<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" checked=""> 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"> 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" checked=""> 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">4.4.7 (cliffs)<br>
<strong>Celery version</strong>:</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:4.4.7 (cliffs) kombu:4.6.11 py:3.6.12
            billiard:3.6.3.0 redis:3.5.3
platform -&gt; system:Linux arch:64bit
            kernel version:4.4.0-1098-aws imp:CPython
loader   -&gt; celery.loaders.app.AppLoader
settings -&gt; transport:redis results:disabled"><pre class="notranslate"><code class="notranslate">software -&gt; celery:4.4.7 (cliffs) kombu:4.6.11 py:3.6.12
            billiard:3.6.3.0 redis:3.5.3
platform -&gt; system:Linux arch:64bit
            kernel version:4.4.0-1098-aws imp:CPython
loader   -&gt; celery.loaders.app.AppLoader
settings -&gt; transport:redis results:disabled
</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>: N/A or Unknown</li>
<li><strong>Minimal Celery Version</strong>: 4.0.0</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>: N/A or Unknown</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="amqp==2.6.1
anyjson==0.3.3
apns2==0.3.0
appdirs==1.4.4
args==0.1.0
asn1crypto==1.4.0
attrs==21.4.0
backports.shutil-get-terminal-size==1.0.0
beautifulsoup4==4.6.0
billiard==3.6.3.0
boto==2.48.0
cached-property==1.5.2
cairocffi==1.1.0
CairoSVG==2.4.0
celery==4.4.7
certifi==2018.1.18
cffi==1.14.3
chardet==3.0.4
clint==0.5.1
cryptography==2.9.2
cssselect==1.0.0
cssselect2==0.2.2
cssutils==1.0.2
decorator==4.2.1
defusedxml==0.6.0
diff-match-patch==20121119
Django==1.11.11
django-admin-bootstrapped-rubgomez93==3.0.1
django-ajax-selects==1.7.0
django-bootstrap3-datetimepicker-rubgomez93==3.0.2
django-boto==0.3.12
django-constance==2.1.0
django-cookies-samesite==0.5.1
django-cors-headers==2.2.0
django-countries==5.5
django-dbconn-retry==0.1.5
django-debug-toolbar==1.9.1
django-filter==1.1.0
django-form-admin==0.5.1
django-import-export==1.0.0
django-localflavor==2.0
django-money==0.12.3
django-multiselectfield==0.1.8
django-p3p==1.2.0
django-picklefield==1.0.0
django-proxy==1.1.0
django-push-notifications-rubgomez93==1.6.4
django-redis==4.11.0
django-session-timeout-joinup==1.0.0
django-storages==1.6.5
django-su==0.6.0
django-tables2==2.3.1
django-timezone-field==2.1
djangorestframework==3.6.4
djangorestframework-gis==0.11.2
djangorestframework-jwt==1.11.0
djangorestframework-xml==1.3.0
ecdsa==0.13
eight==0.4.2
endesive==1.5.12
enum34==1.1.6
et-xmlfile==1.0.1
forex-python==1.3
funcsigs==1.0.2
future==0.16.0
geopy==1.11.0
google-api-python-client==1.6.5
gunicorn==19.7.1
h2==2.6.2
hpack==3.0.0
html5lib==1.0.1
http-ece==1.0.5
httplib2==0.18.1
hyper==0.7.0
hyperframe==3.2.0
idna==2.6
importlib-metadata==4.8.3
importlib-resources==5.4.0
ipaddress==1.0.19
ipython-genutils==0.2.0
iso3166==2.0.2
isodate==0.6.1
jdcal==1.3
jsonfield-joinup==2.1.2
kombu==4.6.11
lxml==4.1.1
mock==2.0.0
numpy==1.19.5
oauth2client==4.1.2
odfpy==1.3.6
olefile==0.45.1
openpyxl==2.4.9
oscrypto==1.2.1
paramiko==2.1.1
pathlib2==2.3.0
pbr==3.1.1
pdfrw==0.4
pexpect==4.4.0
PGPy==0.5.3
phonenumbers==8.9.0
pickleshare==0.7.4
Pillow==4.1.1
polyline==1.4.0
prompt-toolkit==2.0.10
psutil==5.6.1
psycopg2==2.7.4
psycopg2-binary==2.7.4
ptyprocess==0.5.2
py-moneyed==0.7.0
py-vapid==1.3.0
pyasn1==0.4.2
pyasn1-modules==0.2.1
pycairo==1.16.3
pycparser==2.20
Pygments==2.2.0
