HP OpenVMS Systems

Guidelines for AST routines?

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The Question is:

 
Say you have a large amount of postprocessing to do on behalf of a completed
$QIO.
Are there any guidelines to which and how much of such postprocessing you
should put in an associated AST as opposed to the main loop?
 
 

The Answer is :

 
  Based on your "large amount of post-processing" phrasing and based on
  the question that is being asked, the OpenVMS Wizard would assume you
  will want to use a work queue or similar and perform the post-processing
  in the mainline.  Not in the AST routine.
 
  The more code you put into the AST completion routine, the less the
  amount of parallel AST activity that can occur, and the less effective
  that the resulting the code will be with handling bursts of activity.
  Operations that will cause waits are particularly to be avoided in
  ASTs when feasible.
 
  As you are on OpenVMS Alpha, you will particularly also want to look
  at DECthreads and multi-threading.
 

  

     

     
answer written or last revised on ( 18-NOV-1999 )
     
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