<h1 dir="auto">Checklist</h1>

<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have verified that the issue exists against the <code class="notranslate">master</code> branch of Celery.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> This has already been asked to the <a href="https://github.com/celery/celery/discussions">discussions forum</a> first.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have read the relevant section in the<br>
<a href="http://docs.celeryproject.org/en/latest/contributing.html#other-bugs" rel="nofollow">contribution guide</a><br>
on reporting bugs.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/issues?q=is%3Aissue+label%3A%22Issue+Type%3A+Bug+Report%22+-label%3A%22Category%3A+Documentation%22">issues list</a><br>
for similar or identical bug reports.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/pulls?q=is%3Apr+label%3A%22PR+Type%3A+Bugfix%22+-label%3A%22Category%3A+Documentation%22">pull requests list</a><br>
for existing proposed fixes.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/commits/master">commit log</a><br>
to find out if the bug was already fixed in the master branch.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have included all related issues and possible duplicate issues<br>
in this issue (If there are none, check this box anyway).</li>
</ul>
<h2 dir="auto">Mandatory Debugging Information</h2>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have included the output of <code class="notranslate">celery -A proj report</code> in the issue.<br>
(if you are not able to do this, then at least specify the Celery<br>
version affected).</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have verified that the issue exists against the <code class="notranslate">master</code> branch of Celery.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have included the contents of <code class="notranslate">pip freeze</code> in the issue.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have included all the versions of all the external dependencies required<br>
to reproduce this bug.</li>
</ul>
<h2 dir="auto">Optional Debugging Information</h2>

<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one Python version<br>
and/or implementation.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one message broker and/or<br>
result backend.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one version of the message<br>
broker and/or result backend.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one operating system.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one workers pool.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue with autoscaling, retries,<br>
ETA/Countdown &amp; rate limits disabled.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue after downgrading<br>
and/or upgrading Celery and its dependencies.</li>
</ul>
<h2 dir="auto">Related Issues and Possible Duplicates</h2>

<h4 dir="auto">Related Issues</h4>
<ul dir="auto">
<li>None</li>
</ul>
<h4 dir="auto">Possible Duplicates</h4>
<ul dir="auto">
<li>None</li>
</ul>
<h2 dir="auto">Environment &amp; Settings</h2>

<p dir="auto"><strong>Celery version</strong>: 5.2.1 (dawn-chorus)</p>

<details>
<summary><b><code class="notranslate">celery report</code> Output:</b></summary>
<p dir="auto">
</p><p dir="auto">Output from celery report</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="software -&gt; celery:5.2.1 (dawn-chorus) kombu:5.2.2 py:3.7.4
            billiard:3.6.4.0 py-amqp:5.0.9
platform -&gt; system:Darwin arch:64bit
            kernel version:20.5.0 imp:CPython
loader   -&gt; celery.loaders.default.Loader
settings -&gt; transport:amqp results:disabled

deprecated_settings: None"><pre class="notranslate"><code class="notranslate">software -&gt; celery:5.2.1 (dawn-chorus) kombu:5.2.2 py:3.7.4
            billiard:3.6.4.0 py-amqp:5.0.9
platform -&gt; system:Darwin arch:64bit
            kernel version:20.5.0 imp:CPython
loader   -&gt; celery.loaders.default.Loader
settings -&gt; transport:amqp results:disabled

deprecated_settings: None
</code></pre></div>
<p dir="auto"></p>
</details>
<h1 dir="auto">Steps to Reproduce</h1>
<h2 dir="auto">Required Dependencies</h2>

<ul dir="auto">
<li><strong>Minimal Python Version</strong>: I've been testing under multiple virtual environments of python: 3.7.4, 3.8.5, 3.9.6</li>
<li><strong>Minimal Celery Version</strong>: master</li>
<li><strong>Minimal Kombu Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Broker Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Result Backend Version</strong>: N/A or Unknown</li>
<li><strong>Minimal OS and/or Kernel Version</strong>: MacOS Big Sur 11.4</li>
<li><strong>Minimal Broker Client Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Result Backend Client Version</strong>: N/A or Unknown</li>
</ul>
<h3 dir="auto">Python Packages</h3>

