Checklist

• I have verified that the issue exists against the master branch of Celery. 90fe53f

• 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:

software -> celery:4.4.0 (cliffs) kombu:4.6.7 py:3.7.6
            billiard:3.6.1.0 redis:3.3.11
platform -> system:Linux arch:64bit
            kernel version:5.4.13-3-MANJARO imp:CPython
loader   -> celery.loaders.app.AppLoader
settings -> transport:redis results:redis://redis:6379/2

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

amqp==2.5.2
apipkg==1.5
attrs==19.3.0
backcall==0.1.0
billiard==3.6.1.0
blinker==1.4
boltons==19.3.0
cachetools==4.0.0
celery==4.4.0
certifi==2019.11.28
cffi==1.13.2
chardet==3.0.4
Click==7.0
cryptography==2.8
decorator==4.4.1
defusedxml==0.6.0
dnspython==1.16.0
dotted==0.1.8
elasticsearch==7.1.0
elasticsearch-dsl==7.1.0
execnet==1.7.1
Flask==1.1.1
Flask-Caching==1.4.0
Flask-Cors==3.0.8
Flask-Limiter==1.1.0
Flask-Login==0.4.1
flask-mongoengine==0.9.5
flask-shell-ipython==0.4.1
Flask-WTF==0.14.2
gevent==1.4.0
google-api-core==1.15.0
google-auth==1.10.0
google-cloud-core==1.1.0
google-cloud-pubsub==1.1.0
google-cloud-storage==1.23.0
google-resumable-media==0.5.0
googleapis-common-protos==1.6.0
greenlet==0.4.15
grpc-google-iam-v1==0.12.3
grpcio==1.26.0
httpagentparser==1.9.0
httplib2==0.15.0
idna==2.8
importlib-metadata==1.4.0
ipython==7.10.2
ipython-genutils==0.2.0
itsdangerous==1.1.0
jedi==0.15.2
Jinja2==2.10.3
kombu==4.6.7
libthumbor==1.3.2
limits==1.3
MarkupSafe==1.1.1
marshmallow==3.3.0
mixpanel==4.5.0
mmh3==2.5.1
mongoengine==0.18.2
more-itertools==8.1.0
multidict==4.7.4
ndg-httpsclient==0.5.1
newrelic==5.4.1.134
nexmo==2.4.0
oauth2client==4.1.3
oauthlib==3.1.0
packaging==20.0
parso==0.5.2
pexpect==4.7.0
phonenumbers==8.11.1
pickleshare==0.7.5
Pillow-SIMD==6.0.0.post0
pluggy==0.13.1
prompt-toolkit==3.0.2
protobuf==3.9.0
ptyprocess==0.6.0
pusher==2.1.4
py==1.8.1
py-cpuinfo==5.0.0
pyasn1==0.4.8
pyasn1-modules==0.2.8
pybase62==0.4.3
pycparser==2.19
Pygments==2.5.2
PyJWT==1.7.1
pymongo==3.10.0
PyNaCl==1.3.0
pyOpenSSL==19.1.0
pyparsing==2.4.6
pytelegraf==0.3.3
pytest==5.3.2
pytest-benchmark==3.2.3
pytest-forked==1.1.3
pytest-mock==1.13.0
pytest-sugar==0.9.2
pytest-xdist==1.31.0
python-dateutil==2.8.1
python-rapidjson==0.9.1
python3-openid==3.1.0
pytz==2019.3
PyYAML==5.2
redis==3.3.11
requests==2.22.0
requests-oauthlib==1.3.0
rsa==4.0
semantic-version==2.8.3
sentry-sdk==0.13.5
six==1.13.0
social-auth-app-flask==1.0.0
social-auth-core==3.2.0
social-auth-storage-mongoengine==1.0.1
termcolor==1.1.0
traitlets==4.3.3
twilio==6.35.1
urllib3==1.25.7
uWSGI==2.0.18
vine==1.3.0
wcwidth==0.1.8
webargs==5.5.2
Werkzeug==0.15.5
WTForms==2.2.1
yarl==1.4.2
zipp==0.6.0

Other Dependencies

Minimally Reproducible Test Case

import time
from flask import Flask
from celery import Celery, group


app = Flask(__name__)
celery = Celery('app', broker='redis://redis:6379/1', backend='redis://redis:6379/2')


@celery.task
def debug():
    return


@app.route('/', methods={'GET', 'POST'})
def hello_world():
    task = group([
        debug.si() for i in range(10)
    ]).apply_async()

    start = time.perf_counter()
    task.get(timeout=5, interval=0.01)
    print('END', (time.perf_counter() - start) * 1000)
    return {}

Expected Behavior

Scheduling noop tasks and setting interval should make the response time near the set interval in ideal clean environments.

Example: Setting task.get(interval=0.1) with 5x noop tasks, I would expect near 100ms response.

Actual Behavior

Regardless of the setting of interval, the response time is at least 500ms.

The cause is that interval is not passed all the way to get_many() where it defaults to 500ms which is where the minimum latency is comming from.