Thanks for getting back to me Jeff, appreciate it!
It's SLES11, SP2 I believe. I suppose I'd have to consider any other modules that I've included in my configuration as well any their usage of apr_file_lock. It does seem like though, if I'm using "worker", and NFS isn't in the mix, I'd want flock to be the underlying system call used in any module using apr_file_lock. Otherwise, the locks may not be honored across threads, within a given module?
Thanks again,


From: Jeff Trawick
Sent: Wednesday, April 03, 2013 3:29 PM
To: Greg Lazar
Cc: APR Developer List
Subject: Re: Building the apr runtime library appropriately for the worker MPM

On Wed, Apr 3, 2013 at 3:03 PM, Greg Lazar <> wrote:
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.

I'm not aware of any apr_file_lock() use within httpd, so you wouldn't regress anything (unless you're using third-party modules that use apr_file_lock).  But I guess you've introduced a third-party module that uses apr_file_lock() or you wouldn't be asking about this?

I guess the apr_file_lock() use of fcntl() needs to get a thread mutex too.

What OS is this?

Born in Roswell... married an alien...