How to implement Scheduler in Python ?

Lets understand How to implement Scheduler in Python . Lets start from the use case example – You must have seen so many database which are updated everyday basis like stock , weather etc . Imagine how tedious task is to call the same script every day manually . Good news is we can implement scheduler service in few lines of code in python and we can save tons of time . The beauty of scheduler service in python is that you may call it from any OS . Actually it may be implemented as python script so you have numerous ways for deployment .

Implement Scheduler in Python : Step by step –

1.Install  schedule package

pip install schedule

2. Create a job –

A job is nothing but the task you want to do through scheduler on a certain frequency. For this article we will create a function which will print some thing for us .

def call_me():
print("I am invoked")

3. Schedule the job-

schedule.every(30).seconds.do(call_me)

this will call the job at the frequency of 30 seconds . There are so many variation for frequency lets see one by one –

scheduling the job at some minutes interval –

schedule.every(10).minutes.do(call_me)

For scheduling every hour –

schedule.every().hour.do(call_me)

In case on a certain day at certain time-

schedule.every().tuesday.at("18:00").do(call_me)

4. Run the scheduler –

while True: 
  schedule.run_pending()

Complete code –

import schedule 
def call_me(): 
  print("I am invoked")
schedule.every(1).seconds.do(call_me)
while True: 
  schedule.run_pending()

Output –

As you see the implementation is done in a way that it will call call_me() function every second. This call_me function will print I am invoked every time . We are getting the same output –

I am invoked
I am invoked
I am invoked
I am invoked
I am invoked
I am invoked
I am invoked
I am invoked
I am invoked
I am invoked

There are several options and parameter which can make scheduler implementation more flexible . Please refer the Scheduler official documentation . Here you will the complete details for each function in the schedule package .

Use scheduler as a decorator –

As  a developer when you have to run multiple jobs in schedule . You may define a decorator function which you may apply on any job at any time . This will save lot of time and code redundancy . Lets understand how –

Create a decorator function for scheduler –

def scheduler(fun):
    def inner():
        schedule.every(7).seconds.do(fun)
        print("scheduled now")
        return
    return inner

Here fun is the function/job which is scheduled at every 7 seconds. Few more things here the function schedule will be attached with the function fun as a decorator symbol @. For example-

@schedule
def fun():
 print("I am a job")
 return

Please keep in the mind that the function name is schedule . This is not a python strict keyword .You may define your own keyword .

Alternative for Schedule package –

Obviously writing you own code is alternative for libraries . But there is no use of duplicate code still we do when we have license issue . If some one is charging for code or its commercial use  . Anyways there are few more options for scheduler in python . For example – Advanced Python Scheduler .

 

You may check it out as well.

Data Science Learner Team