APScheduler running one thread in local server, two threads when deployed remotely

Question

I have a Flask webserver that interacts with a POSTGREsql database to fetch and insert data from the website.

I also have an APScheduler Background Scheduler task that checks the database regularly, looks for certain objects with certain attributes like 5 minutes past creation, column x is over 10 etc, then sends that information in an email.

The problem I'm running into right now is that, when run in the local environment, only one task is executed, and it runs every (30) seconds like I want it to. However, if I deploy it on Heroku, two of the same tasks is executed within milliseconds of each other, and it causes problems.

The code responsible for running the background task would be this.

app = Flask(__name__)
#app.debug = True
app.debug = False
app.config.from_pyfile('config.py')
db = models.db
db.init_app(app)
migrate = Migrate(app, db)


manager = Manager(app)
manager.add_command('db', MigrateCommand)
job_defaults = {
    'coalesce': False,
    'max_instances': 1
}
sched = BackgroundScheduler(job_defaults=job_defaults)
sched.start()


@sched.scheduled_job('interval', seconds=30)
def my_job():
    with app.app_context():
        my_class = OutageCheck(db)
        my_class.checkOutage()

Are you running on multiple dynamos on Heroku or just one dynamo? — Sean Vieira, Aug 24 '15 at 20:44
@SeanVieira : One dynamo, and the logs show that it's coming from the same dynamo — lonewaft, Aug 24 '15 at 21:51
And how are you running the app on Heroku (`app.run` or some other WSGI server)? — Sean Vieira, Aug 25 '15 at 01:02
Have you read this? https://devcenter.heroku.com/articles/clock-processes-python — Alex Grönholm, Aug 25 '15 at 21:41

score 0 · Answer 1 · edited May 23 '17 at 11:52

0

It can be a reloader which runs 2 instances of flask on remote server. You can try this

app.run(debug=True, use_reloader=False)

Consult this question How to stop Flask from initialising twice in Debug Mode?

edited May 23 '17 at 11:52

Community

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answered Sep 01 '15 at 10:38

Alexey Smirnov

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APScheduler running one thread in local server, two threads when deployed remotely

1 Answers1