQL server in a Windows environment using Python, without using 100% of the system's memory. Thank you.

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