Python如何终止固定时间执行任务的scheduler调度器及对应线程？

方案1：改造现有sched实现（最小改动适配现有代码） #

sched.scheduler本身自带cancel()方法可以删除待执行的任务，任务清空后调度器的run()方法会自动退出，对应的线程也会自然终止，不需要暴力杀死线程。你只需要把调度器实例、待执行的事件实例、线程实例提前存到类属性里，方便后续调用取消逻辑即可。

修改后的代码示例 #

import sched
import time
import threading
import pytz

# 假设这是你的类
class FlightMonitor:
    def __init__(self, player):
        self.player = player
        # 存储当前运行的调度器、调度事件、监控线程
        self.current_scheduler = None
        self.current_event = None
        self.monitor_thread = None

    def stand_by(self, evt_time, number):
        """Waiting for scheduled time
        Starts a scheduler in a separate thread that will run in the background
        until a specific time is reached, usually a time in a flight's
        schedule. Once that specific time is reached, the program will regularly
        check if the state of the flight has changed as expected.
        
        Args:
        evt_time (:obj:`datetime`): The scheduled time of the status change.
        Schedulers need Unix timestamps, so this has to be converted
        inside the function.
        number (str): Flight number of the flight that should be observed.
        This function itself does not need it but it has to be passed on
        as an argument.
        """
        # 先取消之前正在运行的任务（如果存在）
        self.cancel_existing_task()

        # evt_time is given in UTC time but needs to be checked against
        # system time
        self.current_scheduler = sched.scheduler(time.time, time.sleep)
        tz = pytz.timezone(self.player.tz)

        # Turns the event time from datetime UTC into datetime player actual
        evt_time = pytz.utc.localize(evt_time).astimezone(tz)

        # Turns the datetime object into a UNIX time stamp
        evt_time = evt_time.timestamp()

        # 存储调度事件，后续取消用
        self.current_event = self.current_scheduler.enterabs(
            evt_time, 2, self.check_dep, [number])
        # 启动线程
        self.monitor_thread = threading.Thread(target=self.current_scheduler.run)
        self.monitor_thread.start()

    def cancel_existing_task(self):
        """取消当前正在等待的调度任务"""
        if self.current_scheduler and self.current_event:
            try:
                self.current_scheduler.cancel(self.current_event)
            except ValueError:
                # 事件已经执行或者已经被取消，忽略报错
                pass
        # 等待线程退出（可选，非必须）
        if self.monitor_thread and self.monitor_thread.is_alive():
            self.monitor_thread.join(timeout=1)
        # 重置属性
        self.current_scheduler = None
        self.current_event = None
        self.monitor_thread = None

    def check_dep(self, number):
        # 你的航班检查逻辑
        pass

当用户切换航班时，直接调用cancel_existing_task()方法即可终止之前的定时任务，再调用新的stand_by()传入新的航班参数即可。

方案2：使用threading.Timer（更简单，代码量更少） #

threading.Timer本身自带cancel()方法，你只需要把目标datetime转成时间戳，减去当前时间戳得到间隔秒数，就能直接用Timer实现你的需求，不需要自己维护scheduler。

代码示例 #

import threading
import time
import pytz

class FlightMonitor:
    def __init__(self, player):
        self.player = player
        self.current_timer = None

    def stand_by(self, evt_time, number):
        # 先取消旧任务
        self.cancel_existing_task()
        tz = pytz.timezone(self.player.tz)
        # 转换时区得到目标时间戳
        evt_time = pytz.utc.localize(evt_time).astimezone(tz).timestamp()
        # 计算距离当前的时间间隔
        delay = max(0, evt_time - time.time())
        # 启动Timer
        self.current_timer = threading.Timer(delay, self.check_dep, args=[number])
        self.current_timer.start()

    def cancel_existing_task(self):
        if self.current_timer:
            self.current_timer.cancel()
            self.current_timer = None

    def check_dep(self, number):
        # 你的航班检查逻辑
        pass

这个方案对初学者更友好，代码更简洁，不需要理解sched的调度逻辑，也能完全满足你的需求。

注意事项 #

• 如果目标时间已经过去，两种方案都会立刻执行检查逻辑，不会报错
• 取消操作不会影响已经开始执行的check_dep逻辑，如果需要中途中断正在运行的检查逻辑，可以额外加一个threading.Event标志位做判断

内容的提问来源于stack exchange，提问作者Syrus Drake