mod_dav_fs performances

[Emmanuel Dreyfus <ma...@netbsd.org>]

Hello

I have been badly hit by a performance problem in mod_dav_fs. After a
few users updated to (RaiDrive/2022.6.56.0), all users reported terrible
performance, with files taking age to open.

Investigating the problem, we discovered lock contention of the DavLockDB 
file. Too many clients looking up locks, too often. A log analysis show
that RaiDrive/2022.6.56.0 does much more PROPFIND than other clients.
PROPFIND involves lock discovery, and lock discovery needs serialized
access to DavLockDB.

I submitted a proposed fix in 
https://bz.apache.org/bugzilla/show_bug.cgi?id=66313 I 

This introduces a DAVLockDiscovery option to optionaly disable lock
discovery. It uses an apache expession so that the thing can be fine
tuned, e.g. disabling it for specific UserAgent that exhibit an abusive
behavior.

When lock discovery is disabled, PROPFIND just returns an empty lock
discovery section.

I have been testing disabling lock discovery for a week, it works well. 
Performances are good again, and no regression appeared.

-- 
Emmanuel Dreyfus
manu@netbsd.org

Re: mod_dav_fs performances

[Yann Ylavic <yl...@gmail.com>]

On Mon, Oct 17, 2022 at 9:20 AM Emmanuel Dreyfus <ma...@netbsd.org> wrote:
>
> I submitted a proposed fix in
> https://bz.apache.org/bugzilla/show_bug.cgi?id=66313 I

Thanks for this, checked in trunk (r1904638).


Regards;
Yann.