Justin wrote:
>
> What is your key buffer size?
mysql> show variables;
ERROR 2006: MySQL server has gone away
No connection. Trying to reconnect...
Connection id: 47881
Current database: *** NO ONE ***
|
| key_buffer_size | 16773120
In my case, key buffer size is set
> to 384mb .. and mysqld starts out small, perhaps 18mb and grows
> within a day to 100mb, and within a few days to pretty much 300+mb
> ..so it is doing what one would expect it to.
Lets see:
Key Buffer (16M) + (Threads (300) * (Stack (64K) + Net Buffer( 16K))) +
Max Allow Packet (1M) + other stuff
16M * (300 * 81920) + 1M = 16M + 24M + 1M = 41M
So it isn't the thread specific storage. I'm having trouble quantifying
the maximum values for other uses of memory. Note, that typical memory
allocation when the system is busy is 41M. I'm not sure what causes the
jump to 150M+.
Note, I'm not saying this is a bug. But it is an impediment to
performance of a long running server. Also noted, this machine has 1GB
of RAM and is dedicated to MySQL. I'm not quite sure why the performance
drops off so much when the footprint gets over 150M.
>
> The other mem parameters combine in ways explained in the memory
> usage document.. so depending on those, I expect 300 threads could
> eat a lot of memory, which is not returned to the OS.
>
> -Justin
>
> On Sat, Mar 10, 2001 at 11:35:20PM -0800, Mike Wexler wrote:
> > I have a server that averages 256 queries/sec.
> > It maxes out at 1187 queries/sec.
> > It averages about 100 threads and maxes out at about 300.
> > I've never experienced the problems below with corrupted tables, but I
> > have been experiencing an interesting problem lately.
> > Normally the server uses about 20-40MB of memory as reported by top.
> > After running for a week or so, the memory usage will spike to 150-250
> > MB. Of course this causes additional paging, which slows the server
> > down, which causes the CGI scripts that talk to the server to take
> > longer to complete, which creates more instances of the CGI scripts,
> > which creates more threads, which creates more memory usage in the
> > server.
> >
> > Any idea, what might be causing the memory usage to spike in the first
> > place? Any ideas how to prevent it?
> >
> > "Jeremy D. Zawodny" wrote:
> > >
> > > On Sun, Mar 11, 2001 at 01:16:20AM -0500, Justin wrote:
> > > >
> > > > Well thats good to know.. although this is sustained 24x7x365
> > >
> > > My average rate over the last 67 days is about 52/second. In reality
> > > we have some periods of much higher load (several hundred per second)
> > > and some of much lower load. It is just about to hit the 300,000,000
> > > query mark since it was last shut down (for the upgrade 67 days ago).
> > >
> > > I'd like to hit a billion queries before the next downtime, but who
> > > knows...
> > >
> > > I'm currently running 3.23.29-gamma using the staticly linked version
> > > from mysql.com.
> > >
> > > > in an attempt to get stability, I've been running on the official
> > > > 3.22.32 mysql binary for a month now .. it hasn't helped.
> > >
> > > I'd highly recommend upgrading to 3.23.xx. You should see better
> > > performance with MyISAM tables. I'd also highly recommend using a
> > > static binary from the mysql web site.
> > >
> > > > Typically indexes get corrupted and cause selects to malfunction,
> > > > OR, cause mysqld to crash, OR cause count(*) or distinct(*) queries
> > > > to run in infinite loops, but not necessarily on the corrupt table.
> > > > it seems to me index corruption can poison the server beyond the
> > > > afflicted table.
> > >
> > > Certainly can. If a thread starts to suck cpu time, the whole system
> > > will suffer and start to spiral down into places you'd rather not
> > > look.
> > >
> > > Jeremy
> > > --
> > > Jeremy D. Zawodny, <[EMAIL PROTECTED]>
> > > Technical Yahoo - Yahoo Finance
> > > Desk: (408) 328-7878 Fax: (408) 530-5454
> > > Cell: (408) 439-9951
> > >
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> --
> Justin Beech http://www.dslreports.com
> Phone:212-269-7052 x252 FAX inbox: 212-937-3800
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>
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