The apr_file_lock routine, in the version of apr runtime library that I've currently built uses fnctl which does not appear to be thread safe. I need to use the worker MPM, so is it recommended that I build the apr runtime library to use flock instead. NFS file systems aren't a concern in this case. I didn't know how extensively the apr_file_lock was used through the rest of apache and if I'd be introducing any regressions by switching the apr runtime library to use flock.
 
Thank you.