import mmap, os
FILE = "/etc/passwd"

for x in range(10):
  f = file(FILE)
  m = mmap.mmap(f.fileno(), os.path.getsize(FILE), mmap.MAP_SHARED, mmap.PROT_READ)
  m.close()
  f.close()

os.system("lsof -p %d" % os.getpid())