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

<ul class="contains-task-list">
<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 class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> 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>[ 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 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><a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="299009247" data-permission-text="Title is private" data-url="https://github.com/celery/celery/issues/4551" data-hovercard-type="issue" data-hovercard-url="/celery/celery/issues/4551/hovercard?comment_id=367607234&amp;comment_type=issue_comment" href="https://github.com/celery/celery/issues/4551#issuecomment-367607234">#4551 (comment)</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: 4.3.0</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="celeryworker_1  | [2019-09-30 12:10:16,485: INFO/MainProcess] Received task: django_dask.users.tasks.get_users_count[0b2cd4f1-e6a9-41af-974c-bd9a60ddc648]"><pre class="notranslate"><code class="notranslate">celeryworker_1  | [2019-09-30 12:10:16,485: INFO/MainProcess] Received task: django_dask.users.tasks.get_users_count[0b2cd4f1-e6a9-41af-974c-bd9a60ddc648]
</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>: 3.6.6</li>
<li><strong>Minimal Celery Version</strong>: 4.3.0</li>
<li><strong>Minimal Kombu Version</strong>: Unknown</li>
<li><strong>Minimal Broker Version</strong>: redis==3.3.8</li>
<li><strong>Minimal Result Backend Version</strong>: N/A or Unknown</li>
<li><strong>Minimal OS and/or Kernel Version</strong>: Docker image python:3.6.6</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>
<p dir="auto">Install cookiecutter django with celery and add dask package. You can either add dask as a service in docker-compose or initiate a local cluster within the <code class="notranslate">{app}/users/app.py</code></p>
<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=""><pre class="notranslate"><code class="notranslate">
</code></pre></div>
<p dir="auto"></p>
</details>
<h1 dir="auto">Expected Behavior</h1>
<p dir="auto">That I am able to further create subprocesses within the task by triggering dask within celery task.</p>
<h1 dir="auto">Actual Behavior</h1>
<p dir="auto">I am trying to start subprocesses of scikit learn within a task of celery. I am aware that joblib will run it sequentially if it is already running in a process. Therefore, based on <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="299009247" data-permission-text="Title is private" data-url="https://github.com/celery/celery/issues/4551" data-hovercard-type="issue" data-hovercard-url="/celery/celery/issues/4551/hovercard?comment_id=367607234&amp;comment_type=issue_comment" href="https://github.com/celery/celery/issues/4551#issuecomment-367607234">#4551 (comment)</a>, I have installed Dask and changed joblib <code class="notranslate">parallel_backend</code> to dask and run the below function one time normally; i.e. <code class="notranslate">get_users_count()</code> and another time with <code class="notranslate">apply_async()</code>; i.e., <code class="notranslate">get_users_count.apply_async()</code>. The former ran successfully and the later showed that the worker has received the message (as shown in the <code class="notranslate">celery report</code> above). and celery worker hangs and become unresponsive, I tried to access the worker in flower, however I received <code class="notranslate">Unknown worker 'celery@0bb51b1f7782'</code> as if it is died (which was previously accessible before calling the function).</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="@celery_app.task()
def get_users_count():
    &quot;&quot;&quot;A pointless Celery task to demonstrate usage.&quot;&quot;&quot;
    from sklearn.utils import parallel_backend
    import numpy as np
    from sklearn.cluster import KMeans

    parallel_backend(&quot;dask&quot;)
    kmeans = KMeans(n_jobs=-1, n_init=5, verbose=10)
    kmeans.fit(np.random.rand(1000).reshape(500, 2))

    return User.objects.count()"><pre class="notranslate"><code class="notranslate">@celery_app.task()
def get_users_count():
    """A pointless Celery task to demonstrate usage."""
