The second task takes a lot of time to complete, stress-testing the scheduler. The first one is scheduled with an interval of 0.1 seconds, and the second one is scheduled with an interval of 0.5 seconds. In this example, two tasks are scheduled for periodic execution. The call to run_loop() accepts an optinal parameter return_after, which allows the loop to return after a specified time, either as seconds or as a datetime.timedelta. When this event is set, run_loop() will cleanly return to the caller after completing the currently pending tasks. If the program needs to be able to cancel it, it should supply a stop_event, which is expected to be a threading.Event. If run_loop() is executed without parameters, it will continue running until the process is terminated. If the execution of a task is delayed so much that the next execution of the same task become pending, an execution will be skipped.Įxceptions during the execution are propagated out of run_loop()/ run_pending(), and can be dealt with by the caller. There is no build-up of delayed executions.All pending tasks will be executed as soon as possible after they become pending. Regardless of the load, no task will be completely starved.If more than one task become pending simultaneously, they will be executed in the order in which they were added to the schedule by schedule().Graceful handling of this condition is essential in a well-implemented periodic scheduler. For example, a task that is scheduled to run every second, could take more than a second to complete. Heavy loading means that there is not enough computer resources to execute all tasks as scheduled. Inside the run_loop method, ischedule calculates the time until the next task becomes pending, and idles the CPU until this happens. For example, if a task that takes 0.9 seconds to complete is scheduled to run every second, the execution number 1000 will happen exactly 1000 seconds after the start of the program (± a few milliseconds). Quite importantly, and unlike some other packages, ischedule takes into account the time it takes for the task function to execute. The project was originally made for an industrial automation and IoT application.īasic example from ischedule import schedule, run_loop def task_1 (): print ( "task 1" ) def task_2 (): print ( "task 2" ) schedule ( task_1, interval = 1.0 ) schedule ( task_2, interval = 0.2 ) run_loop () Simple syntax, precise timing, no busy waiting. Schedule periodic tasks in a Python program.
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