<details>
<summary><b><code class="notranslate">pip freeze</code> Output:</b></summary>
<p dir="auto">
</p><div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="(3.7.4/envs/stellar_3_7) pinchas.lev@Pinchass-MacBook-Pro celery % pip3 freeze
amqp==5.0.9
appdirs==1.4.4
asgiref==3.4.1
astroid==2.6.6
attrs==21.2.0
autopep8==1.5.7
Babel==2.9.1
backports.entry-points-selectable==1.1.1
bcrypt==3.2.0
beautifulsoup4==4.10.0
before-after==1.0.1
billiard==3.6.4.0
black==21.7b0
bleach==4.1.0
boto3==1.20.26
botocore==1.23.26
cached-property==1.5.2
cachetools==4.2.4
cairocffi==1.1.0
CairoSVG==2.5.2
cchardet==2.1.7
celery==5.2.1
celery-once==3.0.1
certifi==2021.5.30
cffi==1.14.6
cfgv==3.3.1
chardet==3.0.4
charset-normalizer==2.0.7
click==8.0.3
click-didyoumean==0.3.0
click-plugins==1.1.1
click-repl==0.2.0
colorama==0.4.3
cryptography==3.4.8
cssselect2==0.4.1
customerio==1.0
Cython==0.29.22
defusedxml==0.7.1
distlib==0.3.4
dj-database-url==0.5.0
Django==3.2.9
django-add-default-value==0.9.1
django-admin-autocomplete-filter==0.6.1
django-appconf==1.0.4
django-axes==5.2.2
django-better-admin-arrayfield==1.4.2
django-ckeditor==5.8.0
django-compressor==2.4.1
django-cryptography==1.0
django-csp==3.7
django-debug-toolbar==3.1.1
django-dirtyfields==1.7.0
django-guardian==2.4.0
django-ipware==2.1.0
django-js-asset==1.2.2
django-libsass==0.9
django-migration-linter==2.5.3
django-pglocks==1.0.4
django-polymorphic==3.0.0
django-redis==5.0.0
django-silk==4.1.0
django-storages==1.8
django-termsandconditions==2.0.9
django-user-sessions==1.7.1
django-webpack-loader==1.4.1
django-widget-tweaks==1.4.9
djangorestframework==3.11.0
djangorestframework-datatables==0.5.1
dnspython==1.16.0
docutils==0.15.2
dparse==0.5.1
elasticsearch==7.12.1
et-xmlfile==1.1.0
eventlet==0.30.2
expiringdict==1.2.1
filelock==3.4.0
flower==0.9.3
freezegun==0.3.13
future==0.18.2
fuzzywuzzy==0.18.0
geoip2==2.9.0
gevent==1.4.0
gprof2dot==2021.2.21
greenlet==1.1.0
gunicorn==20.1.0
html5lib==1.1
identify==2.4.0
idna==2.8
importlib-metadata==4.6.1
influxdb==5.2.3
iniconfig==1.1.1
isodate==0.6.0
isort==5.9.3
jdcal==1.4.1
Jinja2==3.0.1
jmespath==0.9.4
kombu==5.2.2
lazy-object-proxy==1.6.0
libsass==0.21.0
lxml==4.6.3
MarkupSafe==2.0.1
marshmallow==2.20.5
maxminddb==2.0.3
mccabe==0.6.1
mock==1.0.1
more-itertools==8.10.0
moto==2.2.19
msgpack==1.0.3
mypy-extensions==0.4.3
newrelic==7.2.4.171
nodeenv==1.6.0
numpy==1.19.5
openpyxl==3.0.3
packaging==21.0
pandas==0.25.3
paramiko==2.8.0
pathspec==0.9.0
pep8==1.7.1
phonenumbers==8.12.36
Pillow==8.3.1
platformdirs==2.4.0
pluggy==1.0.0
pre-commit==2.16.0
prompt-toolkit==3.0.24
psutil==5.8.0
psycopg2-binary==2.8.6
py==1.11.0
pycodestyle==2.5.0
pycparser==2.20
pyflakes==2.3.1
Pygments==2.9.0
pylint==2.9.6
pymongo==4.0.1
PyNaCl==1.4.0
pyparsing==2.4.7
pyphen==0.11.0
pysftp==0.2.9
pytest==6.2.5
pytest-celery==0.0.0
pytest-subtests==0.5.0
pytest-timeout==1.4.2
python-crontab==2.5.1
python-dateutil==2.8.2
python-Levenshtein==0.12.2
python3-saml==1.9.0
pytz==2021.3
pyx12==2.3.3
PyYAML==6.0
rcssmin==1.0.6
redis==3.5.3
regex==2021.8.3
requests==2.26.0
responses==0.16.0
rjsmin==1.1.0
s3transfer==0.5.0
safety==1.8.5
si-prefix==1.2.2
simplejson==3.17.5
six==1.16.0
sodapy==2.0.0
soupsieve==2.2.1
sqlparse==0.4.1
structlog==19.2.0
tblib==1.7.0
tenacity==6.2.0
tinycss2==1.0.2
toml==0.10.2
tomli==1.2.1
tornado==5.1.1
typed-ast==1.4.3
typing==3.7.4.3
typing-extensions==3.10.0.0
urllib3==1.25.7
vine==5.0.0
virtualenv==20.10.0
wcwidth==0.2.5
WeasyPrint==52.5
webencodings==0.5.1
Werkzeug==2.0.2
whitenoise==5.3.0
wrapt==1.12.1
xlrd==1.2.0
xmlsec==1.3.11
xmltodict==0.12.0
