Use of Python scheduled task apscheduler

apscheduler Use

We can't avoid using some scheduled tasks in our projects , For example, recent projects , After users click to register for the exam, they need to push a small program message to remind customers on wechat when the exam date is approaching , Turn over fastapi In the implementation of , Although there are many methods and packages , But either it's too heavy （ For example, you need to open another service , Also rely on redis, It's not easy to use ）, Although it can also be used time Modular time.sleep() On board fastapi The background task of is realized in disguise , But the relatively simple function is OK , Complex code is troublesome , So we'd better assign someone to find a bag responsible for this amount . Look around and find out APScheduler It's quite suitable , The code is simple , The implementation effect is also very good , Here's a record ！
install

pip install apscheduler

Major component

Conceptual stuff , I'm familiar with you , Code is easier to understand than these definitions .

trigger (trigger) Contains scheduling logic , Each job has its own trigger , Used to decide which job will run next . Except for their own initial configuration , Triggers are completely stateless . Speaking human is the way you specify to trigger the current task .
type explain
DateTrigger Due execution ( To xxxx year x month x Japan x when x branch x Seconds to perform ) Corresponding DateTrigger
IntervalTrigger Interval execution （ Every time 5 Once per second ）
CronTrigger One crontab Conditions of type （ This is more complicated , For example, Monday to Thursday 4-5 Dot per hour 5 Once per second ）
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Job storage (job store) Store scheduled jobs , The default job store is simply to save jobs in memory , Other job stores store jobs in databases . The data of a job is serialized when it is stored in a persistent job store , And is deserialized on load . The scheduler cannot share the same job store .

Jobstore stay scheduler In the initialization , In addition, it can also be through scheduler Of add_jobstore Dynamic addition Jobstore. Every jobstore
Will be bound to a alias,scheduler stay Add Job when , According to the designation jobstore stay scheduler Find the corresponding jobstore, and
take job Add to jobstore in .

Jobstore Mainly through pickle Library loads and dumps【 The core of the implementation is through python Of __getstate__ and __setstate__ rewrite
Realization 】, Each change will Job Save to dynamic storage , When in use, it will be loaded dynamically , As storage can be redis, It's fine too
It's the database 【 adopt sqlarchemy This library integrates multiple databases 】, It can also be mongodb etc.
at present APScheduler Supported by Jobstore：

MemoryJobStore
MongoDBJobStore
RedisJobStore
RethinkDBJobStore
SQLAlchemyJobStore
ZooKeeperJobStore

actuator (executor) Process the run of the job , They usually submit the specified callable objects to a thread or pool in the job . When the work is done , The actuator will inform the scheduler .