Issue 1:
Checklist

I have checked the issues list

for similar or identical bug reports.

I have checked the pull requests list

for existing proposed fixes.

I have checked the commit log

to find out if the bug was already fixed in the master branch.

I have included all related issues and possible duplicate issues in this issue

(If there are none, check this box anyway).

Related Issues and Possible Duplicates

Related Issues

None

Possible Duplicates

None

Description

In the latest version of the documentation about task_reject_on_worker_lost, it says Enabling this can cause message loops

But actually, enabling this will not cause message loops, tasks only execute twice.Tasks that have been redelivered will not be redelivered again, source code

Suggestions

If it is a documentation error, it is best to remove the warning from the document.

If the document is ok, it is need to modify the code.

I can help modify the document or code.

Issue 2:
Checklist

I have verified that the issue exists against the master branch of Celery.

This has already been asked to the discussion group first.

I have read the relevant section in the

contribution guide

on reporting bugs.

I have checked the issues list

for similar or identical bug reports.

I have checked the pull requests list

for existing proposed fixes.

I have checked the commit log

to find out if the bug was already fixed in the master branch.

I have included all related issues and possible duplicate issues

in this issue (If there are none, check this box anyway).

Mandatory Debugging Information

I have included the output of celery -A proj report in the issue.

(if you are not able to do this, then at least specify the Celery

version affected).

I have verified that the issue exists against the master branch of Celery.

I have included the contents of pip freeze in the issue.

I have included all the versions of all the external dependencies required

to reproduce this bug.

Optional Debugging Information

I have tried reproducing the issue on more than one Python version

and/or implementation.

I have tried reproducing the issue on more than one message broker and/or

result backend.

I have tried reproducing the issue on more than one version of the message

broker and/or result backend.

I have tried reproducing the issue on more than one operating system.

I have tried reproducing the issue on more than one workers pool.

I have tried reproducing the issue with autoscaling, retries,

ETA/Countdown & rate limits disabled.

I have tried reproducing the issue after downgrading

and/or upgrading Celery and its dependencies.

Related Issues and Possible Duplicates

Related Issues

https://groups.google.com/g/celery-users/c/VIyUHo0UHCM

Possible Duplicates

None

Environment & Settings

Celery version: 5.0.0

celery report Output:

Steps to Reproduce

Required Dependencies

Minimal Python Version: 3.7

Minimal Celery Version: 5.0.0

Minimal Kombu Version: 5.0.2

Minimal Broker Version: Redis 3.5.3

Minimal Result Backend Version: N/A or Unknown

Minimal OS and/or Kernel Version: Ubuntu 20.04

Minimal Broker Client Version: N/A or Unknown

Minimal Result Backend Client Version: N/A or Unknown

Python Packages

pip freeze Output:

Other Dependencies

N/A

Minimally Reproducible Test Case

from celery.decorators import periodic_task

@periodic_task(run_every=crontab(minute='*/10'))
def my-task():
doSomething()

Expected Behavior

Import from celery.decorators import periodic_task and use the periodic_task decorator on a task

