Too many open files

I've a site on a shared host that is for the most part working well. However, more recently I've started getting the following error: failed to open stream: Too many open files in system in <filename> on line <blah>. When it happens it will happen to everyone for a short period, and then stop. There does not seem to be much if any functionality failure when that error appears (I am just seeing the error in my application logs so I can't be sure), but it is still highly annoying and worrisome. The number of files used by my application has not changed in months, however. I know PHP has a max-files-open limit somewhere. Is that per process, per user, or per server? Is this even something I can address myself in my app, or does it indicate that the server itself is getting over-busy and I have to just beg my web host for a less busy server? Any other thoughts as to how to respond? Cheers. -- Larry Garfield larry@garfieldtech.com