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Re: Using Threads?

From: Alfred Perlstein <bright(at)wintelcom(dot)net>
To: Myron Scott <mscott(at)sacadia(dot)com>
Cc: Karel Zak <zakkr(at)zf(dot)jcu(dot)cz>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Using Threads?
Date: 2001-01-02 15:52:34
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Lists: pgsql-hackers
* Myron Scott <mscott(at)sacadia(dot)com> [010102 07:45] wrote:
> Karel Zak wrote:
>  > On Tue, 2 Jan 2001, Myron Scott wrote:
>  >
>  >
>  >> spinlocks rewritten to mutex_
>  >> locktable uses sema_
>  >> some cond_ in bufmgr.c
>  >
>  >
>  > Interesting, have you some comperation between IPC PostgresSQl anf
>  > your thread based PostgreSQL.
>  >
>  > Karel
> Yes, I did some comparisions but it is hard to
> make accurate evaluations on the data.  I basically
> did 1000 inserts from 7.0.2 and the modified verison
> from 8 simultaneous clients.  The original 7.0.2
> was faster by an an order of magnitude.  This needs to
> looked into more though. It was just a rough test b/c clients
> and server all running on the same machine (Ultra 10
> w/512MB RAM).

It's possible what you're seeing is the entire process
wait for a disk IO to complete.

I'm wondering, how many lwps does your system use?  Are all
the threads bound to a single lwp or do you let the threads
manager handle this all for you?

> I don't really know what the impact of changing some of
> the locking mechanisms is.

heh. :)

> On the one hand, there is alot of overhead associated
> with using TAO ORB as the fe<->be protocol.  The 7.0.2
> fe<->be is pretty efficient, TAO with IIOP not as much so.
> At the same time, using prepared statements when doing
> the same insert with different variables over and over
> cuts out re-parsing and planning the statement on every
> execute.
> Lastly,  I really didn't optimize my code at all.  There
> are some places where GetEnv() in called over and over
> to get the thread local variable where it should only
> be called once in the method and reused.
> Speed wasn't the motivation, I just wanted to see if threads
> and PostgreSQL could be done.

Well it'd be better to see if threads+postgresql could be
made faster than non-threaded postgresql.

Do you see yourself with some extra free time in the upcommming
weeks? :)

-Alfred Perlstein - [bright(at)wintelcom(dot)net|alfred(at)freebsd(dot)org]
"I have the heart of a child; I keep it in a jar on my desk."

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