PyJWT==1.6.0
PyKCS11==1.5.9
pymongo==3.10.1
pynliner==0.8.0
pyOpenSSL==17.5.0
Pyphen==0.9.4
pysftp==0.2.9
PySocks==1.7.1
python-dateutil==2.6.1
pytz==2018.3
pywebpush==1.6.0
PyYAML==3.12
redis==3.5.3
requests==2.22.0
requests-toolbelt==0.9.1
rsa==3.4.2
scandir==1.7
schwifty==2020.2.2
signxml==2.5.2
simplegeneric==0.8.1
simplejson==3.16.0
six==1.15.0
smsutil==1.1.3
sqlparse==0.2.4
static3==0.7.0
stripe==2.32.1
tablib==0.12.1
timezonefinder==3.4.2
tinycss==0.4
tinycss2==1.0.0
traitlets==4.3.2
typing-extensions==4.0.1
unicodecsv==0.14.1
uritemplate==3.0.0
urllib3==1.22
vine==1.3.0
wcwidth==0.1.7
WeasyPrint==51
webencodings==0.5.1
whitenoise==3.3.1
xlrd==1.1.0
XlsxWriter==1.0.2
xlwt==1.3.0
zeep==3.4.0
zipp==3.6.0"><pre class="notranslate"><code class="notranslate">amqp==2.6.1
anyjson==0.3.3
apns2==0.3.0
appdirs==1.4.4
args==0.1.0
asn1crypto==1.4.0
attrs==21.4.0
backports.shutil-get-terminal-size==1.0.0
beautifulsoup4==4.6.0
billiard==3.6.3.0
boto==2.48.0
cached-property==1.5.2
cairocffi==1.1.0
CairoSVG==2.4.0
celery==4.4.7
certifi==2018.1.18
cffi==1.14.3
chardet==3.0.4
clint==0.5.1
cryptography==2.9.2
cssselect==1.0.0
cssselect2==0.2.2
cssutils==1.0.2
decorator==4.2.1
defusedxml==0.6.0
diff-match-patch==20121119
Django==1.11.11
django-admin-bootstrapped-rubgomez93==3.0.1
django-ajax-selects==1.7.0
django-bootstrap3-datetimepicker-rubgomez93==3.0.2
django-boto==0.3.12
django-constance==2.1.0
django-cookies-samesite==0.5.1
django-cors-headers==2.2.0
django-countries==5.5
django-dbconn-retry==0.1.5
django-debug-toolbar==1.9.1
django-filter==1.1.0
django-form-admin==0.5.1
django-import-export==1.0.0
django-localflavor==2.0
django-money==0.12.3
django-multiselectfield==0.1.8
django-p3p==1.2.0
django-picklefield==1.0.0
django-proxy==1.1.0
django-push-notifications-rubgomez93==1.6.4
django-redis==4.11.0
django-session-timeout-joinup==1.0.0
django-storages==1.6.5
django-su==0.6.0
django-tables2==2.3.1
django-timezone-field==2.1
djangorestframework==3.6.4
djangorestframework-gis==0.11.2
djangorestframework-jwt==1.11.0
djangorestframework-xml==1.3.0
ecdsa==0.13
eight==0.4.2
endesive==1.5.12
enum34==1.1.6
et-xmlfile==1.0.1
forex-python==1.3
funcsigs==1.0.2
future==0.16.0
geopy==1.11.0
google-api-python-client==1.6.5
gunicorn==19.7.1
h2==2.6.2
hpack==3.0.0
html5lib==1.0.1
http-ece==1.0.5
httplib2==0.18.1
hyper==0.7.0
hyperframe==3.2.0
idna==2.6
importlib-metadata==4.8.3
importlib-resources==5.4.0
ipaddress==1.0.19
ipython-genutils==0.2.0
iso3166==2.0.2
isodate==0.6.1
jdcal==1.3
jsonfield-joinup==2.1.2
kombu==4.6.11
lxml==4.1.1
mock==2.0.0
numpy==1.19.5
oauth2client==4.1.2
odfpy==1.3.6
olefile==0.45.1
openpyxl==2.4.9
oscrypto==1.2.1
paramiko==2.1.1
pathlib2==2.3.0
pbr==3.1.1
pdfrw==0.4
pexpect==4.4.0
PGPy==0.5.3
phonenumbers==8.9.0
pickleshare==0.7.4
Pillow==4.1.1
polyline==1.4.0
prompt-toolkit==2.0.10
psutil==5.6.1
psycopg2==2.7.4
psycopg2-binary==2.7.4
ptyprocess==0.5.2
py-moneyed==0.7.0
py-vapid==1.3.0
pyasn1==0.4.2
pyasn1-modules==0.2.1
pycairo==1.16.3
pycparser==2.20
Pygments==2.2.0
PyJWT==1.6.0
PyKCS11==1.5.9
pymongo==3.10.1
pynliner==0.8.0
pyOpenSSL==17.5.0
Pyphen==0.9.4
pysftp==0.2.9
PySocks==1.7.1
python-dateutil==2.6.1
pytz==2018.3
pywebpush==1.6.0
PyYAML==3.12
redis==3.5.3
requests==2.22.0
requests-toolbelt==0.9.1
rsa==3.4.2
scandir==1.7
schwifty==2020.2.2
signxml==2.5.2
simplegeneric==0.8.1
simplejson==3.16.0
six==1.15.0
smsutil==1.1.3
sqlparse==0.2.4
static3==0.7.0
stripe==2.32.1
tablib==0.12.1
