Python中的调度模块

Sched模块是标准库，可用于创建机器人和其他监控和自动化应用程序。 sched 模块实现了一个通用的事件调度器，用于在特定时间运行任务。它提供了类似windows或Linux中任务调度器的工具，但主要优点是与Python自带的sched模块平台差异可以忽略。

例子：

# Python program for Creating 
# an event scheduler
  
  
import sched
import time
  
  
# Creating an instance of the
# scheduler class
scheduler = sched.scheduler(time.time, 
                            time.sleep)

调度程序实例可用的基本方法

• scheduler.enter()：可以安排事件在延迟后运行，或者在特定时间运行。要延迟安排它们，请使用enter()方法。
  

  Syntax: scheduler.enter(delay, priority, action, argument=(), kwargs={})

  Parameters:
  delay: A number representing the delay time
  priority: Priority value
  action: Calling function
  argument: A tuple of arguments

  例子：

  import sched
  import time
    
  # instance is created
  scheduler = sched.scheduler(time.time,
                              time.sleep)
    
  # function to print time 
  # and name of the event
  def print_event(name):
      print('EVENT:', time.time(), name)
    
  # printing starting time
  print ('START:', time.time())
    
  # first event with delay of
  # 1 second
  e1 = scheduler.enter(1, 1, 
                       print_event, ('1 st', ))
    
  # second event with delay of
  # 2 seconds
  e1 = scheduler.enter(2, 1, 
                       print_event, (' 2nd', ))
    
  # executing the events
  scheduler.run()
  

  输出 ：

  START: 1580389814.152131
  EVENT: 1580389815.1548214 1 st
  EVENT: 1580389816.1533117  2nd
  

• scheduler.enterabs() enterabs()时将一个事件添加到调度器的内部队列中，当调用调度器的run()方法时，调度器队列中的条目会被一一执行。
  

  Syntax: scheduler.enterabs(time, priority, action, argument=(), kwargs={})

  Parameters:
  time: Time at which the event/action has to be executed
  priority: The priority of the event
  action: The function that constitutes an event
  argument: Positional arguments to the event function
  kwargs: A dictionary of keyword arguments to the event function

  例子：

  # library imported
  import sched
  import time
    
  # instance is created
  scheduler = sched.scheduler(time.time,
                              time.sleep)
    
  # function to print time and
  # name of the event
  def print_event(name):
      print('EVENT:', time.time(), name)
    
  # printing starting time
  print ('START:', time.time())
    
  # event x with delay of 1 second
  # enters queue using enterabs method
  e_x = scheduler.enterabs(time.time()+1, 1,
                           print_event, 
                           argument = ("Event X", ));
    
  # executing the events
  scheduler.run()
  

  输出 ：

  START: 1580389960.5845037
  EVENT: 1580389961.5875661 Event X
  

• scheduler.cancel()从队列中移除事件。如果事件不是当前队列中的事件，则此方法将引发ValueError 。
  

  Syntax: scheduler.cancel(event)

  Parameter:
  event: The event that should be removed.

  import sched
  import time
    
    
  # instance is created
  scheduler = sched.scheduler(time.time,
                              time.sleep)
    
  # function to print time and
  # name of the event
  def print_event(name):
      print('EVENT:', time.time(), name)
    
  # printing starting time
  print ('START:', time.time())
    
  # first event with delay 
  # of 1 second
  e1 = scheduler.enter(1, 1, 
                       print_event,
                       ('1 st', ))
    
    
  # second event with delay 
  # of 2 seconds
  e2 = scheduler.enter(2, 1, 
                       print_event,
                       (' 2nd', ))
    
  # removing 1st event from 
  # the event queue
  scheduler.cancel(e1)
    
  # executing the events
  scheduler.run()
  

  输出 ：

  START: 1580390119.54074
  EVENT: 1580390121.5439944  2nd
  

• scheduler.empty()如果事件队列为空，则返回 True。它不需要争论。

  例子：

  import sched
  import time
    
    
  # instance is created
  scheduler = sched.scheduler(time.time,
                              time.sleep)
    
  # function to print time 
  # and name of the event
  def print_event(name):
      print('EVENT:', time.time(), name)
    
  # printing starting time
  print ('START:', time.time())
    
  # checking if event queue is
  # empty or not
  print(scheduler.empty())
    
  # event entering into queue
  e1 = scheduler.enter(2, 1,
                       print_event,
                       ('1 st', ))
    
  # checking if event queue is 
  # empty or not
  print(scheduler.empty())
    
  # executing the events
  scheduler.run()
  

  输出 ：

  START: 1580390318.1343799
  True
  False
  EVENT: 1580390320.136075 1 st
  

• scheduler.queue只读属性，按运行顺序返回即将发生的事件列表。每个事件都显示为具有以下字段的命名元组：时间、优先级、动作、参数、kwargs。

  # library imported
  import sched
  import time
    
  # instance is created
  scheduler = sched.scheduler(time.time,
                              time.sleep)
    
  # function to print time 
  # and name of the event
  def print_event(name):
      print('EVENT:', time.time(), name)
    
  # printing starting time
  print ('START:', time.time())
    
  # event entering into queue
  e1 = scheduler.enter(2, 1,
                       print_event, 
                       ('1 st', ))
    
  # printing the details of
  # upcoming events in event queue
  print(scheduler.queue)
    
  # executing the events
  scheduler.run()
  

  输出 ：

  START: 1580390446.8743565
  [Event(time=1580390448.8743565, priority=1, action=, argument=(‘1 st’, ), kwargs={})]
  EVENT: 1580390448.876916 1 st