Queue.Queue() would not reduce capacity after get()

[yuan8421]

Hi @Windspar,
Thank you for reply and I thought your idea is great.
I did some experiment today. My observation is that the q size is empty, however the system memory is occupied about 84M. Here is some code to reproduce my result.
Ubuntu 16.04, python 2.7.12
First shoot: del

import Queue

q = Queue.Queue()
length = 10000000
buffer_size = 1000
index = 0
while index < length:
  q.put_nowait(1)
  index += 1
key = raw_input('finish insert, press key to pop')
while q.qsize() > buffer_size:
  a = q.get()
  del a
print 'after pop, q size = ', q.qsize()
raw_input('let me del the q')
del q
key = raw_input('finish delete')

Second shoot: clear()

import Queue

q = Queue.Queue()
length = 10000000
buffer_size = 1000
index = 0
while index < length:
  q.put_nowait(1)
  index += 1
key = raw_input('finish insert, press key to pop')
while q.qsize() > buffer_size:
  a = q.get()
  del a
print 'after pop, q size = ', q.qsize()
raw_input('let me del the q')
with q.mutex:
  q.queue.clear()
print 'q size = ', q.qsize()
key = raw_input('finish delete')

Third shoot: Queue()

import Queue

q = Queue.Queue()
length = 10000000
buffer_size = 1000
index = 0
while index < length:
  q.put_nowait(1)
  index += 1
key = raw_input('finish insert, press key to pop')
while q.qsize() > buffer_size:
  a = q.get()
  del a
print 'after pop, q size = ', q.qsize()
raw_input('let me del the q')
q = Queue.Queue()
print 'q size = ', q.qsize()
key = raw_input('finish delete')

Fourth shoot: gc.collect()

import Queue
import gc

q = Queue.Queue()
length = 10000000
buffer_size = 1000
index = 0
while index < length:
  q.put_nowait(1)
  index += 1
key = raw_input('finish insert, press key to pop')
while q.qsize() > buffer_size:
  a = q.get()
  del a
print 'after pop, q size = ', q.qsize()
raw_input('let me del the q')
#del q
#with q.mutex:
#  q.queue.clear()
q = Queue.Queue()
print 'q size = ', q.qsize()
raw_input('let me gc.collect')
gc.collect()
raw_input('how about now?')

These four ways would not release the memory in the queue.Can anyone tell me what I'm doing wrong? Many thanks!

http://effbot.org/pyfaq/why-doesnt-pytho...object.htm

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https://stackoverflow.com/questions/1545...-in-python

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You could try create a new queue. Swap it out for the old one. Clear old queue then del old queue.