zipp==3.5.0"><pre class="notranslate"><code class="notranslate">(3.7.4/envs/stellar_3_7) pinchas.lev@Pinchass-MacBook-Pro celery % pip3 freeze
amqp==5.0.9
appdirs==1.4.4
asgiref==3.4.1
astroid==2.6.6
attrs==21.2.0
autopep8==1.5.7
Babel==2.9.1
backports.entry-points-selectable==1.1.1
bcrypt==3.2.0
beautifulsoup4==4.10.0
before-after==1.0.1
billiard==3.6.4.0
black==21.7b0
bleach==4.1.0
boto3==1.20.26
botocore==1.23.26
cached-property==1.5.2
cachetools==4.2.4
cairocffi==1.1.0
CairoSVG==2.5.2
cchardet==2.1.7
celery==5.2.1
celery-once==3.0.1
certifi==2021.5.30
cffi==1.14.6
cfgv==3.3.1
chardet==3.0.4
charset-normalizer==2.0.7
click==8.0.3
click-didyoumean==0.3.0
click-plugins==1.1.1
click-repl==0.2.0
colorama==0.4.3
cryptography==3.4.8
cssselect2==0.4.1
customerio==1.0
Cython==0.29.22
defusedxml==0.7.1
distlib==0.3.4
dj-database-url==0.5.0
Django==3.2.9
django-add-default-value==0.9.1
django-admin-autocomplete-filter==0.6.1
django-appconf==1.0.4
django-axes==5.2.2
django-better-admin-arrayfield==1.4.2
django-ckeditor==5.8.0
django-compressor==2.4.1
django-cryptography==1.0
django-csp==3.7
django-debug-toolbar==3.1.1
django-dirtyfields==1.7.0
django-guardian==2.4.0
django-ipware==2.1.0
django-js-asset==1.2.2
django-libsass==0.9
django-migration-linter==2.5.3
django-pglocks==1.0.4
django-polymorphic==3.0.0
django-redis==5.0.0
django-silk==4.1.0
django-storages==1.8
django-termsandconditions==2.0.9
django-user-sessions==1.7.1
django-webpack-loader==1.4.1
django-widget-tweaks==1.4.9
djangorestframework==3.11.0
djangorestframework-datatables==0.5.1
dnspython==1.16.0
docutils==0.15.2
dparse==0.5.1
elasticsearch==7.12.1
et-xmlfile==1.1.0
eventlet==0.30.2
expiringdict==1.2.1
filelock==3.4.0
flower==0.9.3
freezegun==0.3.13
future==0.18.2
fuzzywuzzy==0.18.0
geoip2==2.9.0
gevent==1.4.0
gprof2dot==2021.2.21
greenlet==1.1.0
gunicorn==20.1.0
html5lib==1.1
identify==2.4.0
idna==2.8
importlib-metadata==4.6.1
influxdb==5.2.3
iniconfig==1.1.1
isodate==0.6.0
isort==5.9.3
jdcal==1.4.1
Jinja2==3.0.1
jmespath==0.9.4
kombu==5.2.2
lazy-object-proxy==1.6.0
libsass==0.21.0
lxml==4.6.3
MarkupSafe==2.0.1
marshmallow==2.20.5
maxminddb==2.0.3
mccabe==0.6.1
mock==1.0.1
more-itertools==8.10.0
moto==2.2.19
msgpack==1.0.3
mypy-extensions==0.4.3
newrelic==7.2.4.171
nodeenv==1.6.0
numpy==1.19.5
openpyxl==3.0.3
packaging==21.0
pandas==0.25.3
paramiko==2.8.0
pathspec==0.9.0
pep8==1.7.1
phonenumbers==8.12.36
Pillow==8.3.1
platformdirs==2.4.0
pluggy==1.0.0
pre-commit==2.16.0
prompt-toolkit==3.0.24
psutil==5.8.0
psycopg2-binary==2.8.6
py==1.11.0
pycodestyle==2.5.0
pycparser==2.20
pyflakes==2.3.1
Pygments==2.9.0
pylint==2.9.6
pymongo==4.0.1
PyNaCl==1.4.0
pyparsing==2.4.7
pyphen==0.11.0
pysftp==0.2.9
pytest==6.2.5
pytest-celery==0.0.0
pytest-subtests==0.5.0
pytest-timeout==1.4.2
python-crontab==2.5.1
python-dateutil==2.8.2
python-Levenshtein==0.12.2
python3-saml==1.9.0
pytz==2021.3
pyx12==2.3.3
PyYAML==6.0
rcssmin==1.0.6
redis==3.5.3
regex==2021.8.3
requests==2.26.0
responses==0.16.0
rjsmin==1.1.0
s3transfer==0.5.0
safety==1.8.5
si-prefix==1.2.2
simplejson==3.17.5
six==1.16.0
sodapy==2.0.0
soupsieve==2.2.1
sqlparse==0.4.1
structlog==19.2.0
tblib==1.7.0
tenacity==6.2.0
tinycss2==1.0.2
toml==0.10.2
tomli==1.2.1
tornado==5.1.1
typed-ast==1.4.3
typing==3.7.4.3
typing-extensions==3.10.0.0
urllib3==1.25.7
vine==5.0.0
virtualenv==20.10.0
wcwidth==0.2.5
WeasyPrint==52.5
webencodings==0.5.1
Werkzeug==2.0.2
whitenoise==5.3.0
wrapt==1.12.1
xlrd==1.2.0
xmlsec==1.3.11
xmltodict==0.12.0
zipp==3.5.0
</code></pre></div>
<p dir="auto"></p>
</details>
<h3 dir="auto">Other Dependencies</h3>

