title: Celery run periodic task manually
body: <p>I have a celery tasks</p>
  <p>Part 1</p>
  <pre><code>import time
  @periodic_task(run_every=timedelta(minutes=60), softtimelimit=timedelta(minutes=60).total_seconds())
  def main():
      time.sleep(30)
  </code></pre>
  <p>Part 2</p>
  <pre><code>import time
  @celery.task
  def main():
      time.sleep(30)
  </code></pre>
  <p>As per usual in running celery tasks in part 2. I logged in to my python kernel and ran</p>
  <pre><code>main.delay()
  </code></pre>
  <p>However, for part 1, the same piece of code <code>main.delay()</code> resulted in an exception.</p>
  <p><code>ValueError: Array member at index 0, 3600.0, is of an unsupported type</code></p>
  <p>Anyways i can run this periodic task on demand as i need to debug it.</p>
  <p>I am using celery 4.4.1</p>