<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 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"> 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" 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><a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="408892295" data-permission-text="Title is private" data-url="https://github.com/celery/celery/issues/5330" data-hovercard-type="issue" data-hovercard-url="/celery/celery/issues/5330/hovercard" href="https://github.com/celery/celery/issues/5330">#5330</a></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>:4.3.0</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:4.3.0 (rhubarb) kombu:4.6.4 py:3.5.6
            billiard:3.6.1.0 py-amqp:2.5.1
platform -&gt; system:Linux arch:64bit, ELF
            kernel version:4.19.71-1-lts imp:CPython
loader   -&gt; celery.loaders.default.Loader
settings -&gt; transport:amqp results:disabled"><pre class="notranslate"><code class="notranslate">software -&gt; celery:4.3.0 (rhubarb) kombu:4.6.4 py:3.5.6
            billiard:3.6.1.0 py-amqp:2.5.1
platform -&gt; system:Linux arch:64bit, ELF
            kernel version:4.19.71-1-lts imp:CPython
loader   -&gt; celery.loaders.default.Loader
settings -&gt; transport:amqp 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>: 3.5.6</li>
<li><strong>Minimal Celery Version</strong>: 4.3.0</li>
<li><strong>Minimal Kombu Version</strong>: 4.6.4</li>
<li><strong>Minimal Broker Version</strong>: RabbitMQ 3.7.15</li>
<li><strong>Minimal Result Backend Version</strong>: 10.4.7-MariaDB</li>
<li><strong>Minimal OS and/or Kernel Version</strong>: Linux 4.19.71-1-lts</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==2.5.1
asn1crypto==0.24.0
Babel==2.7.0
bcrypt==3.1.7
billiard==3.6.1.0
celery==4.3.0
certifi==2019.9.11
cffi==1.12.3
chardet==3.0.4
cryptography==2.7
django-celery-results==1.1.2
flower==0.9.3
idna==2.8
importlib-metadata==0.22
kombu==4.6.4
more-itertools==7.2.0
mysqlclient==1.4.4
paramiko==2.6.0
pycparser==2.19
PyNaCl==1.3.0
pytz==2019.2
requests==2.22.0
requests-toolbelt==0.9.1
six==1.12.0
SQLAlchemy==1.3.8
tornado==5.1.1
urllib3==1.25.3
vine==1.3.0
websockets==7.0
zipp==0.6.0"><pre class="notranslate"><code class="notranslate">amqp==2.5.1
asn1crypto==0.24.0
Babel==2.7.0
bcrypt==3.1.7
billiard==3.6.1.0
celery==4.3.0
certifi==2019.9.11
cffi==1.12.3
chardet==3.0.4
cryptography==2.7
django-celery-results==1.1.2
flower==0.9.3
idna==2.8
importlib-metadata==0.22
kombu==4.6.4
more-itertools==7.2.0
mysqlclient==1.4.4
paramiko==2.6.0
pycparser==2.19
PyNaCl==1.3.0
pytz==2019.2
requests==2.22.0
requests-toolbelt==0.9.1
six==1.12.0
SQLAlchemy==1.3.8
tornado==5.1.1
urllib3==1.25.3
vine==1.3.0
websockets==7.0
zipp==0.6.0
</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>

<details>
<p dir="auto">
</p><div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="@app.task
def add(x, y):
    return x + y

@app.task
def test():
    result_set = ResultSet([])
    add_tasks = add.starmap((i, i) for i in range(10))
    add_result = add_tasks.apply_async()
    result_set.add(add_result)
    return result_set.get(disable_sync_subtasks=False)"><pre class="notranslate"><span class="pl-en">@<span class="pl-s1">app</span>.<span class="pl-s1">task</span></span>
<span class="pl-k">def</span> <span class="pl-en">add</span>(<span class="pl-s1">x</span>, <span class="pl-s1">y</span>):
    <span class="pl-k">return</span> <span class="pl-s1">x</span> <span class="pl-c1">+</span> <span class="pl-s1">y</span>

<span class="pl-en">@<span class="pl-s1">app</span>.<span class="pl-s1">task</span></span>
<span class="pl-k">def</span> <span class="pl-en">test</span>():
    <span class="pl-s1">result_set</span> <span class="pl-c1">=</span> <span class="pl-v">ResultSet</span>([])
    <span class="pl-s1">add_tasks</span> <span class="pl-c1">=</span> <span class="pl-s1">add</span>.<span class="pl-en">starmap</span>((<span class="pl-s1">i</span>, <span class="pl-s1">i</span>) <span class="pl-k">for</span> <span class="pl-s1">i</span> <span class="pl-c1">in</span> <span class="pl-en">range</span>(<span class="pl-c1">10</span>))
    <span class="pl-s1">add_result</span> <span class="pl-c1">=</span> <span class="pl-s1">add_tasks</span>.<span class="pl-en">apply_async</span>()
    <span class="pl-s1">result_set</span>.<span class="pl-en">add</span>(<span class="pl-s1">add_result</span>)
    <span class="pl-k">return</span> <span class="pl-s1">result_set</span>.<span class="pl-en">get</span>(<span class="pl-s1">disable_sync_subtasks</span><span class="pl-c1">=</span><span class="pl-c1">False</span>)</pre></div>
<p dir="auto"></p>
</details>
<h1 dir="auto">Expected Behavior</h1>

<p dir="auto">The tasks runs successfully, with the acceptance of possible deadlock</p>
<h1 dir="auto">Actual Behavior</h1>

