Looking at the output of
top I notice that intermittently there are one or two Apache processes consuming a high amount of CPU - anywhere between 50% - 90%
The spikes in CPU usage come and go quite quickly every 10 seconds or so.
There are various other Apache processes running which consume somewhere between 2% - 4%
I've researched all the various ways of trying to track down which virtualhost/website is responsible for these processes. However, because they come and go quickly I can't find a reliable way of doing this.
lsof and also looking at the output of
server-status but because the processes don't last long the process ID gets re-used and it's not possible to tie it down to the virtualhost that's causing the issue.
For example, if I run
lsof on the process ID in question, it lists a dozen different virtualhost log files which have shared that process ID in the last few seconds. I'm convinced there is one virtualhost at fault but I can't figure out which one.
I've also checked the MySQL slow query log and this doesn't reveal anything of interest.