join() on it to gracefully terminate when it's done with all the tasks. To not block the main thread of the program, we also used threading.Thread to start the scheduler and called. These IDs can be used to cancel events as demonstrated with scheduler.cancel(event_2_id). In this code snippet we can also see that. In that case, the event with highest priority (lowest number) goes first. The priority argument doesn't matter most of the time, but can be very important if 2 events are scheduled to happen at exactly the same time, yet they have to be executed sequentially. ![]() enter) receives 4 arguments, which are - delay in seconds ( in how many seconds will the event happen?), priority, name of the function to be called and optional function arguments. enter) events to be executed at later time. The code above defines scheduler, which is used to create (. # Event has to be canceled in main thread # delay in seconds -v v- priorityĮvent_1_id = scheduler.enter(2, 2, some_deferred_task, ('first',))Įvent_2_id = scheduler.enter(2, 1, some_deferred_task, ('second',)) # If first 2 events run at the exact same time, then "second" is ran firstĮvent_3_id = scheduler.enter(5, 1, some_deferred_task, ('third',)) Scheduler = sched.scheduler(time.time, time.sleep) One of the use cases for such deferred task can be scheduled shutdown or if you are're working with network connections or firewall you can create one-time job to revert changes in case you mess up and lock yourself out of the system. It works on all platforms, which might seem obvious, but will not necessarily be the case with all the libraries shown later. Sched is a very simple module, which can be used to schedule one-off tasks for some specified time - so, it's important to realise, that this is not recurring job (like cron job). Most of the time, Python standard library will contain solution to whatever problem you might have and if the problem is running deferred jobs like with Linux at command, then grabbing sched module might be the way to go. So, in this article I will give you an overview of all the options available to help you choose the right tool for the task at hand, as well as their use cases, including intro and basic examples to get you started quickly! The Builtin Solutionīefore exploring any external libraries, let's first check what we have in Pythons standard library. Whether you want to run simple deferred task, bunch of scheduled jobs or manage cron tabs, there's specialized library for that in Python. ![]() With Python there's always a lot of libraries and options for solving any particular problem and running scheduled or recurring jobs is no exception.
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