> -----Original Message-----
> From: Hyrum K Wright [mailto:hyrum_at_hyrumwright.org]
> Sent: dinsdag 15 februari 2011 11:44
> To: Greg Stein
> Cc: C. Michael Pilato; Ivan Zhakov; dev_at_subversion.apache.org
> Subject: Re: [Proposal] Remove DAV properties cache in ra_serf
>
> On Tue, Feb 15, 2011 at 6:42 AM, Greg Stein <gstein_at_gmail.com> wrote:
> > On Mon, Feb 14, 2011 at 14:14, C. Michael Pilato <cmpilato_at_collab.net>
> wrote:
> >> On 02/14/2011 01:57 PM, Ivan Zhakov wrote:
> >>> Hi,
> >>>
> >>> Currently ra_serf caches *all* DAV properties retrieved using PROPFIND
> >>> in session pool. This was attempt to reduce number of PROPFIND
> >>> requests. But current implementation has several problems:
> >>> 1. Unlimited memory usage: current implementation stores all
> >>> properties, so svn ls -R command can easily eat 150 mb of memory.
> >>> 2. Very low cache hit due the fact that cache doesn't support caching
> >>> "allprop" requests. For some operations there is no hits at all.
> >>> 3. Current implementation caches properties that may change between
> >>> requests, like URL to youngest revision.
> >>>
> >>> Of course these problems can be fixed, but I'm not sure that we need
> >>> this code. Since in svn 1.7 we have HTTPv2 which doesn't use so many
> >>> PROPFIND requests that we tried to reduce using DAV properties cache.
> >>>
> >>> So I'm propose just to remove DAV properties cache from ra_serf.
> >>> Objections? Comments?
> >>>
> >>> PS: See attached patch in case you'd like test performance.
> >>
> >> Ivan,
> >>
> >> Thanks so much for looking so closely into ra_serf recently! It hadn't
> >> occurred to me when implementing the HTTPv2 stuff that the prop cache
> might
> >> become less useful as a result.
> >>
> >> But what is the effect for older servers? Would it make sense keep the
> >> cache logic, but conditionally use it only for non-HTTPv2 connections?
> >
> > Note that removing the cache will not *break* the code. It simply
> > makes operation a bit slower.
> >
> > "upgrade your server"
> >
> > Given that we can simplify the client (remove caching), and given that
> > we can avoid unbounded memory usage, and that we don't really need the
> > cache... it seems like a win.
>
> How far can we go with this? If we're not using cached DAV properties
> with ra_serf, and ra_serf is the default in 1.7, does it make sense to
> remove support for them from the 1.7 working copy? It shouldn't be
> too difficult, and would tighten libsvn_wc up a bit.
This is about a different set of dav properties.
The working copy doesn't cache the HEAD revision for us or 'svn update'
would always be instantaneous ;-)
Bert
Received on 2011-02-15 11:47:57 CET