CODEWITHSUNDEEP
pythonweb2pyscheduler
MSR
MSR

Reputation: 173

Web2Py - configure a scheduler

I have an application written in Web2Py that contains some modules. I need to call some functions out of a module on a periodic basis, say once daily. I have been trying to get a scheduler working for that purpose but am not sure how to get it working properly. I have referred to this and this to get started.

I have got a scheduler.py class in the models directory, which contains code like this:

from gluon.scheduler import Scheduler
from Module1 import Module1

def daily_task():
module1 = Module1()
module1.action1(arg1, arg2, arg3)

daily_task_scheduler = Scheduler(db, tasks=dict(my_daily_task=daily_task))

In default.py I have following code for the scheduler:

def daily_periodic_task():
daily_task_scheduler.queue_task('daily_running_task', repeats=0, period=60)

[for testing I am running it after 60 seconds, otherwise for daily I plan to use period=86400]

In my Module1.py class, I have this kind of code:

   def action1(self, arg1, arg2, arg3):
    for row in db().select(db.table1.ALL):
        row.processed = 'processed'
        row.update_record()

One of the issues I am facing is that I don't understand clearly how to make this scheduler work to automatically handle the execution of action1 on daily basis. When I launch my application using syntax similar to: python web2py.py -K my_app it shows this in the console: web2py Web Framework Created by Massimo Di Pierro, Copyright 2007-2015 Version 2.11.2-stable+timestamp.2015.05.30.16.33.24 Database drivers available: sqlite3, imaplib, pyodbc, pymysql, pg8000 starting single-scheduler for "my_app"...

However, when I see the browser at: http://127.0.0.1:8000/my_app/default/daily_periodic_task

I just see "None" as text displayed on the screen and I don't see any changes produced by the scheduled task in my database table.

While when I see the browser at: http://127.0.0.1:8000/my_app/default/index

I get an error stating This web page is not available, basically indicating my application never got started.

When I start my application normally using python web2py.py my application loads fine but I don't see any changes produced by the scheduled task in my database table.

I am unable to figure out what I am doing wrong here and how to properly use the scheduler with Web2Py. Basically, I need to know how can I start my application normally alongwith the scheduled tasks properly running in background.

Any help in this regard would be highly appreciated.

Upvotes: 1

Views: 4780

Answers (1)

Anthony
Anthony

Reputation: 25536

Running python web2py.py starts the built-in web server, enabling web2py to respond to HTTP requests (i.e., serving web pages to a browser). This has nothing to do with the scheduler and will not result in any scheduled tasks being run.

To run scheduled tasks, you must start one or more background workers via:

python web2py.py -K myapp

The above does not start the built-in web server and therefore does not enable you to visit web pages. It simply starts a worker process that will be available to execute scheduled tasks.

Also, note that the above does not actually result in any tasks being scheduled. To schedule a task, you must insert a record in the db.scheduler_task table, which you can do via any of the usual methods of inserting records (including using appadmin) or programmatically via the scheduler.queue_task method (which is what you use in your daily_periodic_task action).

Note, you can simultaneously start the built-in web server and a scheduler worker process via:

python web2py.py -a yourpassword -K myapp -X

So, to schedule a daily task and have it actually executed, you need to (a) start a scheduler worker and (b) schedule the task. You can schedule the task by visiting your daily_periodic_task action, but note that you only need to visit that action once, as once the task has been scheduled, it remains in effect indefinitely (given that you have set repeats=0).

If the task does not appear to be working, it is possible there is something wrong with the task itself that is resulting in an error.

Upvotes: 3

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