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From:Jeremy Zawodny Date:December 30 2002 9:50pm
Subject:Re: Replication priority / speed
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On Mon, Dec 30, 2002 at 03:48:30PM -0600, Dan Nelson wrote:
> In the last episode (Dec 30), Matt Sturtz said:
> > Hello, Jeremy, et al--  Thanks for the reply before...  Further questions:
> > >> Is it possible to set either set the priority ('nice') of the
> > >> Slave thread down so it doesn't do that?
> > >
> > > The slave thread only?  No, not really.  You could nice MySQL when
> > > you start it up.  But I'm not sure how much effect (positive or
> > > negative) that'd have.
> > 
> > When I run "show [full] processlist", there's an "Id" column, but it
> > doesn't corrospond with the Unix PID of the process (on OS's that use
> > a seperate PID for each thread-- like Linux does)...  Is there any
> > way to(easilly) figure out which PID is handling the slave thread, so
> > that I might re-nice it after it's already been started up?
> That probably won't help you, since I doubt you're CPU-bound.  Most
> likely your slave thread is monopolizing the disk I/O.  You could try
> manually stopping and starting the thread by sending it SIGSTOP and
> SIGCONT signals.  Alternating the two every 5 seconds will give you a
> 50% slowdown.  I don't know how LinuxThreads is going to like having
> threads messes with like that though.  You can probably also do SLAVE
> STOP / SLAVE START and get the same effect.

Using SLAVE {START|STOP} is much better.  Image what happens if the
slave thread gets a critical lock and then you SIGSTOP it!

Jeremy D. Zawodny     |  Perl, Web, MySQL, Linux Magazine, Yahoo!
<Jeremy@stripped>  |
Replication priority / speedMatt Sturtz26 Dec
  • Re: Replication priority / speedJeremy Zawodny27 Dec
    • Re: Replication priority / speedMatt Sturtz30 Dec
      • Re: Replication priority / speedJeremy Zawodny30 Dec
      • Re: Replication priority / speedDan Nelson30 Dec
        • Re: Replication priority / speedJeremy Zawodny30 Dec
  • Re: Replication priority / speedSimon K. Grabowski30 Dec
    • Re: Replication priority / speedMatt Sturtz31 Dec
  • Re: Replication priority / speedSimon Grabowski1 Jan