总结python 三种常见的内存泄漏场景

i = 1024 ** 1024 ** 1024

In [1]: import sys                               

In [2]: a = {'name':'tom','age':16}                       

In [3]: sys.getrefcount(a)  # 由于 getrefcount 内部也会临时的引用 a 所以，使得计数器的值变成了 2 。               
Out[3]: 2

In [4]: b = a                                  

In [5]: sys.getrefcount(a)                           
Out[5]: 3

#!/usr/bin/evn python3

import sys
import time
import threading


class Person(object):
  free_lock = threading.Condition()

  def __init__(self, name: str = ""):
    """
    Parameters
    ----------
    name: str
      姓名

    best_friend: str
      最要好的朋友名
    """
    self._name = name
    self._best_friend = None

  @property
  def best_friend(self, person: "Person"):
    return self._best_friend

  @best_friend.setter
  def best_friend(self, friend: "Person"):
    self._best_friend = friend

  def __str__(self):
    """
    """
    return self._name

  def __del__(self):
    """
    """
    self.free_lock.acquire()
    print(f"{self._name} 要 GG 了，现在释放它的内存空间。")
    sys.stderr.flush()
    self.free_lock.release()


def mem_leak():
  """
  循环引用导致内存泄漏
  """
  zhang_san = Person(name='张三')
  li_si = Person("李四")

  # 构造出循环引用
  # 李四的好友是张三
  li_si.best_friend = zhang_san
  # 张三的好友是李四
  zhang_san.best_friend = li_si


if __name__ == "__main__":
  for i in range(3):
    time.sleep(0.01)
    print(f"{i}")
    mem_leak()

  print("mem_leak 执行完成了.")
  time.sleep(5)

In [1]: import sys                               

In [2]: import weakref                             

In [3]: from main import Person                         

In [4]: tom = Person('tom')                           

In [5]: sys.getrefcount(tom)                          
Out[5]: 2

In [6]: p = weakref.ref(tom)                          

In [7]: sys.getrefcount(tom)  # 弱引用不会增加计数器的值                        
Out[7]: 2

#!/usr/bin/evn python3


import sys
import time
import weakref
import threading


class Person(object):
  free_lock = threading.Condition()

  def __init__(self, name: str = ""):
    """
    Parameters
    ----------
    name: str
      姓名

    best_friend: str
      最要好的朋友名
    """
    self._name = name
    self._best_friend = None

  @property
  def best_friend(self, person: "Person"):
    return self._best_friend

  @best_friend.setter
  def best_friend(self, friend: "Person"):
    self._best_friend = weakref.ref(friend)

  def __str__(self):
    """
    """
    return self._name

  def __del__(self):
    """
    """
    self.free_lock.acquire()
    print(f"{self._name} 要 GG 了，现在释放它的内存空间。")
    sys.stderr.flush()
    self.free_lock.release()


def mem_leak():
  """
  循环引用导致内存泄漏
  """
  zhang_san = Person(name='张三')
  li_si = Person("李四")

  # 构造出循环引用
  # 李四的好友是张三
  li_si.best_friend = zhang_san
  # 张三的好友是李四
  zhang_san.best_friend = li_si


if __name__ == "__main__":
  for i in range(3):
    time.sleep(0.01)
    print(f"{i}")
    mem_leak()

  print("mem_leak 执行完成了.")
  time.sleep(5)