High CPU Usage?

[devicenull]

A bit of background:
I've got a windows server, running PHP 4.4.2. It hosts a few different sites, and one of them is causing high cpu usage spikes (70% utilization). Because these aren't constant, it's hard to find a way to measure them.

It's not all my code, so I don't really want to go modifying it to track down the high usage. Nor do I want to be taking sites down to determine where it came from (I will if I have to though)

Is there a way to determine which php script is causing this cpu usage?

[MarkR]

Your best bet is to have your web server measure the time taken for each request.

Then, in your development environment, running the server on a different box from the client, hit one page at once on an otherwise idle server, and repeat. That way you can get a fairly accurate idea of the time taken to generate a given page, or run a given operation.

It is important, when measuring this, that you
- Do not run client and server on the same machine
- Don't have anything else happening on the server
- Do ensure that your application is already cached in memory etc - repeat the requests and take the lowest value.

You can't make any sense out of "70% utilisation", it is a totally nonsensical statistic. In reality a CPU is always either 100% or 0% utilised. The metric you should care about is page generation time on an otherwise idle system.

Mark