    from sklearn.utils import parallel_backend
    import numpy as np
    from sklearn.cluster import KMeans

    parallel_backend("dask")
    kmeans = KMeans(n_jobs=-1, n_init=5, verbose=10)
    kmeans.fit(np.random.rand(1000).reshape(500, 2))

    return User.objects.count()
</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" 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"> 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" checked=""> 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>
<p dir="auto">error when get task state or other attribute value.</p>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="&gt;&gt;&gt; taskid=&quot;d7b78dfa-5602-4a4e-bf4e-dff1c9a8e46e&quot;
&gt;&gt;&gt; task = TAA.AsyncResult(taskid)
&gt;&gt;&gt;
&gt;&gt;&gt; task.state
Traceback (most recent call last):
  File &quot;&lt;stdin&gt;&quot;, line 1, in &lt;module&gt;
  File &quot;/usr/local/lib/python3.7/site-packages/celery/result.py&quot;, line 473, in state
    return self._get_task_meta()['status']
  File &quot;/usr/local/lib/python3.7/site-packages/celery/result.py&quot;, line 412, in _get_task_meta
    return self._maybe_set_cache(self.backend.get_task_meta(self.id))
  File &quot;/usr/local/lib/python3.7/site-packages/celery/backends/base.py&quot;, line 386, in get_task_meta
    meta = self._get_task_meta_for(task_id)
  File &quot;/usr/local/lib/python3.7/site-packages/celery/backends/base.py&quot;, line 730, in _get_task_meta_for
    return self.decode_result(meta)
  File &quot;/usr/local/lib/python3.7/site-packages/celery/backends/base.py&quot;, line 305, in decode_result
    return self.meta_from_decoded(self.decode(payload))
  File &quot;/usr/local/lib/python3.7/site-packages/celery/backends/base.py&quot;, line 301, in meta_from_decoded
    meta['result'] = self.exception_to_python(meta['result'])
  File &quot;/usr/local/lib/python3.7/site-packages/celery/backends/base.py&quot;, line 281, in exception_to_python
    exc = cls(*exc_msg if isinstance(exc_msg, tuple) else exc_msg)
TypeError: __init__() missing 2 required positional arguments: 'doc' and 'pos'"><pre class="notranslate"><span class="pl-c1">&gt;&gt;</span><span class="pl-c1">&gt;</span> <span class="pl-s1">taskid</span><span class="pl-c1">=</span><span class="pl-s">"d7b78dfa-5602-4a4e-bf4e-dff1c9a8e46e"</span>
<span class="pl-c1">&gt;&gt;</span><span class="pl-c1">&gt;</span> <span class="pl-s1">task</span> <span class="pl-c1">=</span> <span class="pl-v">TAA</span>.<span class="pl-v">AsyncResult</span>(<span class="pl-s1">taskid</span>)
<span class="pl-c1">&gt;&gt;</span><span class="pl-c1">&gt;</span>
<span class="pl-c1">&gt;&gt;</span><span class="pl-c1">&gt;</span> <span class="pl-s1">task</span>.<span class="pl-s1">state</span>
<span class="pl-v">Traceback</span> (<span class="pl-s1">most</span> <span class="pl-s1">recent</span> <span class="pl-s1">call</span> <span class="pl-s1">last</span>):
  <span class="pl-v">File</span> <span class="pl-s">"&lt;stdin&gt;"</span>, <span class="pl-s1">line</span> <span class="pl-c1">1</span>, <span class="pl-s1">in</span> <span class="pl-c1">&lt;</span><span class="pl-s1">module</span><span class="pl-c1">&gt;</span>
  <span class="pl-v">File</span> <span class="pl-s">"/usr/local/lib/python3.7/site-packages/celery/result.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">473</span>, <span class="pl-s1">in</span> <span class="pl-s1">state</span>
    <span class="pl-k">return</span> <span class="pl-s1">self</span>.<span class="pl-en">_get_task_meta</span>()[<span class="pl-s">'status'</span>]
  <span class="pl-v">File</span> <span class="pl-s">"/usr/local/lib/python3.7/site-packages/celery/result.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">412</span>, <span class="pl-s1">in</span> <span class="pl-s1">_get_task_meta</span>
    <span class="pl-k">return</span> <span class="pl-s1">self</span>.<span class="pl-en">_maybe_set_cache</span>(<span class="pl-s1">self</span>.<span class="pl-s1">backend</span>.<span class="pl-en">get_task_meta</span>(<span class="pl-s1">self</span>.<span class="pl-s1">id</span>))
