Thanks for the advice!
I put 2.4.3ac9 (will try 2.4.4 a bit later today) on the database (and
web) servers .. However, at the peak hours and the onslaught of users
hit the site everything goes to hell ..
I'm tending to lean towards there being some issues in the MySQL area ..
During normal hours of 'low' (low being relative .. The site gets
moderate usage throughout the day) everything runs fine .. If I monitor
connections to the server (via processlist) I see lots of connections
come in .. A lot of SELECT's, a few UPDATE's, and then everything
disconnects .. And this behaviour happens throughout the day ...
However, during peak hours (9am and 5pm) the connections come in .. And
seem to overload the mysql server ... Up to 600+ connections will be in
the system .. Then mysql timeouts kick in and start killing connections
( a lot of the connections seem to be in the 'Sending data' state, or
'Locked' state because of the Updates .. ) .. Then it seems that when
the connections are killed, the clients aren't made aware of this and
just hang .. So, for example, I may see no connections in the database
(after it kills them), but yet hundreds of the scripts are still
running, not doing anything .. That may be a separate issue ..
It just seems as though MySQL (under Linux/Intel anyway) can't seem to
handle thousands of incoming connections at once .. The same behaviour
seems to happen with a bunch of scripts that just do nothing but
SELECT's (written by totally different authors) ..
Still stuck .. :-/
Thanks,
Terry
> -----Original Message-----
> From: Rene Tegel [mailto:[EMAIL PROTECTED]]
> Sent: Saturday, April 28, 2001 6:36 AM
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]
> Subject: Re: MySQL (3.23) connection bombardment question ..
>
>
> just realised it:
> another thing might be the linux threading problems. when
> spawning multiple threads at once, the 2.2 kernel will delay
> the new threads more and more. Upgrading to kernel 2.4 solves
> this. read the lists' archives on this, there were several
> discussions on this subject.
>
>
> regards,
>
> rene
>
>
> On Sat, 28 Apr 2001 10:17:26 +0000
> Rene Tegel <[EMAIL PROTECTED]> wrote:
>
> > i'm just wondering: what hangs first: your scripts or the mysql
> > database?
> >
> > if (one of your) scripts is in a endless loop, for one
> reason or the
> > other, the symptons will be the same...
> >
> > I would try to figure out if there's one particulair query
> that hangs,
> > or if it happens randomly.
> >
> > For cgi i wouldn't know what standard behaviour is when a
> client drops
> > the connection, but i guess you'll have to close the mysql
> connection
> > yourself. Do your scripts maybe exit on client
> disconnection without
> > disconnecting to the mysql server?
> >
> > Does your log say anything about connection errors?
> >
> > I'd prefer php scripts anyhow, for speed & persistant
> connections (!),
> > but it is quite tough to rewrite all scripts i'm afraid.
> >
> > gl
> >
> > rene
> >
> >
> > On Fri, 27 Apr 2001 20:45:10 -0400
> > "Terry Katz" <[EMAIL PROTECTED]> wrote:
> >
> > > Hello ..
> > >
> > > I've been experiencing a few problems with MySQL 3.23.3[67]
> > > configured for TCP on Linux ..
> > >
> > > We have two websites which are very active, and are
> noticing similar
> > > behaviour with the database.. One site has about a
> hundred thousand
> > > users, and gets very active a few times a day.. The site
> does many
> > > reads and updates to the database, at the same time .. Usually
> > > during the peak times, when it seems as though everyone
> is logging
> > > in and using it, the database starts filling up with
> queries waiting
> > > for updates to complete .. It keeps going until the
> database server
> > > (4 processors @ 550mhz ea) gets unbearably slow, and our
> cluster of
> > > webservers do the same with apache's + cgi's waiting for replies
> > > from the database ....... From what I've read, this is considered
> > > normal, because of the table locking nature of MySQL ...
> Right? Ok
> > > ..
> > >
> > > The second site does no writes to the database just
> strictly reads
> > > .. The database itself is also on a large server (4
> cpu/550mhz), and
> > > during peak times where many users bombard the site all
> at once, the
> > > database seems to act similar to above .. Connections flood the
> > > system and apache's get caught waiting for a reply ..
> > >
> > > In both cases the built-in timeouts in MySQL kill the
> connections,
> > > but the scripts (Apache's + cgi's) don't seem to get notified and
> > > just hang around indefinately ... This may be a coding bug .. (?)
> > >
> > > I guess my question is .. Are there any known problems with MySQL
> > > receiving many instantaneous connections ? (hundreds within a few
> > > seconds .. )
> > >
> > > For further info, I'm running linux 2.2.19 configured for
> up to 2000
> > > processes (the max I've seen the server get to is around 800 ..
> > > Idling at around 60)... I've tried running the database with the
> > > database both on the local raid and currently over 1gb
> ethernet to a
> > > NetApp filer (incase the local raid, which is a year or so old is
> > > too slow .. )
> > >
> > > Any ideas?
> > >
> > > Thanks,
> > > Terry Katz
> > >
> > >
> > >
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