Issue 1:
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

None

Possible Duplicates

None

Environment & Settings

Celery version: 5.1.0b1 (singularity)

celery report Output:

software -> celery:5.1.0b1 (singularity) kombu:5.1.0b1 py:3.8.5
billiard:3.6.4.0 py-amqp:5.0.6
platform -> system:Linux arch:64bit, ELF
kernel version:5.8.0-48-generic imp:CPython
loader -> celery.loaders.app.AppLoader
settings -> transport:amqp results:redis://localhost/

broker_url: 'amqp://guest:********@localhost:5672//'
result_backend: 'redis://localhost/'
deprecated_settings: None

Steps to Reproduce

Required Dependencies

Minimal Python Version: N/A or Unknown

Minimal Celery Version: N/A or Unknown

Minimal Kombu Version: N/A or Unknown

Minimal Broker Version: N/A or Unknown

Minimal Result Backend Version: N/A or Unknown

Minimal OS and/or Kernel Version: N/A or Unknown

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

import celery

app = celery.Celery(
broker='amqp://localhost',
backend='redis://localhost',
)

@app.task
def task_a(number):
print(f'Task A: {number}')
return number

@app.task
def task_b(number):
print(f'Task B: {number}')
return number

@app.task
def task_c(number):
print(f'Task C: {number}')

if __name__ == '__main__':
celery.chord(
(celery.chain(task_a.s(i), task_b.s()))
for i in range(3)
)(task_c.s()) # yapf: disable

app.start()

Expected Behavior

Expected output:

[2021-04-11 16:44:51,364: WARNING/ForkPoolWorker-15] Task A: 0
[2021-04-11 16:44:51,364: WARNING/ForkPoolWorker-16] Task A: 1
[2021-04-11 16:44:51,364: WARNING/ForkPoolWorker-1] Task A: 2
[2021-04-11 16:44:51,387: WARNING/ForkPoolWorker-4] Task B: 2
[2021-04-11 16:44:51,387: WARNING/ForkPoolWorker-3] Task B: 0
[2021-04-11 16:44:51,387: WARNING/ForkPoolWorker-2] Task B: 1
[2021-04-11 16:44:51,413: WARNING/ForkPoolWorker-15] Task C: [0, 1, 2]

On celery==5.0.5 it works fine

Actual Behavior

[2021-04-11 16:33:24,583: WARNING/ForkPoolWorker-15] Task A: 0
[2021-04-11 16:33:24,583: WARNING/ForkPoolWorker-1] Task A: 2
[2021-04-11 16:33:24,583: WARNING/ForkPoolWorker-16] Task A: 1
[2021-04-11 16:33:24,608: WARNING/ForkPoolWorker-4] Task B: 2
[2021-04-11 16:33:24,608: WARNING/ForkPoolWorker-2] Task B: 0
[2021-04-11 16:33:24,608: WARNING/ForkPoolWorker-3] Task B: 1

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

None

Possible Duplicates

None

Environment & Settings

Celery version: 5.05 and master (2411504)

celery report Output:

software -> celery:5.1.0b2 (singularity) kombu:5.1.0b1 py:3.9.5
billiard:3.6.4.0 py-amqp:5.0.6
platform -> system:Darwin arch:64bit
kernel version:20.4.0 imp:CPython
loader -> celery.loaders.app.AppLoader
settings -> transport:amqp results:disabled

deprecated_settings: None

Steps to Reproduce

Required Dependencies

Minimal Python Version: Unknown, tested on 3.9

Minimal Celery Version: Unknown, tested on 5.05 and master

Minimal Kombu Version: N/A

Minimal Broker Version: N/A

Minimal Result Backend Version: N/A

Minimal OS and/or Kernel Version: N/A

Minimal Broker Client Version: N/A

Minimal Result Backend Client Version: N/A

Python Packages

pip freeze Output:

amqp==5.0.6
billiard==3.6.4.0
celery @ git+https://github.com/celery/celery.git@2411504f4164ac9acfa20007038d37591c6f57e5
click==7.1.2
click-didyoumean==0.0.3
click-plugins==1.1.1
click-repl==0.1.6
kombu==5.1.0b1
prompt-toolkit==3.0.18
pytz==2021.1
six==1.16.0
vine==5.0.0
wcwidth==0.2.5

Other Dependencies

N/A

Minimally Reproducible Test Case

app.py:

import celery

app = celery.Celery()

camera.py:

from celery.events.snapshot import Polaroid

class Camera(Polaroid):
def on_shutter(self, _):
print("Hello!")

Expected Behavior

The following command should (attempt to) start the event camera:

$ celery -A app events -c camera
...
ModuleNotFoundError: No module named 'camera'

(The bug is independent of whether the module camera exists.)

Actual Behavior

A backtrace is produced:

Traceback (most recent call last):
File "/Users/user/Desktop/tmp/venv/bin/celery", line 8, in <module>
sys.exit(main())
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/celery/__main__.py", line 15, in main
sys.exit(_main())
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/celery/bin/celery.py", line 213, in main
return celery(auto_envvar_prefix="CELERY")
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/click/core.py", line 829, in __call__
return self.main(*args, **kwargs)
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/click/core.py", line 782, in main
rv = self.invoke(ctx)
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/click/core.py", line 1259, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/click/core.py", line 1066, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/click/core.py", line 610, in invoke
return callback(*args, **kwargs)
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/click/decorators.py", line 21, in new_func
return f(get_current_context(), *args, **kwargs)
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/celery/bin/base.py", line 132, in caller
return f(ctx, *args, **kwargs)
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/celery/bin/events.py", line 90, in events
return _run_evcam(camera, app=app, freq=frequency, maxrate=maxrate,
File "/Users/user/Desktop/tmp/venv/lib/python3.9/site-packages/celery/bin/events.py", line 37, in _run_evcam
return cam()
TypeError: evcam() got an unexpected keyword argument 'executable'