Django APscheduler prevent more workers running scheduled task - django

Question

I use APScheduler in Django, on Windows IIS to run my background script. Problem is, taks gets run multiple times. If I run same program on my PC, it only runs once, but when I upload to windows server (which hosts my Django app) it runs more times. I guess it has some connection with the number of workers? Job is scheduled, but each time job task is done, it's like it runs random number of instances. First 1 time, then 2, then 10, then again 2. Even tho I have 'replace_existing=True, coalesce= True, misfire_grace_time = 1, max_instances = 1'
planer_zad.py
from apscheduler.schedulers.background import BackgroundScheduler
from blog.views import cron_mail_overdue
def start():
scheduler.add_job(cron_mail_overdue, "cron", hour=7, minute=14, day_of_week='mon-sun', id="task002", replace_existing=True, coalesce= True, misfire_grace_time = 10, max_instances = 1)
scheduler.start()
apps.py
from django.apps import AppConfig
class BlogConfig(AppConfig):
name = 'blog'
def ready(self):
#print('Starting Scheduler...')
from .planer import planer_zad
planer_zad.start()
For test I tried 'interval':
scheduler.add_job(cron_mail_overdue, "interval", minutes=1, id="task002", replace_existing=True, coalesce= True, misfire_grace_time = 10, max_instances = 1)
Tried:
scheduler = BackgroundScheduler({
'apscheduler.executors.default': {
'class': 'apscheduler.executors.pool:ThreadPoolExecutor',
'max_workers': '1'
},
'apscheduler.executors.processpool': {
'type': 'processpool',
'max_workers': '1'
},
'apscheduler.job_defaults.coalesce': 'True',
'apscheduler.job_defaults.max_instances': '1',
'apscheduler.timezone': 'UTC',
})
scheduler.add_job(cron_mail_overdue, "cron", hour=9, minute=3, second=00, day_of_week='mon-sun', id="task002", replace_existing=True, coalesce= True, misfire_grace_time = 10, max_instances = 1)
scheduler.start()
Does not work. Sometimes it runs only once, then 12 times.

Answer 1

Just test if the object already exists in ready() :
# django/myapp/apps.py
from django.apps import AppConfig
from apscheduler.schedulers.background import BackgroundScheduler
from apscheduler.triggers.cron import CronTrigger
class BlogConfig(AppConfig):
default_auto_field = 'django.db.models.BigAutoField'
name = 'blog'
def __init__(self, app_name, app_module):
super(BlogConfig, self).__init__(app_name, app_module)
self.planer_zad = None
def ready(self):
if os.environ.get('RUN_MAIN', None) != 'true':
return
if self.planer_zad is None:
background_scheduler = BackgroundScheduler()
background_scheduler.add_job(task1, CronTrigger.from_crontab('* * * * *')) # Every minutes (debug).
background_scheduler.start()
return background_scheduler
def task1(self):
print("cron task is working")
You can then call it later :
# api.py
from django.apps import apps
#router.get("/background-task")
def background_task(request):
"""
Run a background task.
"""
user = request.user
blog_config= apps.get_app_config('blog')
background_scheduler = blog_config.background_scheduler
return {"status": "Success", "True": str(background_scheduler)}