del self vs self .__ del __() – 什么是在python中清理的正确

这个类有一个__del__方法用于常规清理.如果我在正常执行脚本期间删除了类,我想要完成一些清理工作.

我也有一个信号处理程序,它做了一些不寻常的清理工作.如果脚本在收到信号时正在执行其他操作,则需要进行一些额外的清理,然后进行常规清理.

我注意到做del self和self .__ del __()之间有区别.

也就是说,self .__ del __()调用del方法两次.

你能解释一下为什么会这样吗？

这是一个模拟脚本来说明问题：

import sys
import signal
from optparse import OptionParser


class TestClass(object):
    def __init__(self,del_self):
        self.del_self = del_self

        print "__init__ with del_self = %s" % self.del_self

    def __del__(self):
        print "Now performing usual cleanup."

    def signal_handler(self,arg_1,arg_2):
        print "Received signal. Now performing unusual cleanup."

        # Unusual cleanup

        print "Did unusual cleanup"

        if self.del_self:
            print("Doing del self")
            del self
        else:
            print("Doing self.__del__()")
            self.__del__()

        sys.exit(0)


if __name__ == '__main__':
    arguments = sys.argv[1:]
    parse = OptionParser("Test.")
    parse.add_option(
        "-d","--delself",help="Set del self.",type="int",default=1
    )

    (options,_) = parse.parse_args()

    print "Options: %s" % options

    tc = TestClass(del_self=options.delself)

    signal.signal(signal.SIGQUIT,tc.signal_handler)

    while True:
        pass

如果我运行脚本：

python deltest.py --delself 1

并发出killall -3 python我得到：

Received signal. Now performing unusual cleanup.
Did unusual cleanup
Doing del self
Now performing usual cleanup.

在哪里,如果我再次执行python deltest.py –delself 0后跟kill信号,我得到：

Received signal. Now performing unusual cleanup.
Did unusual cleanup
Doing self.__del__()
Now performing usual cleanup.
Now performing usual cleanup.

为什么__del__方法在这种情况下执行了两次？

谢谢！