Re: Performance under contention

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От Ivan Voras
Тема Re: Performance under contention
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Msg-id iclle6$jdq$1@dough.gmane.org
обсуждение исходный текст
Ответ на Re: Performance under contention  ("Kevin Grittner")
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Performance under contention  (Ivan Voras, )
 Re: Performance under contention  ("Kevin Grittner", )
  Re: Performance under contention  (Ivan Voras, )
   Re: Performance under contention  (Jignesh Shah, )
    Re: Performance under contention  (Omar Kilani, )
   Re: Performance under contention  ("Kevin Grittner", )
    Re: Performance under contention  (Ivan Voras, )
     Re: Performance under contention  (Craig Ringer, )
      Re: Performance under contention  (Ivan Voras, )
      Re: Performance under contention  (Vitalii Tymchyshyn, )
       Re: Performance under contention  ("Kevin Grittner", )
 Re: Performance under contention  ("Kevin Grittner", )
  Re: Performance under contention  (Ivan Voras, )
 Re: Performance under contention  (Greg Smith, )
  Re: Performance under contention  (Ivan Voras, )
 Re: Performance under contention  (Robert Haas, )
  Re: Performance under contention  (Robert Haas, )
  Re: Performance under contention  (Jignesh Shah, )
   Re: Performance under contention  (Jignesh Shah, )
   Re: Performance under contention  (Robert Haas, )
    Re: Performance under contention  (Tom Lane, )
     Re: Performance under contention  (Dave Crooke, )
     Re: Performance under contention  (Robert Haas, )
    Re: Performance under contention  (Ivan Voras, )
     Re: Performance under contention  (Robert Haas, )
      Re: Performance under contention  (Ivan Voras, )
      Re: Performance under contention  (Віталій Тимчишин, )
       Re: Performance under contention  (Ivan Voras, )
       Re: Performance under contention  (Robert Haas, )
        Re: Performance under contention  (Robert Haas, )
         Re: Performance under contention  (Tom Lane, )
          Re: Performance under contention  (Robert Haas, )
           Re: Performance under contention  (Tom Lane, )
            Re: Performance under contention  (Robert Haas, )
On 11/22/10 18:47, Kevin Grittner wrote:
> Ivan Voras<>  wrote:
>
>> It looks like a hack
>
> Not to everyone.  In the referenced section, Hellerstein,
> Stonebraker and Hamilton say:
>
> "any good multi-user system has an admission control policy"
>
> In the case of PostgreSQL I understand the counter-argument,
> although I'm inclined to think that it's prudent for a product to
> limit resource usage to a level at which it can still function well,
> even if there's an external solution which can also work, should
> people use it correctly.  It seems likely that a mature admission
> control policy could do a better job of managing some resources than
> an external product could.

I didn't think it would be that useful but yesterday I did some
(unrelated) testing with MySQL and it looks like its configuration
parameter "thread_concurrency" does something to that effect.

Initially I thought it is equivalent to PostgreSQL's max_connections but
no, connections can grow (MySQL spawns a thread per connection by
default) but the actual concurrency is limited in some way by this
parameter.

The comment for the parameter says "# Try number of CPU's*2 for
thread_concurrency" but obviously it would depend a lot on the
real-world load.


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