Messages in this thread | | | Date | Thu, 6 May 1999 12:43:28 -0400 (EDT) | From | Phillip Ezolt <> | Subject | Re: Overscheduling DOES happen with high web server load. |
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Dean, > As shipped, apache-1.3.6 on linux uses fcntl() file locking to prevent > more than one process from being inside accept(). I'm not sure if the dec > folks have rebuilt the server with -DSINGLE_LISTEN_UNSERIALIZED_ACCEPT... > if they have, then there's no protection around accept() in servers > listening on a single port.
Apache was built with the following flags: (-DSINGLE_LIST_UNSERIALIZED_ACCEPT is not amoung them. )
./configure --prefix=/usr --libexecdir=/usr/lib/apache --sysconfdir=/etc/httpd/conf --datadir=/home/httpd --includedir=/usr/include/apache --logfiledir=/var/log/httpd --localstatedir=/var --runtimedir=/var/run --proxycachedir=/var/cache/httpd --enable-m odule=all --enable-shared=max --disable-rule=WANTHSREGEX
Would it be better to build with -DSINGLE_LISTEN_UNSERIALIZED_ACCEPT? Is this something that would help or hurt the "thundering herd" problem?
--Phil
Digital/Compaq: HPSD/Benchmark Performance Engineering Phillip.Ezolt@compaq.com ezolt@perf.zko.dec.com
On Thu, 6 May 1999, Dean Gaudet wrote:
> As shipped, apache-1.3.6 on linux uses fcntl() file locking to prevent > more than one process from being inside accept(). I'm not sure if the dec > folks have rebuilt the server with -DSINGLE_LISTEN_UNSERIALIZED_ACCEPT... > if they have, then there's no protection around accept() in servers > listening on a single port. > > At any rate, for apache 1.3.x we require some form of locking (fcntl() in > linux' case) when there are multiple listening sockets... so you also need > to solve the thundering herd problem for fcntl() if it has one. > > Last time I brought up wake-on accept(), Alan said it is a hard problem. > Maybe wake-one fcntl() is easier. > > Dean > > >
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