Actual Behavior

Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/celery/utils/dispatch/signal.py", line 276, in send
response = receiver(signal=self, sender=sender, **named)
File "/usr/local/lib/python3.7/site-packages/vine/promises.py", line 160, in __call__
return self.throw()
File "/usr/local/lib/python3.7/site-packages/vine/promises.py", line 157, in __call__
retval = fun(*final_args, **final_kwargs)
File "/usr/local/lib/python3.7/site-packages/celery/app/base.py", line 640, in _autodiscover_tasks
return self._autodiscover_tasks_from_fixups(related_name)
File "/usr/local/lib/python3.7/site-packages/celery/app/base.py", line 653, in _autodiscover_tasks_from_fixups
], related_name=related_name)
File "/usr/local/lib/python3.7/site-packages/celery/app/base.py", line 645, in _autodiscover_tasks_from_names
packages() if callable(packages) else packages, related_name,
File "/usr/local/lib/python3.7/site-packages/celery/loaders/base.py", line 220, in autodiscover_tasks
related_name) if mod)
File "/usr/local/lib/python3.7/site-packages/celery/loaders/base.py", line 245, in autodiscover_tasks
return [find_related_module(pkg, related_name) for pkg in packages]
File "/usr/local/lib/python3.7/site-packages/celery/loaders/base.py", line 245, in <listcomp>
return [find_related_module(pkg, related_name) for pkg in packages]
File "/usr/local/lib/python3.7/site-packages/celery/loaders/base.py", line 270, in find_related_module
raise e
File "/usr/local/lib/python3.7/site-packages/celery/loaders/base.py", line 266, in find_related_module
return importlib.import_module(module_name)
File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
File "<frozen importlib._bootstrap>", line 983, in _find_and_load
File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/src/scraper/tasks.py", line 25, in <module>
@periodic_task(run_every=crontab(minute='*/10'))
File "/usr/local/lib/python3.7/site-packages/celery/local.py", line 403, in _compat_periodic_task_decorator
from celery.task import periodic_task
ModuleNotFoundError: No module named 'celery.task'
Traceback (most recent call last):
File "/usr/local/bin/celery", line 8, in <module>
sys.exit(main())
File "/usr/local/lib/python3.7/site-packages/celery/__main__.py", line 15, in main
sys.exit(_main())
File "/usr/local/lib/python3.7/site-packages/celery/bin/celery.py", line 150, in main
return celery(auto_envvar_prefix="CELERY")
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 829, in __call__
return self.main(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 782, in main
rv = self.invoke(ctx)
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 1259, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 1066, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 610, in invoke
return callback(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/click/decorators.py", line 21, in new_func
return f(get_current_context(), *args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/celery/bin/worker.py", line 329, in worker
**kwargs)
File "/usr/local/lib/python3.7/site-packages/celery/worker/worker.py", line 94, in __init__
self.app.loader.init_worker()
File "/usr/local/lib/python3.7/site-packages/celery/loaders/base.py", line 111, in init_worker
self.import_default_modules()
File "/usr/local/lib/python3.7/site-packages/celery/loaders/base.py", line 105, in import_default_modules
raise response
File "/usr/local/lib/python3.7/site-packages/celery/utils/dispatch/signal.py", line 276, in send
response = receiver(signal=self, sender=sender, **named)
File "/usr/local/lib/python3.7/site-packages/celery/fixups/django.py", line 82, in on_import_modules
self.worker_fixup.validate_models()
File "/usr/local/lib/python3.7/site-packages/celery/fixups/django.py", line 121, in validate_models
run_checks()
File "/usr/local/lib/python3.7/site-packages/django/core/checks/registry.py", line 70, in run_checks
new_errors = check(app_configs=app_configs, databases=databases)
File "/usr/local/lib/python3.7/site-packages/django/core/checks/urls.py", line 13, in check_url_config
return check_resolver(resolver)
File "/usr/local/lib/python3.7/site-packages/django/core/checks/urls.py", line 23, in check_resolver
return check_method()
File "/usr/local/lib/python3.7/site-packages/django/urls/resolvers.py", line 408, in check
for pattern in self.url_patterns:
File "/usr/local/lib/python3.7/site-packages/django/utils/functional.py", line 48, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/usr/local/lib/python3.7/site-packages/django/urls/resolvers.py", line 589, in url_patterns
patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "/usr/local/lib/python3.7/site-packages/django/utils/functional.py", line 48, in __get__
res = instance.__dict__[self.name] = self.func(instance)
File "/usr/local/lib/python3.7/site-packages/django/urls/resolvers.py", line 582, in urlconf_module
return import_module(self.urlconf_name)
File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
File "<frozen importlib._bootstrap>", line 983, in _find_and_load
File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/src/mydjango/urls.py", line 22, in <module>
path('api/', include('scraper.urls', namespace="scraper")),
File "/usr/local/lib/python3.7/site-packages/django/urls/conf.py", line 34, in include
urlconf_module = import_module(urlconf_module)
File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
File "<frozen importlib._bootstrap>", line 983, in _find_and_load
File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/src/scraper/urls.py", line 3, in <module>
from . import views
File "/src/scraper/views.py", line 2, in <module>
from .tasks import save_fuzzed_domains
File "/src/scraper/tasks.py", line 25, in <module>
@periodic_task(run_every=crontab(minute='*/10'))
File "/usr/local/lib/python3.7/site-packages/celery/local.py", line 403, in _compat_periodic_task_decorator
from celery.task import periodic_task
ModuleNotFoundError: No module named 'celery.task'