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How can I perform calculations in the background
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You can use this code in the task server module to run a background thread in 
the web application once a 3 minutes (can be changed by setting interval) 
to perform some calculations:

.. code-block:: py

  import threading
  import time
  import traceback
  
  def background(task):
      interval = 3 * 60
      time.sleep(interval)
      while True:
          if not time:
              return
          with task.lock('background'):
              try:
                  print('background')            
                  # some code to execute in background for example:
                  # tracks = task.tracks.copy()
                  # tracks.open()
                  # for t in tracks:
                  #     t.edit()
                  #     t.sold.value = #some value
                  #     t.post()
                  # tracks.apply()    
              except Exception as e:
                  traceback.print_exc()
          time.sleep(interval)
  
  def on_created(task):
      bg = threading.Thread(target=background, args=(task,))
      bg.daemon = True
      bg.start()

.. note::
  When multiple web applications are running in parallel processes, the background 
  function will be executed in each process. To prevent simultaneous execution 
  of this function, we use the lock method of the task.