autoreload.py 文件源码

def _reload():
    global _reload_attempted
    _reload_attempted = True
    for fn in _reload_hooks:
        fn()
    if hasattr(signal, "setitimer"):
        # Clear the alarm signal set by
        # ioloop.set_blocking_log_threshold so it doesn't fire
        # after the exec.
        signal.setitimer(signal.ITIMER_REAL, 0, 0)
    if sys.platform == 'win32':
        # os.execv is broken on Windows and can't properly parse command line
        # arguments and executable name if they contain whitespaces. subprocess
        # fixes that behavior.
        subprocess.Popen([sys.executable] + sys.argv)
        sys.exit(0)
    else:
        try:
            os.execv(sys.executable, [sys.executable] + sys.argv)
        except OSError:
            # Mac OS X versions prior to 10.6 do not support execv in
            # a process that contains multiple threads.  Instead of
            # re-executing in the current process, start a new one
            # and cause the current process to exit.  This isn't
            # ideal since the new process is detached from the parent
            # terminal and thus cannot easily be killed with ctrl-C,
            # but it's better than not being able to autoreload at
            # all.
            # Unfortunately the errno returned in this case does not
            # appear to be consistent, so we can't easily check for
            # this error specifically.
            os.spawnv(os.P_NOWAIT, sys.executable,
                      [sys.executable] + sys.argv)
            sys.exit(0)