On Thu, Jan 25, 2007 at 12:07:23PM +0000, Niall O Broin wrote:
> There is no clue in neither the access nor error logs. The other
> server on the box, which is the same version of apache, never does this.
This almost always turns out to be a dynamic scripting module, usually
mod_php and a blocking operation in some code chewing up the process.
The most recent spate of these is down to a single wordpress plugin,
Spam Karma, which when an RBL maintainer deleted the RBL suddenly caused
all word-press comments to create hanging blocking DNS requests which
the PHP code did not handle properly at all.
The best thing to do is to attach gdb to the process and to do a
backtrace and see what functions it's blocking in. You can use tools
like lsof/fuser and strace/truss to see any blocking file descriptors
and system calls too.
In apache 2.x, mod_forensic_log is a good way of isolating the
requests that actually cause the problems.
Colm MacCárthaigh Public Key: colm+pgp at stdlib.net
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