<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 checked the <a href="https://github.com/celery/celery/issues?q=is%3Aissue+label%3A%22Issue+Type%3A+Enhancement%22+-label%3A%22Category%3A+Documentation%22">issues list</a><br>
for similar or identical enhancement to an existing feature.</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%22Issue+Type%3A+Enhancement%22+-label%3A%22Category%3A+Documentation%22">pull requests list</a><br>
for existing proposed enhancements.</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 if the same enhancement was already implemented in the<br>
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 in this issue<br>
(If there are none, check this box anyway).</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>
<h1 dir="auto">Brief Summary</h1>
<p dir="auto">I have a form in my Django app which creates an object <code class="notranslate">car</code> (it does not matter that I use Django, it's just to explain the main idea). I use celery to run operations, once new object <code class="notranslate">car</code> was created (by using <code class="notranslate">post_save</code> signal). I have an option to delete the <code class="notranslate">car</code>. So it should delete it from the database and it should run deleting operations with Celery. I use <code class="notranslate">pre_save</code> for that.</p>
<p dir="auto">The problem is as following: The creating operations can take some time (a few minutes). This means, that user can create a new <code class="notranslate">car</code> and while running the Celery creation operation, he will ask to delete the object. The celery tasks:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="@app.task(bind=True)
def create_car(self, car_pk):
    from cars.models import car
    if car_pk is None or not isinstance(car_pk,int):
        return False
    car_obj = car.objects.get(pk=car_pk)
    
    # Creation operations
    
    car_obj.save()
    return creation_status

@app.task(bind=True)
def delete_car(self, car_pk):
    from cars.models import car
    if car_pk is None or not isinstance(car_pk,int):
        return False
    car_obj = car.objects.get(pk=car_pk)
    
    # deletion operations
    
    return deletion_status"><pre class="notranslate"><code class="notranslate">@app.task(bind=True)
def create_car(self, car_pk):
    from cars.models import car
    if car_pk is None or not isinstance(car_pk,int):
        return False
    car_obj = car.objects.get(pk=car_pk)
    
    # Creation operations
    
    car_obj.save()
    return creation_status

@app.task(bind=True)
def delete_car(self, car_pk):
    from cars.models import car
    if car_pk is None or not isinstance(car_pk,int):
        return False
    car_obj = car.objects.get(pk=car_pk)
    
    # deletion operations
    
    return deletion_status
</code></pre></div>
<p dir="auto">So my question is - how should I handle this case? Can I somehow "stop" the creation task? Or can I somehow "wait" until the creation task finish and then do the deletion operations?</p>
<p dir="auto">If both cases can be achieved, I would be glad to see them both.</p>
<h1 dir="auto">Design</h1>
<h2 dir="auto">Architectural Considerations</h2>

<p dir="auto">None</p>
<h2 dir="auto">Proposed Behavior</h2>

<h2 dir="auto">Proposed UI/UX</h2>

<h2 dir="auto">Diagrams</h2>

<p dir="auto">N/A</p>
<h2 dir="auto">Alternatives</h2>

<p dir="auto">None</p>
<h1 dir="auto">Checklist</h1>

<ul class="contains-task-list">
<li>[ x] 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>[ x] 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>[ x] 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>[ x] 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>[ x] 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>[ x] 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>[x ] 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>[ x] 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>[ x] 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>[x ] I have tried reproducing the issue on more than one Python version<br>
and/or implementation.</li>
<li>[ x] I have tried reproducing the issue on more than one message broker and/or<br>
result backend.</li>
<li>[x ] 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>[ x] 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"><strong>Celery version</strong>: celery 4.4.7</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=""><pre class="notranslate"><code class="notranslate"></code></pre></div>
<p dir="auto">No output.</p>
<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>: python 3.8</li>
<li><strong>Minimal Celery Version</strong>: celery 4.4.7</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=""><pre class="notranslate"><code class="notranslate"></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>
  I expect this line of  code `fs = s3fs.S3FileSystem(anon=True)` to work, but whenever it reaches this stage celery hangs.
<h1 dir="auto">Actual Behavior</h1>
 Nothing Happens.