Question

我有以下代码，并且陷入了while循环

我知道while datetime.datetime.now() < (datetime.datetime.now() + datetime.timedelta(minutes=wait_time)):行存在问题。

有人可以帮忙吗？

nodes_with_scanner = []
    wait_time = 60
    while datetime.datetime.now() < (datetime.datetime.now() + datetime.timedelta(minutes=wait_time)):
        nodes_with_scanner = get_nodes_with_scanner_in_dps(self.node_names, scanner_id, username=self.users[0].username)
        log.logger.debug("Number of pre-defined {0} scanners detected in DPS: {1}/{2}".format(scanner_type, len(nodes_with_scanner), len(self.node_names)))

        if state == "create":
            if len(self.node_names) == len(nodes_with_scanner):
                log.logger.debug("All {0} pre-defined scanners with id '{1}' have been successfully created in DPS for nodes '{2}'".format(scanner_type, scanner_id, ", ".join(self.node_names)))
                return
        elif state == "delete":
            if len(nodes_with_scanner) < 1:
                log.logger.debug("All {0} pre-defined scanners with id '{1}' have been successfully deleted in DPS for nodes '{2}'".format(scanner_type, scanner_id, ", ".join(self.node_names)))
                return
        log.logger.debug("Still waiting on some {0} pre-defined scanners to '{1}' in DPS; sleeping for 1 minute before next check".format(scanner_type, state))
        time.sleep(60)

Answer 1

您询问当前时间是否小于当前时间加上delta。当然，每次都会如此，未来总是会走得更远。

记录的开始时间：

start = datetime.datetime.now()
while datetime.datetime.now() < start + datetime.timedelta(minutes=wait_time)):

如果wait_time在循环中没有变化，请存储结束时间（当前时间加上delta）：

end = datetime.datetime.now() + datetime.timedelta(minutes=wait_time))
while datetime.datetime.now() < end:

在这里使用time.time()可能更容易：

end = time.time() + 60 * wait_time
while time.time() < end:

Answer 2

你在while循环中使用datetime.datetime.now()，这意味着你检查每次迭代是否现在的时间低于现在的时间+ delta。

这在逻辑上是错误的，因为它将永远是真的，因为现在的时间总是低于现在的时间加上delta。

您应该将其更改为：

time_to_start = datetime.datetime.now() 
while datetime.datetime.now() < (time_to_start + datetime.timedelta(minutes=wait_time)):
    print "do something"

Python .datetime.datetimenow（）和datetime.timedelta（）

2 个答案: