HP OpenVMS Systems

Application fails on SMP multiprocessor?

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The Question is:

 
I have an application, running on a Dual Processor COMPAQ AlphaServer DS20E 500
 MHzP running OpenVMS V7.1-2.
 
The application is fully event driven making use of the synchronous QIO system
 service to process both Mailbox and Socket (network) events. The wflor system
 service is used to determine when an event has been triggered. The readef
 system service is then u
sed to determine which event/s needs to be processed. The app is aware that
 both events may be triggered at the same time.
 
The App works perfectly on a SINGLE processor COMPAQ AlphaServer.
On the DUAL Processor AlphaServer I tend to loose anything from 1-4 mailbox
 messages.
 
Please tell me why this is happening?
 
Thanks in advance
Daya Subban
 
 

The Answer is :

 
  Your application code very likely has a latent synchronization bug.
 
  Please see topic 1661 for one list of the usual sorts of SMP bugs
  that can arise within application code.
 
  ASTs or threads are often preferable to event flags, both in terms of
  the limits on the numbers of event flags that can be active at one
  time (32 event flags is the limit for the $wflor service, for instance)
  and in terms of the ease of overlapping the application activity.
 

  

     

     
answer written or last revised on ( 15-MAY-2000 )
     
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