test_subprocess.py 文件源码

def test_close_fds_after_preexec(self):
        fd_status = support.findfile("fd_status.py", subdir="subprocessdata")

        # this FD is used as dup2() target by preexec_fn, and should be closed
        # in the child process
        fd = os.dup(1)
        self.addCleanup(os.close, fd)

        p = subprocess.Popen([sys.executable, fd_status],
                             stdout=subprocess.PIPE, close_fds=True,
                             preexec_fn=lambda: os.dup2(1, fd))
        output, ignored = p.communicate()

        remaining_fds = set(map(int, output.split(b',')))

        self.assertNotIn(fd, remaining_fds)