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Sched module in Python

  • Last Updated : 06 Feb, 2020

Sched module is the standard library, can be used in the creation of bots and other monitoring and automation applications. The sched module implements a generic event scheduler for running tasks at specific times. It provides similar tools like task scheduler in windows or Linux, but the main advantage is with Python’s own sched module platform differences can be ignored.

Example:




# 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)

Basic methods available with scheduler instances

  • scheduler.enter(): Events can be scheduled to run after a delay, or at a specific time. To schedule them with a delay, enter() method is used.

    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

    Example:






    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()

    Output :

    START: 1580389814.152131
    EVENT: 1580389815.1548214 1 st
    EVENT: 1580389816.1533117  2nd
    
  • scheduler.enterabs() The enterabs() time adds an event to the internal queue of the scheduler, as the run() method of a scheduler is called, the entries in the queue of a scheduler are executed one by one.

    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

    Example:




    # 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()

    Output :

    START: 1580389960.5845037
    EVENT: 1580389961.5875661 Event X
    
  • scheduler.cancel() Remove the event from the queue. If the event is not an event currently in the queue, this method will raise a 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()

    Output :

    START: 1580390119.54074
    EVENT: 1580390121.5439944  2nd
    
  • scheduler.empty() It return True if the event queue is empty. It takes no argument.

    Example:




    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()

    Output :

    START: 1580390318.1343799
    True
    False
    EVENT: 1580390320.136075 1 st
    
  • scheduler.queue Read-only attribute returning a list of upcoming events in the order they will be run. Each event is shown as a named tuple with the following fields: time, priority, action, argument, 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()

    Output :

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

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