Re: [xml] xmlAllocOutputBuffer uses XML_BUFFER_ALLOC_EXACT

["Christopher R. Palmer" <crpalmer vivisimo com>]

Yes, that's a better patch than what I submitted and seems to work as well.

Cheers,
Chris.


----- "Daniel Veillard" <veillard redhat com> wrote:

> On Sat, Feb 21, 2009 at 09:29:49AM -0500, Christopher R. Palmer
> wrote:
> > In recent libxml2 code (I saw it when we moved from 2.6.32 to
> 2.7.2), the xmlBuffer object used by xmlAllocOutputBuffer changed from
> using the DOUBLEIT allocator to the EXACT allocator.  This ends up
> being used in xsltSaveResultToString.
> > 
> > We found that the time to save a node to a string (6MB) went from
> about 1 second to about 13 seconds on a Windows installation.
> > 
> > I've attached a tiny patch that solves the issue for us.
> 
>   Okay I think it relates to this change:
> 
> Sat Aug 30 14:50:16 CEST 2008 Daniel Veillard <daniel veillard com>
> 
>         * include/libxml/tree.h tree.c: make a new kind of buffer
> where
>           shrinking and adding in head can avoid reallocation or full
>           buffer memmoves
>         * encoding.c xmlIO.c: use the new kind of buffers for output
>           buffers
> and also
> 
> Mon Sep  1 15:02:05 CEST 2008 Daniel Veillard <daniel veillard com>
> 
>         * xmlIO.c HTMLtree.c: new internal entry point to hide even
>         * better
>           xmlAllocOutputBufferInternal
>         * tree.c: harden the code around buffer allocation schemes
> 
>  What you're seeing is at the intersection of this, where I tried to
> avoid a lot of in-memory moves in edge cases and the long identified
> but apparently still there problem of the realloc() performances on
> Windows.
>  To be sure the change to DOUBLEIT should only be done if the value
> is
> EXACT, and not any of the other values.
>  Can you check the enclosed path instead ?
> 
>   thanks,
> 
> Daniel
> 
> -- 
> Daniel Veillard      | libxml Gnome XML XSLT toolkit 
> http://xmlsoft.org/
> daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
> http://veillard.com/ | virtualization library  http://libvirt.org/

-- 
Christopher R. Palmer                     palmer vivisimo com
Chief Technology Officer                  www.vivisimo.com
Vivisimo, Inc.                            412-422-2499 ext. 118