timezonefinder==3.4.2
tinycss==0.4
tinycss2==1.0.0
traitlets==4.3.2
typing-extensions==4.0.1
unicodecsv==0.14.1
uritemplate==3.0.0
urllib3==1.22
vine==1.3.0
wcwidth==0.1.7
WeasyPrint==51
webencodings==0.5.1
whitenoise==3.3.1
xlrd==1.1.0
XlsxWriter==1.0.2
xlwt==1.3.0
zeep==3.4.0
zipp==3.6.0
</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>
<p dir="auto">I have added a unit test (<a href="https://github.com/we-are-Joinup/celery/commit/6d0c1327ec895543052ff32b51e34771d5843f74">test_pending_left_10_milliseconds_tick</a>) in my fork. This test fails with current master branch, but this does not fails with my forked master branch</p>
<h1 dir="auto">Expected Behavior</h1>
<p dir="auto">Celery beat executes tasks periodically and sleeps until the next task is dued. So we expect celery beat periodically executes the corresponding tasks without the process sleeping more than the necessary time between task executions.</p>
<p dir="auto">For our case:</p>
<ul dir="auto">
<li>The task that we scheduled with the lowest value is 13 seconds.</li>
<li>Celery beat should not sleep more than 13 seconds in any case.</li>
</ul>
<h1 dir="auto">Actual Behavior</h1>
<p dir="auto">Sometimes celery beat calculates wrong that the time to sleep is 300 seconds (default value for max interval). In our case, it pass kind of one time per day.</p>
<p dir="auto">How it is possible?:</p>
<ul dir="auto">
<li>If the next task to run will due in 0.01 seconds, so this tasks is not dued still, the tick function will calculate the time that celery beat process should sleep.</li>
<li>To calculate it, <a href="https://github.com/celery/celery/blob/v5.2.3/celery/beat.py#L328">tick</a> function calls to the function <a href="https://github.com/celery/celery/blob/v5.2.3/celery/beat.py#L294">adjust</a>, this subtracts 0.01 to next_time_to_run variable. The result of this operation is 0.</li>
<li>The return value of the tick function will be maximum between:
<ul dir="auto">
<li>0 or max interval =&gt; max interval</li>
<li>max interval</li>
</ul>
</li>
<li>So, celery beat will sleep wrongly for max interval (300 seconds)</li>
</ul>
<p dir="auto">I have added comments to these functions with the tag [ISSUE_COMMENT] to describe this case</p>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="def adjust(self, n, drift=-0.010):  
    if n and n &gt; 0:
        # [ISSUE_COMMENT] if n is 0.01 this function returns 0.01 + (-0.010) = 0.0
        return n + drift
    return n"><pre class="notranslate"><span class="pl-k">def</span> <span class="pl-en">adjust</span>(<span class="pl-s1">self</span>, <span class="pl-s1">n</span>, <span class="pl-s1">drift</span><span class="pl-c1">=</span><span class="pl-c1">-</span><span class="pl-c1">0.010</span>):  
    <span class="pl-k">if</span> <span class="pl-s1">n</span> <span class="pl-c1">and</span> <span class="pl-s1">n</span> <span class="pl-c1">&gt;</span> <span class="pl-c1">0</span>:
        <span class="pl-c"># [ISSUE_COMMENT] if n is 0.01 this function returns 0.01 + (-0.010) = 0.0</span>
        <span class="pl-k">return</span> <span class="pl-s1">n</span> <span class="pl-c1">+</span> <span class="pl-s1">drift</span>
    <span class="pl-k">return</span> <span class="pl-s1">n</span></pre></div>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="def tick(self, event_t=event_t, min=min,
         heappop=heapq.heappop, heappush=heapq.heappush,
         heapify=heapq.heapify, mktime=time.mktime):

