Bazaar on the iPod Touch.

[Martin Pool]

On 08/01/2008, Andrew Cowie <andrew at operationaldynamics.com> wrote:

> [For what it's worth, and based solely on experience in the Java world
> and to a lesser extent on experience in GNOME land],
>
> XML handling has proved to be _incredibly_ computationally expensive.
> While XML can be lovely to conceptually express data in, serializing an
> object graph to and from XML, parsing text into a DOM (or whatever)
> model, and then the impact of keeping it all in memory to manipulate has
> been quite significant.

That's been our experience too.  Also, having decent libraries to work
with it may add another dependency -- cElementTree for us (on 2.4) and
now this on the iPhone.

> Usually, XML is either non-optional or worth the cost, but I suppose I
> am moved to ask the Bazaar hackers about their use of XML and whether it
> might be a pressure point from a performance perspective? I was a bit
> surprised at what Alexander noted above.

It is a pressure point.  John and others have profiled it; it is not
the dominant factor for most operations but it would be good to remove
it.  (10-20% of time iirc.)  Robert's new format, for instance, does
not use xml for inventories.

-- 
Martin