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From "Michael H. Voase" <mvo...@midcoast.com.au>
Subject Re: Thread/Process model discussion.
Date Sat, 30 Jan 1999 11:47:45 GMT
Dean Gaudet wrote:

> On Fri, 29 Jan 1999, Rodent of Unusual Size wrote:
>
> > Dean Gaudet wrote:
> > >
> > > > The advantage to this, is that the disk I/O is going to be a killer, and
I
> > > > don't think we want multiple threads blocking on disk I/O.

>
> > >
> > > Why not?
> >
> > Because it keeps them from moving on to the next request.

>
> Somewhere you have to pay for the logging.  You can't hide it under a rug.
>
> So what if a thread doesn't move to the next request?  There are other
> threads to handle other requests.
>
> Dean

Gday ,
    I note that the topic is on threads and syslogs here so I thought
I throw in an some findings on what happens when Apache is hit
with a couple of thousand requests and syslogd craps out .

    Down here in the dungeon of the Castle we have been subjecting
Apache and mod_cgisock to numerous tortures on slow limited
hardware.This afternoon after a particularly serious
hammering I noted that Apaches response time to hits had dropped
to about 20ms with 100 clients banging away at it whilst it was
running on my krufty old 486 . Impressive thinks I untill a quick scan
of the returned info revealed that that there was no data being returned .

    Further checks revealed the situation above . once the log file had
grown to 4mb , Apache stopped serving hits but kept returning
responses which VeloMeter ( I use it cause I need  the pretty
output , on the Pentium it can give me old 486 plenty of greif :- )
interpreted as legitamate serves .

    What had happened is that syslogd , after hitting the ceiling ,
commenced restarting . After each restart it would get a request
from apache to log another line , find the log file maxxed out and
promptly restart again . All the hits were bounced but apache
never hung a single connection .

    To me , thats fair enough behavoir . Better than hanging lots
of requests until the networking layer exploded .

    Just me 2c worth anyways .

Cheers Mik Voase.

<QUICK PLUG>
PS. If youre curious about the results they're at :

    http://www.midcoast.com.au/~mvoase/cgisockperf.html

I manged to get a CGI server to serve hits faster than Apache
could serve files this afternoon . It was kruft but it beat it . Just
as an aside .... ;-)

</QUICK PLUG>

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