  <span class="pl-v">File</span> <span class="pl-s">"/usr/local/lib/python3.7/site-packages/celery/backends/base.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">386</span>, <span class="pl-s1">in</span> <span class="pl-s1">get_task_meta</span>
    <span class="pl-s1">meta</span> <span class="pl-c1">=</span> <span class="pl-s1">self</span>.<span class="pl-en">_get_task_meta_for</span>(<span class="pl-s1">task_id</span>)
  <span class="pl-v">File</span> <span class="pl-s">"/usr/local/lib/python3.7/site-packages/celery/backends/base.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">730</span>, <span class="pl-s1">in</span> <span class="pl-s1">_get_task_meta_for</span>
    <span class="pl-k">return</span> <span class="pl-s1">self</span>.<span class="pl-en">decode_result</span>(<span class="pl-s1">meta</span>)
  <span class="pl-v">File</span> <span class="pl-s">"/usr/local/lib/python3.7/site-packages/celery/backends/base.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">305</span>, <span class="pl-s1">in</span> <span class="pl-s1">decode_result</span>
    <span class="pl-k">return</span> <span class="pl-s1">self</span>.<span class="pl-en">meta_from_decoded</span>(<span class="pl-s1">self</span>.<span class="pl-en">decode</span>(<span class="pl-s1">payload</span>))
  <span class="pl-v">File</span> <span class="pl-s">"/usr/local/lib/python3.7/site-packages/celery/backends/base.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">301</span>, <span class="pl-s1">in</span> <span class="pl-s1">meta_from_decoded</span>
    <span class="pl-s1">meta</span>[<span class="pl-s">'result'</span>] <span class="pl-c1">=</span> <span class="pl-s1">self</span>.<span class="pl-en">exception_to_python</span>(<span class="pl-s1">meta</span>[<span class="pl-s">'result'</span>])
  <span class="pl-v">File</span> <span class="pl-s">"/usr/local/lib/python3.7/site-packages/celery/backends/base.py"</span>, <span class="pl-s1">line</span> <span class="pl-c1">281</span>, <span class="pl-s1">in</span> <span class="pl-s1">exception_to_python</span>
    <span class="pl-s1">exc</span> <span class="pl-c1">=</span> <span class="pl-en">cls</span>(<span class="pl-c1">*</span><span class="pl-s1">exc_msg</span> <span class="pl-k">if</span> <span class="pl-en">isinstance</span>(<span class="pl-s1">exc_msg</span>, <span class="pl-s1">tuple</span>) <span class="pl-k">else</span> <span class="pl-s1">exc_msg</span>)
<span class="pl-v">TypeError</span>: <span class="pl-en">__init__</span>() <span class="pl-s1">missing</span> <span class="pl-c1">2</span> <span class="pl-s1">required</span> <span class="pl-s1">positional</span> <span class="pl-s1">arguments</span>: <span class="pl-s">'doc'</span> <span class="pl-c1">and</span> <span class="pl-s">'pos'</span></pre></div>
<p dir="auto">The content of the taskid task in redis:</p>
<div class="highlight highlight-source-json notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="{
  &quot;status&quot;: &quot;FAILURE&quot;,
  &quot;result&quot;: {
    &quot;exc_type&quot;: &quot;JSONDecodeError&quot;,
    &quot;exc_message&quot;: [
      &quot;Expecting ',' delimiter: line 1 column 528408 (char 528407)&quot;
    ],
    &quot;exc_module&quot;: &quot;json.decoder&quot;
  },
  &quot;traceback&quot;: &quot;Traceback (most recent call last):\n  File \&quot;/usr/local/lib/python3.7/site-packages/celery/app/trace.py\&quot;, line 385, in trace_task\n    R = retval = fun(*args, **kwargs)\n  File \&quot;/usr/local/lib/python3.7/site-packages/celery/app/trace.py\&quot;, line 648, in __protected_call__\n    return self.run(*args, **kwargs)\n  File \&quot;/Users/youzhengchuan/PycharmProjects/collector/pcdn/analysis/__init__.py\&quot;, line 14, in telegraf_abnormal_analysis\n    ret = taa.analysis(sts, ets, lot)\n  File \&quot;/Users/youzhengchuan/PycharmProjects/collector/pcdn/analysis/telegraf_abnormal_analysis.py\&quot;, line 42, in analysis\n    online = self._query.groupby(**params)\n  File \&quot;/Users/youzhengchuan/PycharmProjects/collector/pcdn/analysis/query.py\&quot;, line 35, in groupby\n    ret = self._query.groupby(**params)\n  File \&quot;/usr/local/lib/python3.7/site-packages/pydruid/client.py\&quot;, line 306, in groupby\n    return self._post(query)\n  File \&quot;/usr/local/lib/python3.7/site-packages/pydruid/client.py\&quot;, line 571, in _post\n    query.parse(data)\n  File \&quot;/usr/local/lib/python3.7/site-packages/pydruid/query.py\&quot;, line 53, in parse\n    res = json.loads(self.result_json)\n  File \&quot;/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/__init__.py\&quot;, line 348, in loads\n    return _default_decoder.decode(s)\n  File \&quot;/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/decoder.py\&quot;, line 337, in decode\n    obj, end = self.raw_decode(s, idx=_w(s, 0).end())\n  File \&quot;/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/decoder.py\&quot;, line 353, in raw_decode\n    obj, end = self.scan_once(s, idx)\njson.decoder.JSONDecodeError: Expecting ',' delimiter: line 1 column 528408 (char 528407)\n&quot;,
  &quot;children&quot;: [],
  &quot;task_id&quot;: &quot;d7b78dfa-5602-4a4e-bf4e-dff1c9a8e46e&quot;,
  &quot;date_done&quot;: &quot;2019-09-04T08:11:17.388695&quot;
}"><pre class="notranslate">{
  <span class="pl-ent">"status"</span>: <span class="pl-s"><span class="pl-pds">"</span>FAILURE<span class="pl-pds">"</span></span>,
  <span class="pl-ent">"result"</span>: {
    <span class="pl-ent">"exc_type"</span>: <span class="pl-s"><span class="pl-pds">"</span>JSONDecodeError<span class="pl-pds">"</span></span>,
    <span class="pl-ent">"exc_message"</span>: [
      <span class="pl-s"><span class="pl-pds">"</span>Expecting ',' delimiter: line 1 column 528408 (char 528407)<span class="pl-pds">"</span></span>
    ],
    <span class="pl-ent">"exc_module"</span>: <span class="pl-s"><span class="pl-pds">"</span>json.decoder<span class="pl-pds">"</span></span>
  },
  "traceback": "Traceback (most recent call last):\n  File \"/usr/local/lib/python3.7/site-packages/celery/app/trace.py\", line 385, in trace_task\n    R = retval = fun(*args, **kwargs)\n  File \"/usr/local/lib/python3.7/site-packages/celery/app/trace.py\", line 648, in __protected_call__\n    return self.run(*args, **kwargs)\n  File \"/Users/youzhengchuan/PycharmProjects/collector/pcdn/analysis/__init__.py\", line 14, in telegraf_abnormal_analysis\n    ret = taa.analysis(sts, ets, lot)\n  File \"/Users/youzhengchuan/PycharmProjects/collector/pcdn/analysis/telegraf_abnormal_analysis.py\", line 42, in analysis\n    online = self._query.groupby(**params)\n  File \"/Users/youzhengchuan/PycharmProjects/collector/pcdn/analysis/query.py\", line 35, in groupby\n    ret = self._query.groupby(**params)\n  File \"/usr/local/lib/python3.7/site-packages/pydruid/client.py\", line 306, in groupby\n    return self._post(query)\n  File \"/usr/local/lib/python3.7/site-packages/pydruid/client.py\", line 571, in _post\n    query.parse(data)\n  File \"/usr/local/lib/python3.7/site-packages/pydruid/query.py\", line 53, in parse\n    res = json.loads(self.result_json)\n  File \"/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/__init__.py\", line 348, in loads\n    return _default_decoder.decode(s)\n  File \"/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/decoder.py\", line 337, in decode\n    obj, end = self.raw_decode(s, idx=_w(s, 0).end())\n  File \"/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/decoder.py\", line 353, in raw_decode\n    obj, end = self.scan_once(s, idx)\njson.decoder.JSONDecodeError: Expecting ',' delimiter: line 1 column 528408 (char 528407)\n",
  <span class="pl-ent">"children"</span>: [],
  <span class="pl-ent">"task_id"</span>: <span class="pl-s"><span class="pl-pds">"</span>d7b78dfa-5602-4a4e-bf4e-dff1c9a8e46e<span class="pl-pds">"</span></span>,
  <span class="pl-ent">"date_done"</span>: <span class="pl-s"><span class="pl-pds">"</span>2019-09-04T08:11:17.388695<span class="pl-pds">"</span></span>
}</pre></div>
<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>:</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"></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>: N/A or Unknown</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>

<h1 dir="auto">Actual Behavior</h1>