<details>
<p dir="auto">
N/A
</p>
</details>
<h2 dir="auto">Minimally Reproducible Test Case</h2>

<details>
<p dir="auto">
</p><div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="pytest t/unit"><pre class="notranslate"><code class="notranslate">pytest t/unit
</code></pre></div>
<p dir="auto"></p>
</details>
<h1 dir="auto">Expected Behavior</h1>

<p dir="auto">I expected all tests to pass</p>
<h1 dir="auto">Actual Behavior</h1>
<h1 dir="auto">Checklist</h1>

<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have verified that the issue exists against the <code class="notranslate">master</code> branch of Celery.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> This has already been asked to the <a href="https://groups.google.com/forum/#!forum/celery-users" rel="nofollow">discussion group</a> first.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have read the relevant section in the<br>
<a href="http://docs.celeryproject.org/en/latest/contributing.html#other-bugs" rel="nofollow">contribution guide</a><br>
on reporting bugs.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/issues?q=is%3Aissue+label%3A%22Issue+Type%3A+Bug+Report%22+-label%3A%22Category%3A+Documentation%22">issues list</a><br>
for similar or identical bug reports.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the <a href="https://github.com/celery/celery/pulls?q=is%3Apr+label%3A%22PR+Type%3A+Bugfix%22+-label%3A%22Category%3A+Documentation%22">pull requests list</a><br>
for existing proposed fixes.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have checked the <a href="https://github.com/celery/celery/commits/master">commit log</a><br>
to find out if the bug was already fixed in the master branch.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have included all related issues and possible duplicate issues<br>
in this issue (If there are none, check this box anyway).</li>
</ul>
<h2 dir="auto">Mandatory Debugging Information</h2>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have included the output of <code class="notranslate">celery -A proj report</code> in the issue.<br>
(if you are not able to do this, then at least specify the Celery<br>
version affected).</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have verified that the issue exists against the <code class="notranslate">master</code> branch of Celery.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have included the contents of <code class="notranslate">pip freeze</code> in the issue.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have included all the versions of all the external dependencies required<br>
to reproduce this bug.</li>
</ul>
<h2 dir="auto">Optional Debugging Information</h2>

<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one Python version<br>
and/or implementation.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one message broker and/or<br>
result backend.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue on more than one version of the message<br>
broker and/or result backend.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have tried reproducing the issue on more than one operating system.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have tried reproducing the issue on more than one workers pool.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue with autoscaling, retries,<br>
ETA/Countdown &amp; rate limits disabled.</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have tried reproducing the issue after downgrading<br>
and/or upgrading Celery and its dependencies.</li>
</ul>
<h2 dir="auto">Related Issues and Possible Duplicates</h2>

<h4 dir="auto">Related Issues</h4>
<ul dir="auto">
<li>None</li>
</ul>
<h4 dir="auto">Possible Duplicates</h4>
<ul dir="auto">
<li>None</li>
</ul>
<h2 dir="auto">Environment &amp; Settings</h2>

