***BOGO*** Re: multiple mysqld process? is this correct?

[Joerg Bruehe <joerg@xxxxxxxxx>]

Hi Saravanan, all,


Saravanan wrote (top-posting re-ordered):
> --- On Mon, 5/26/08, Joerg Bruehe <joerg@xxxxxxxxx> wrote:
>
> > From: Joerg Bruehe <joerg@xxxxxxxxx>
> > Subject: Re: multiple mysqld process? is this correct?
> > [[...]]
> > Saravanan wrote:
> > > Hi all,
> > >
> > > I started the sql server with 5.0.51b but i suddenly
> > noticed that mysqld is running with multiple process in top
> > >   [[...]]
> > >
> > > is this correct or false? pls let me know asap
> > >
> > > [[...]]
> > This is dependent on how your Linux kernel handles
> > threading, and which 
> > MySQL package you installed.
> >
> > The MySQL server runs multithreaded, and in older Linux
> > versions such 
> > threads were displayed by "ps" like independent
> > processes.
> > Only in newer versions, and when "NPTL" is used
> > (not the older 
> > "linuxthread"), will the several threads be shown
> > as a single process.
> Hi jorg,
>
> wont this(running as multiple process) create any big problem with
> production datas? But it didnt show any error or warnings in mysql err
> log file.

1) I wrote "displayed as": It is several threads within one process,
   just "ps" (or "top") sometimes display them like several processes.

2) This would not be a problem specific to "production data":
   *If* synchronization among these threads (on shared resources) would
   not work properly, it would affect test data as well.

3) Synchronization is possible between threads as well as processes,
   a multi-process server could work as correct as a multi-thread one.
(But threads use less resources than processes, so they perform better.)

>
> [[...]]
>

HTH,
Jörg

--
Joerg Bruehe,  MySQL Build Team,  joerg@xxxxxxxxx
Sun Microsystems GmbH,   Sonnenallee 1,   D-85551 Kirchheim-Heimstetten
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