anchor.diff:  requests with a queue (optionally bounded) for pending requests that
   have no threads to service them.
   
  -The `size` parameter controls the number of threads, and defaults to the
  -number of cores times 5.
  +The `size` parameter controls the number of threads.
   
   The `queue_size` allows to control the size of the queue of pending
   requests that have no threads to execute them. By default, it is set to
  
positive.code: There are several thread pools, but the important ones include:
  
  `generic`::
      For generic operations (e.g., background node discovery).
      Thread pool type is `scaling`.
  
  `search`::
  
negative.code:     queue_size of `1000`.
  
  `analyze`::
      For analyze requests. Thread pool type is `fixed` with a size of `1`, queue 
      size of `16`.
  
  `write`::
      For single-document index/delete/update and bulk requests. Thread pool type
  