show code:

import os
import libvirt

libvirt.virEventRegisterDefaultImpl()

def openclose():
    c = libvirt.open('qemu:///system')
    c.close()


os.system('lsof -p %d | wc -l' % os.getpid())

for i in xrange(100):
    openclose()
    os.system('lsof -p %d | wc -l' % os.getpid())

explain:

https://www.redhat.com/archives/libvir-list/2013-September/msg00118.html