<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="Traceback (most recent call last):
  File &quot;/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/app/trace.py&quot;, line 385, in trace_task
    R = retval = fun(*args, **kwargs)
  File &quot;/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/app/trace.py&quot;, line 648, in __protected_call__
    return self.run(*args, **kwargs)
  File &quot;/home/gsfish/work/netease/project/scan_detect/tasks.py&quot;, line 106, in test
    return result_set.get(disable_sync_subtasks=False)
  File &quot;/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/result.py&quot;, line 697, in get
    on_interval=on_interval,
  File &quot;/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/result.py&quot;, line 765, in join
    interval=interval, no_ack=no_ack, on_interval=on_interval,
  File &quot;/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/result.py&quot;, line 205, in get
    assert_will_not_block()
  File &quot;/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/result.py&quot;, line 41, in assert_will_not_block
    raise RuntimeError(E_WOULDBLOCK)
RuntimeError: Never call result.get() within a task!
See http://docs.celeryq.org/en/latest/userguide/tasks.html#task-synchronous-subtasks"><pre class="notranslate"><code class="notranslate">Traceback (most recent call last):
  File "/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/app/trace.py", line 385, in trace_task
    R = retval = fun(*args, **kwargs)
  File "/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/app/trace.py", line 648, in __protected_call__
    return self.run(*args, **kwargs)
  File "/home/gsfish/work/netease/project/scan_detect/tasks.py", line 106, in test
    return result_set.get(disable_sync_subtasks=False)
  File "/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/result.py", line 697, in get
    on_interval=on_interval,
  File "/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/result.py", line 765, in join
    interval=interval, no_ack=no_ack, on_interval=on_interval,
  File "/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/result.py", line 205, in get
    assert_will_not_block()
  File "/home/gsfish/.pyenv/versions/scan_detect/lib/python3.5/site-packages/celery/result.py", line 41, in assert_will_not_block
    raise RuntimeError(E_WOULDBLOCK)
RuntimeError: Never call result.get() within a task!
See http://docs.celeryq.org/en/latest/userguide/tasks.html#task-synchronous-subtasks
</code></pre></div>
<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 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.<br>
This relates to 4.3.0, not 4.4.x</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"> 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" checked=""> 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><a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="450565046" data-permission-text="Title is private" data-url="https://github.com/celery/kombu/issues/1052" data-hovercard-type="issue" data-hovercard-url="/celery/kombu/issues/1052/hovercard" href="https://github.com/celery/kombu/issues/1052">celery/kombu#1052</a></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>: <code class="notranslate">4.3.0 (rhubarb)</code></p>

<details>
<summary><b><code class="notranslate">
</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:4.3.0 (rhubarb) kombu:4.6.0 py:3.7.3
            billiard:3.6.0.0 redis:3.2.1
platform -&gt; system:Linux arch:64bit
            kernel version:4.15.0-50-generic imp:CPython
loader   -&gt; celery.loaders.app.AppLoader
settings -&gt; transport:redis results:redis://localhost:6379/1"><pre class="notranslate"><code class="notranslate">software -&gt; celery:4.3.0 (rhubarb) kombu:4.6.0 py:3.7.3
            billiard:3.6.0.0 redis:3.2.1
platform -&gt; system:Linux arch:64bit
            kernel version:4.15.0-50-generic imp:CPython
loader   -&gt; celery.loaders.app.AppLoader
settings -&gt; transport:redis results:redis://localhost:6379/1
</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>: Unknown</li>
<li><strong>Minimal Celery Version</strong>: N/A or Unknown</li>
<li><strong>Minimal Kombu Version</strong>: 4.6.0</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="flower==0.9.3
  - babel [required: &gt;=1.0,&lt;3.0.0, installed: 2.7.0]
    - pytz [required: &gt;=2015.7, installed: 2019.1]
  - celery [required: &gt;=3.1.0, installed: 4.3.0]
    - billiard [required: &gt;=3.6.0,&lt;4.0, installed: 3.6.0.0]
    - kombu [required: &gt;=4.4.0,&lt;5.0, installed: 4.6.0]
      - amqp [required: &gt;=2.5.0,&lt;3.0, installed: 2.5.0]
        - vine [required: &gt;=1.1.3,&lt;5.0.0a1, installed: 1.3.0]
    - pytz [required: &gt;dev, installed: 2019.1]
    - vine [required: &gt;=1.3.0, installed: 1.3.0]
  - pytz [required: Any, installed: 2019.1]
  - tornado [required: &gt;=4.2.0,&lt;6.0.0, installed: 5.1.1]"><pre class="notranslate"><code class="notranslate">flower==0.9.3
  - babel [required: &gt;=1.0,&lt;3.0.0, installed: 2.7.0]
    - pytz [required: &gt;=2015.7, installed: 2019.1]
  - celery [required: &gt;=3.1.0, installed: 4.3.0]
    - billiard [required: &gt;=3.6.0,&lt;4.0, installed: 3.6.0.0]
    - kombu [required: &gt;=4.4.0,&lt;5.0, installed: 4.6.0]
      - amqp [required: &gt;=2.5.0,&lt;3.0, installed: 2.5.0]
        - vine [required: &gt;=1.1.3,&lt;5.0.0a1, installed: 1.3.0]
    - pytz [required: &gt;dev, installed: 2019.1]
    - vine [required: &gt;=1.3.0, installed: 1.3.0]
  - pytz [required: Any, installed: 2019.1]
  - tornado [required: &gt;=4.2.0,&lt;6.0.0, installed: 5.1.1]
</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">
1. run celery 4.3.0 with a fresh install (make sure you got kombu 4.6.0)
2. run celery inspect ping
3. profit.
</p>
</details>
<h1 dir="auto">Expected Behavior</h1>

<p dir="auto">Ping should work</p>
<h1 dir="auto">Actual Behavior</h1>

<p dir="auto">ping says no nodes resonded</p>