Sched module in Python

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