<p dir="auto"><strong>Celery version</strong>: 4.4.0 (cliffs)</p>

<details>
<summary><b><code class="notranslate">celery report</code> Output:</b></summary>
<p dir="auto">
</p><div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="
software -&gt; celery:4.4.0 (cliffs) kombu:4.6.7 py:3.8.1
            billiard:3.6.1.0 redis:3.3.11
platform -&gt; system:Darwin arch:64bit
            kernel version:18.7.0 imp:CPython
loader   -&gt; celery.loaders.app.AppLoader
settings -&gt; transport:redis results:disabled

BROKER_URL: 'redis://localhost:6379/1'
CELERYD_PREFETCH_MULTIPLIER: 1
CELERY_ACCEPT_CONTENT: ['json']
CELERY_RESULT_SERIALIZER: 'json'
CELERY_TASK_ACKS_LATE: True
CELERY_TASK_RESULT_EXPIRES: 86400
CELERY_TASK_SERIALIZER: 'json'
CELERY_TIMEZONE: 'Asia/Chongqing'
CELERY_INCLUDE: ['proj.tasks']"><pre class="notranslate"><code class="notranslate">
software -&gt; celery:4.4.0 (cliffs) kombu:4.6.7 py:3.8.1
            billiard:3.6.1.0 redis:3.3.11
platform -&gt; system:Darwin arch:64bit
            kernel version:18.7.0 imp:CPython
loader   -&gt; celery.loaders.app.AppLoader
settings -&gt; transport:redis results:disabled

BROKER_URL: 'redis://localhost:6379/1'
CELERYD_PREFETCH_MULTIPLIER: 1
CELERY_ACCEPT_CONTENT: ['json']
CELERY_RESULT_SERIALIZER: 'json'
CELERY_TASK_ACKS_LATE: True
CELERY_TASK_RESULT_EXPIRES: 86400
CELERY_TASK_SERIALIZER: 'json'
CELERY_TIMEZONE: 'Asia/Chongqing'
CELERY_INCLUDE: ['proj.tasks']
</code></pre></div>
<p dir="auto"></p>
</details>
<h1 dir="auto">Steps to Reproduce</h1>
<h2 dir="auto">Required Dependencies</h2>

<ul dir="auto">
<li><strong>Minimal Python Version</strong>: 3.8.1</li>
<li><strong>Minimal Celery Version</strong>: 4.4.0</li>
<li><strong>Minimal Kombu Version</strong>: 4.6.7</li>
<li><strong>Minimal Broker Version</strong>: redis_version:4.0.10</li>
<li><strong>Minimal Result Backend Version</strong>: N/A or Unknown</li>
<li><strong>Minimal OS and/or Kernel Version</strong>: Mac; Centos</li>
<li><strong>Minimal Broker Client Version</strong>: redis 3.3.11</li>
<li><strong>Minimal Result Backend Client Version</strong>: N/A or Unknown</li>
</ul>
<h3 dir="auto">Python Packages</h3>

<details>
<summary><b><code class="notranslate">pip freeze</code> Output:</b></summary>
<p dir="auto">
</p><div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="amqp==2.5.2
billiard==3.6.1.0
celery==4.4.0
gevent==1.4.0
greenlet==0.4.15
kombu==4.6.7
pytz==2019.3
redis==3.3.11
vine==1.3.0"><pre class="notranslate"><code class="notranslate">amqp==2.5.2
billiard==3.6.1.0
celery==4.4.0
gevent==1.4.0
greenlet==0.4.15
kombu==4.6.7
pytz==2019.3
redis==3.3.11
vine==1.3.0
</code></pre></div>
<p dir="auto"></p>
</details>
<h3 dir="auto">Other Dependencies</h3>

<details>
<p dir="auto">
N/A
</p>
</details>
<h2 dir="auto">Minimally Reproducible Test Case</h2>

<details>
<p dir="auto">
</p><div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content=""><pre class="notranslate"></pre></div>
<p dir="auto"></p>
</details>
<h1 dir="auto">Expected Behavior</h1>

<p dir="auto">I have many task with countdown in celery, I hope the worker can prefetch the task one by one. But worker will almost prefetch all of the tasks. This is my worker start cmd:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="celery -A proj.celery.app  worker -l info -c 1"><pre class="notranslate"><code class="notranslate">celery -A proj.celery.app  worker -l info -c 1
</code></pre></div>
<p dir="auto">It will prefetch all of the tasks.<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/17327054/72675382-da110580-3abd-11ea-96bb-8c45ff3af568.png"><img src="https://user-images.githubusercontent.com/17327054/72675382-da110580-3abd-11ea-96bb-8c45ff3af568.png" alt="image" style="max-width: 100%;"></a></p>
<h1 dir="auto">Actual Behavior</h1>