Question

在python 2.7上

#!/usr/bin/env python
import time, threading, os
def f1(arg1):
    for i in xrange(arg1):
        time.sleep(1)
        print "i is: ", i
        print threading.enumerate()

if __name__ == '__main__':
    t = threading.Thread(name="MyThread1", target=f1, args=(5,))
    t.start()
    t.join()

$ ./threadeg.py

i is:  0
[<_MainThread(MainThread, started 140502713374464)>, <Thread(MyThread1, started 140502683985664)>]

i is:  1
[<_MainThread(MainThread, started 140502713374464)>, <Thread(MyThread1, started 140502683985664)>]

i is:  2
[<_MainThread(MainThread, started 140502713374464)>, <Thread(MyThread1, started 140502683985664)>]

i is:  3
[<_MainThread(MainThread, started 140502713374464)>, <Thread(MyThread1, started 140502683985664)>]

i is:  4
[<_MainThread(MainThread, started 140502713374464)>, <Thread(MyThread1, started 140502683985664)>]

问题：

为什么开始时间表明主线程在 MyThread1之后开始？即 MainThread_starttime - MyThread1_starttime＆gt; 0

Answer 1

输出没有说明首先启动了哪个线程，并且不清楚为什么你认为它会这样做。你在看140502713374464这样的整数吗？如果是这样，那些是Thread.ident()返回的值，与时间戳无关。只需查看Thread.__repr__()的代码：

def __repr__(self):
    assert self._initialized, "Thread.__init__() was not called"
    status = "initial"
    if self._started.is_set():
        status = "started"
    self.is_alive() # easy way to get ._is_stopped set when appropriate
    if self._is_stopped:
        status = "stopped"
    if self._daemonic:
        status += " daemon"
    if self._ident is not None:
        status += " %s" % self._ident
    return "<%s(%s, %s)>" % (self.__class__.__name__, self._name, status)

整数取自self._ident，它是平台为线程分配的任何唯一整数标识符的缓存值。

在更高级别，CPython在线程启动时不存储任何记录，因此您的示例输出不仅不会显示该信息，也不会显示任何其他信息。如果你想跟踪它，你需要自己实现它（例如，一个Thread子类捕获开始时间。）

Python哪个线程首先启动？

1 个答案: