I've got several entries like this in my error log, and every time I've got one, the apache initiated a graceful restart:
Permission denied: mod_rewrite: failed to unlock file descriptor
Resource deadlock avoided: mod_rewrite: failed to lock file descriptor
I've checked some resources about this, but the most I could find about this, is that if I use external rewriting then I need to configure the lock file for mod_rewrite to work properly, but all I use is simple rewriting (although it is complicated), without using a single RewriteMap...
I have several problems with this box, like when I initiate a graceful restart the old apache child remains running for a loooong time and uses half of the cpu cycles, and if I restart it twice within one minute for example, then it consumes all the cpu time... Did I mentioned, that the machine has two xeon processors?