Re: refusing connections based on load ...

Doug McNaught wrote:
> A very valid objection.  I'm also dubious as to the utility of the
> whole concept.  What happens when Sendmail refuses a message based on
> load?  It is requeued on the sending end to be tried later.  What
> happens when PG refuses a new client connection based on load?  The
> application stops working.  Is this really better than having slow
> response time because the server is thrashing?
   That's exactly the point why I suggested to delay transaction   starts instead. The client app allways gets  the
connection.  Doing  dialog  steps inside of open transactions is allways a   bad design, leading to a couple  of
problems (coffee  break   with  open  locks),  so  we can assume that if an application   starts a transaction, it'll
keepthis one backend as busy  as   possible until the transactions end.
 
   Processing  too  many transactions parallel is what get's the   system  into  heavy  swapping  and   exponential
usage  of   resources. So if we delay starting transactions if the system   load is above the limit, we probably
speedupthe overall  per   transaction  response  time,  increasing  the  througput. And   that's what this discussion
isall about, no?
 


Jan

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