[ILUG] Hanging apache

[Niall O Broin]

On 25 Jan 2007, at 12:19, Colm MacCarthaigh wrote:

> 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.

This is very likely to be the answer, as the site is based on some  
awfully cruddy PHP. But I'm a little puzzled as to why this hangs the  
server completely. It only happens sometimes, so should it not then  
only block one child? Or perhaps what happens is that this is a  
gradual process, which hangs child after child until the entire  
allowed number of children has been spawned and is hanging.

> 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.

I suspect this won't help very much - it's going to show me there's a  
problem in mod_php, I'll be bound. But I'll give it a whirl - it may  
well be that it'll narrow it down a little more than that.

> In apache 2.x, mod_forensic_log is a good way of isolating the
> requests that actually cause the problems.

OK - so I'll have more tools at my disposal when we move it to apache  
2 - that's good to know.

Thanks Colm,


Niall