Scheduling Python Script to run every hour accurately

Question

Before I ask, Cron Jobs and Task Scheduler will be my last options, this script will be used across Windows and Linux and I'd prefer to have a coded out method of doing this than leaving this to the end user to complete.

Is there a library for Python that I can use to schedule tasks? I will need to run a function once every hour, however, over time if I run a script once every hour and use .sleep, "once every hour" will run at a different part of the hour from the previous day due to the delay inherent to executing/running the script and/or function.

What is the best way to schedule a function to run at a specific time of day (more than once) without using a Cron Job or scheduling it with Task Scheduler?

Or if this is not possible, I would like your input as well.

AP Scheduler fit my needs exactly.

Version < 3.0

import datetime
import time
from apscheduler.scheduler import Scheduler

# Start the scheduler
sched = Scheduler()
sched.daemonic = False
sched.start()

def job_function():
    print("Hello World")
    print(datetime.datetime.now())
    time.sleep(20)

# Schedules job_function to be run once each minute
sched.add_cron_job(job_function,  minute='0-59')

out:

>Hello World
>2014-03-28 09:44:00.016.492
>Hello World
>2014-03-28 09:45:00.0.14110

Version > 3.0

(From Animesh Pandey's answer below)

from apscheduler.schedulers.blocking import BlockingScheduler

sched = BlockingScheduler()

@sched.scheduled_job('interval', seconds=10)
def timed_job():
    print('This job is run every 10 seconds.')

@sched.scheduled_job('cron', day_of_week='mon-fri', hour=10)
def scheduled_job():
    print('This job is run every weekday at 10am.')

sched.configure(options_from_ini_file)
sched.start()

Answer 1

Maybe this can help: Advanced Python Scheduler

Here's a small piece of code from their documentation:

from apscheduler.schedulers.blocking import BlockingScheduler

def some_job():
    print "Decorated job"

scheduler = BlockingScheduler()
scheduler.add_job(some_job, 'interval', hours=1)
scheduler.start()

Answer 2

To run something every 10 minutes past the hour.

from datetime import datetime, timedelta

while 1:
    print 'Run something..'

    dt = datetime.now() + timedelta(hours=1)
    dt = dt.replace(minute=10)

    while datetime.now() < dt:
        time.sleep(1)

Answer 3

For apscheduler < 3.0, see Unknown's answer.

For apscheduler > 3.0

from apscheduler.schedulers.blocking import BlockingScheduler

sched = BlockingScheduler()

@sched.scheduled_job('interval', seconds=10)
def timed_job():
    print('This job is run every 10 seconds.')

@sched.scheduled_job('cron', day_of_week='mon-fri', hour=10)
def scheduled_job():
    print('This job is run every weekday at 10am.')

sched.configure(options_from_ini_file)
sched.start()

Update:

apscheduler documentation.

This for apscheduler-3.3.1 on Python 3.6.2.

"""
Following configurations are set for the scheduler:

 - a MongoDBJobStore named “mongo”
 - an SQLAlchemyJobStore named “default” (using SQLite)
 - a ThreadPoolExecutor named “default”, with a worker count of 20
 - a ProcessPoolExecutor named “processpool”, with a worker count of 5
 - UTC as the scheduler’s timezone
 - coalescing turned off for new jobs by default
 - a default maximum instance limit of 3 for new jobs
"""

from pytz import utc
from apscheduler.schedulers.blocking import BlockingScheduler
from apscheduler.jobstores.sqlalchemy import SQLAlchemyJobStore
from apscheduler.executors.pool import ProcessPoolExecutor

"""
Method 1:
"""
jobstores = {
    'mongo': {'type': 'mongodb'},
    'default': SQLAlchemyJobStore(url='sqlite:///jobs.sqlite')
}
executors = {
    'default': {'type': 'threadpool', 'max_workers': 20},
    'processpool': ProcessPoolExecutor(max_workers=5)
}
job_defaults = {
    'coalesce': False,
    'max_instances': 3
}

"""
Method 2 (ini format):
"""
gconfig = {
    'apscheduler.jobstores.mongo': {
        'type': 'mongodb'
    },
    'apscheduler.jobstores.default': {
        'type': 'sqlalchemy',
        'url': 'sqlite:///jobs.sqlite'
    },
    'apscheduler.executors.default': {
        'class': 'apscheduler.executors.pool:ThreadPoolExecutor',
        'max_workers': '20'
    },
    'apscheduler.executors.processpool': {
        'type': 'processpool',
        'max_workers': '5'
    },
    'apscheduler.job_defaults.coalesce': 'false',
    'apscheduler.job_defaults.max_instances': '3',
    'apscheduler.timezone': 'UTC',
}

sched_method1 = BlockingScheduler() # uses overrides from Method1
sched_method2 = BlockingScheduler() # uses same overrides from Method2 but in an ini format


@sched_method1.scheduled_job('interval', seconds=10)
def timed_job():
    print('This job is run every 10 seconds.')


@sched_method2.scheduled_job('cron', day_of_week='mon-fri', hour=10)
def scheduled_job():
    print('This job is run every weekday at 10am.')


sched_method1.configure(jobstores=jobstores, executors=executors, job_defaults=job_defaults, timezone=utc)
sched_method1.start()

sched_method2.configure(gconfig=gconfig)
sched_method2.start()

Answer 4

On the version posted by sunshinekitty called "Version < 3.0" , you may need to specify apscheduler 2.1.2 . I accidentally had version 3 on my 2.7 install, so I went:

pip uninstall apscheduler
pip install apscheduler==2.1.2

It worked correctly after that. Hope that helps.

Answer 5

The Python standard library does provide sched and threading for this task. But this means your scheduler script will have be running all the time instead of leaving its execution to the OS, which may or may not be what you want.

Answer 6

One option is to write a C/C++ wrapper that executes the python script on a regular basis. Your end-user would run the C/C++ executable, which would remain running in the background, and periodically execute the python script. This may not be the best solution, and may not work if you don't know C/C++ or want to keep this 100% python. But it does seem like the most user-friendly approach, since people are used to clicking on executables. All of this assumes that python is installed on your end user's computer.

Another option is to use cron job/Task Scheduler but to put it in the installer as a script so your end user doesn't have to do it.

Answer 7

   #For scheduling task execution
import schedule
import time

def job():
    print("I'm working...")

schedule.every(1).minutes.do(job)
#schedule.every().hour.do(job)
#schedule.every().day.at("10:30").do(job)
#schedule.every(5).to(10).minutes.do(job)
#schedule.every().monday.do(job)
#schedule.every().wednesday.at("13:15").do(job)
#schedule.every().minute.at(":17").do(job)

while True:
    schedule.run_pending()
    time.sleep(1)