    ...

    event = H[0]
    entry = event[2]
    # [ISSUE_COMMENT] when exactly lefts 0.01 seconds to run the next task =&gt; is_due = False ; next_time_to_run = 0.01
    is_due, next_time_to_run = self.is_due(entry)  
    if is_due:
        verify = heappop(H)
    
    ...

    # [ISSUE_COMMENT] if next_time_to_run = 0.01, adjust(next_time_to_run) = 0 =&gt; 0 or max_interval = max_interval ; max(max_interval, max_interval) = max_interval
    # [ISSUE_COMMENT] max_interval by default is 300 seconds
    return min(adjust(next_time_to_run) or max_interval, max_interval) "><pre class="notranslate"><span class="pl-k">def</span> <span class="pl-en">tick</span>(<span class="pl-s1">self</span>, <span class="pl-s1">event_t</span><span class="pl-c1">=</span><span class="pl-s1">event_t</span>, <span class="pl-s1">min</span><span class="pl-c1">=</span><span class="pl-s1">min</span>,
         <span class="pl-s1">heappop</span><span class="pl-c1">=</span><span class="pl-s1">heapq</span>.<span class="pl-s1">heappop</span>, <span class="pl-s1">heappush</span><span class="pl-c1">=</span><span class="pl-s1">heapq</span>.<span class="pl-s1">heappush</span>,
         <span class="pl-s1">heapify</span><span class="pl-c1">=</span><span class="pl-s1">heapq</span>.<span class="pl-s1">heapify</span>, <span class="pl-s1">mktime</span><span class="pl-c1">=</span><span class="pl-s1">time</span>.<span class="pl-s1">mktime</span>):

    ...

