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From:Philipp Date:March 19 2003 10:02am
Subject:Re: Process Limit on Linux ?
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Hi Joseph,

thank you for your answer. While i was reading
about clustering some weeks ago i read the openmosix
FAQ claiming that openmosix would not work with apache,
because apache was using shared memory to communicate
with its threads, and i always thought mysql is designed
the same way. Please someone correct me if i am wrong.

Regards,
Philipp


On Wed, 19 Mar 2003 10:41:21 +0100
Joseph Bueno <joseph.bueno@stripped> wrote:

> Hi,
> 
> Since shm (shared memory) in Unix/Linux is only used to share memory
> between independent processes and mysql server is a single process
> (multi-threaded), I am convinced that shmmax value has no consequence
> on mysql. (OTOH Oracle has a multiprocess architecture and uses
> shared memory).
> 
> Hope this helps,
> Joseph Bueno
> 
> Philipp wrote:
> > Dear Walt, dear List,
> > 
> > 
> > thank you for your reply. Finally a suggestions at all.
> > I checked both
> > 
> > /proc/sys/kernel/threads-max
> > /proc/sys/kernel/shmmax
> > 
> > I dont think threads-max will be a problem, because the value is 14336,
> > and i dont think my system will ever have to handle this number of threads.
> > 
> > But researching shmmax at google i got several hits. Most are dealing with
> > postgres but perhaps its the same with mysql.
> > 
> > shmmax ist 32 MB. on one page the author suggest to raise this value to 128
> > MB.
> > 
> > What are your suggestions for the values:
> > 
> > shmall  shmmax  shmmni ?
> > 
> > 
> > Thank you very much,
> > Yours Philipp
> > 
> > ----- Original Message -----
> > From: "walt" <kernel@stripped>
> > To: "Philipp" <kernel@stripped>
> > Cc: <mysql@stripped>
> > Sent: Monday, March 17, 2003 6:48 PM
> > Subject: Re: Process Limit on Linux ?
> > 
> > 
> > 
> >>Philipp wrote:
> >>
> >>>Hi there,
> >>>
> >>>i wrote several times to the list asking for help with a problem
> >>>regarding process limits on linux, but never got an answer.
> >>>today i found this story:
> >>>
> >>>http://www.mysql.com/press/user_stories/handy.de.html
> >>>
> >>>here are the relevant sentences:
> >>>
> >>>"We had some process limit problems on our Linux Systems,
> >>>but thanks to your support we where able to patch the linux boxes
> >>>and move the limit to a size that meets our needs (we've got an average
> > 
> > of
> > 
> >>>about
> >>>1600 concurrent threads per server)."
> >>>
> >>>These people use 2.2 Kernels so i dont know if the mentioned kernel and
> >>>glibc
> >>>patching is also relevant for me, as i am using 2.4 kernels only.
> >>>
> >>>Here is my problem in detail:
> >>>
> >>>i am using mysql-3.23.55 binary packages on linux 2.4.20 and i raised
> > 
> > ulimit
> > 
> >>>values and configuration in my.conf to allow more then 1500 threads. but
> >>>when
> >>>there are around 750 threads a new client connecting is told something
> > 
> > like
> > 
> >>>that (dont have the errno at the moment, i think its 11):
> >>>
> >>>"cant create new thread, perhaps you are out of memory or there is a
> >>>os-depended bug".
> >>>
> >>>The machine only runs apache and mysql and is a Xeon 2x2 2.4 Gz with 2
> > 
> > GB of
> > 
> >>>RAM.
> >>>cat /proc/meminfo sais that more then 1 Gig is used for caching, so
> > 
> > memory
> > 
> >>>should be no
> >>>problem .
> >>>
> >>>Please, if you have any ideas, let me know. If it is a kernel issue,
> > 
> > tell me
> > 
> >>>to go to linux mailing lists
> >>>or if its some kind of "secret issue" only the support will be able to
> >>>answer let me know that.
> >>>
> >>>Thanks in advance,
> >>>Philipp
> >>>
> >>>---------------------------------------------------------------------
> >>>Before posting, please check:
> >>>   http://www.mysql.com/manual.php   (the manual)
> >>>   http://lists.mysql.com/           (the list archive)
> >>>
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> > 
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> > 
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> >>
> >>Philipp,
> >>Did you check /proc/sys/kernel/threads-max? I know with oracle 8i, you
> >>are supposed to increase  /proc/sys/kernel/shmmax as well as some other
> >>values. You might check into that and see if changing those values will
> >>help.
> >>Does your syslog say anything when these problems occur?
> >>
> >>walt
> >>
> >>walt
> >>
> > 
> 
> 


-- 


-----------------
Philipp Steinkrueger
Oberberg Online Informationssysteme GmbH
Technik
http://www.oberberg.net

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Thread
Process Limit on Linux ?Philipp16 Mar
  • Re: Process Limit on Linux ?walt17 Mar
  • Re: Process Limit on Linux ?Philipp18 Mar
    • Re: Process Limit on Linux ?Joseph Bueno19 Mar
      • Re: Process Limit on Linux ?Philipp19 Mar
        • Re: Process Limit on Linux ?Dan Nelson19 Mar
          • Re: Process Limit on Linux ?Philipp19 Mar
            • Re: Process Limit on Linux ?Joseph Bueno19 Mar
            • Re: Process Limit on Linux ?Dan Nelson19 Mar
              • Re: Process Limit on Linux ?walt19 Mar
  • Re: Process Limit on Linux ?Philipp18 Mar