    <span class="pl-s1">event</span> <span class="pl-c1">=</span> <span class="pl-v">H</span>[<span class="pl-c1">0</span>]
    <span class="pl-s1">entry</span> <span class="pl-c1">=</span> <span class="pl-s1">event</span>[<span class="pl-c1">2</span>]
    <span class="pl-c"># [ISSUE_COMMENT] when exactly lefts 0.01 seconds to run the next task =&gt; is_due = False ; next_time_to_run = 0.01</span>
    <span class="pl-s1">is_due</span>, <span class="pl-s1">next_time_to_run</span> <span class="pl-c1">=</span> <span class="pl-s1">self</span>.<span class="pl-en">is_due</span>(<span class="pl-s1">entry</span>)  
    <span class="pl-k">if</span> <span class="pl-s1">is_due</span>:
        <span class="pl-s1">verify</span> <span class="pl-c1">=</span> <span class="pl-en">heappop</span>(<span class="pl-v">H</span>)
    
    ...

    <span class="pl-c"># [ISSUE_COMMENT] if next_time_to_run = 0.01, adjust(next_time_to_run) = 0 =&gt; 0 or max_interval = max_interval ; max(max_interval, max_interval) = max_interval</span>
    <span class="pl-c"># [ISSUE_COMMENT] max_interval by default is 300 seconds</span>
    <span class="pl-k">return</span> <span class="pl-en">min</span>(<span class="pl-en">adjust</span>(<span class="pl-s1">next_time_to_run</span>) <span class="pl-c1">or</span> <span class="pl-s1">max_interval</span>, <span class="pl-s1">max_interval</span>) </pre></div>
<p dir="auto">I am currently running celery 4.0.2 with a single worker like this:</p>
<p dir="auto">celery.py:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="app = Celery('project',
     broker='amqp://jimmy:jimmy123@localhost/jimmy_vhost',
     backend='rpc://',
     include=['project.tasks'])

if __name__ == '__main__':
    app.start()
    app.name"><pre class="notranslate"><code class="notranslate">app = Celery('project',
     broker='amqp://jimmy:jimmy123@localhost/jimmy_vhost',
     backend='rpc://',
     include=['project.tasks'])

if __name__ == '__main__':
    app.start()
    app.name
</code></pre></div>
<p dir="auto">tasks.py:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="from .celery import app
from celery.schedules import schedule
from time import sleep, strftime

app.conf.beat_schedule = {
    'planner_1': {
        'task': 'project.tasks.call_orders',
        'schedule': 1800,
    },
    'planner_2': {
        'task': 'project.tasks.call_inventory',
        'schedule': 900,
    },
}"><pre class="notranslate"><code class="notranslate">from .celery import app
from celery.schedules import schedule
from time import sleep, strftime

app.conf.beat_schedule = {
    'planner_1': {
        'task': 'project.tasks.call_orders',
        'schedule': 1800,
    },
    'planner_2': {
        'task': 'project.tasks.call_inventory',
        'schedule': 900,
    },
}
</code></pre></div>
<p dir="auto">I used the following command to run with beat:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content=" celery -A project worker -l info --concurrency=3 --beat -E"><pre class="notranslate"><code class="notranslate"> celery -A project worker -l info --concurrency=3 --beat -E
</code></pre></div>
<p dir="auto">Right now it is only a single queue with only one worker running.</p>
<blockquote>
<p dir="auto">My question is how to run celery with multiple workers and single queue so that tasks are executed in parallel using multiprocessing without duplication?</p>
</blockquote>
<p dir="auto">I looked up on the internet, how to run celery with multiprocessing. According to this article:</p>
<blockquote>
<p dir="auto"><code class="notranslate">celery worker -l info -P processes -c 16</code> will result in a single message consumer delegating work to 16 OS-level pool processes. Each OS-level process can be assigned to different CPU in a multicore environment, and as such it will process tasks in parallel, but it will not consume messages in parallel.</p>
</blockquote>
<p dir="auto">Can using the -p processes argument solve my problem? Also but what is meant by, "it will process tasks in parallel, but it will not consume messages in parallel"?</p>