[xsd-users] in memory footprint

[Rizzuto, Raymond]

Boris,

Well, that jibes with what I saw when I took the same test code, including the mem_allocate code you sent me, and built under Window.  I was using xerces 3.0.0 there, and didn't see any 65536 byte allocations.

For now, I can live without the --generate-wildcard option since I'm only generating XML, and consuming what I generate (in debug mode only).  I'm going to look into moving to the 3.0.0 version of xerces as part of moving off sles9 and gcc 3.3.3.  It's a very old environment, and has other issues as well.

Ray

-----Original Message-----
From: Boris Kolpackov [mailto:boris at codesynthesis.com]
Sent: Friday, October 10, 2008 3:38 PM
To: Rizzuto, Raymond
Cc: xsd-users at codesynthesis.com
Subject: Re: [xsd-users] in memory footprint

Hi Ray,

Rizzuto, Raymond <Raymond.Rizzuto at sig.com> writes:

> 1) removed --generate-wildcard

Ok, this explains it. Your schema has a wildcard and when this
option is present the wildcard content is stored as a DOM fragment.
To have a DOM fragment in Xerces-C++ one needs a DOM document. To
support this each type that has one or more wildcards also contains
a DOM document in which wildcard content is stored. This document
is around even if there is no wildcard content set in the object.

I modified my test to include an optional xsd:any in each book
objects. That means that there will be total 16 DOM documents
per library object. Here is what I get with various versions
of Xerces-C++:

2.7.0:

allocate:
  count: 365
  bytes: 1064116

free:
  count: 84
  bytes: 1180


2.8.0:

allocate:
  count: 349
  bytes: 277588

free:
  count: 68
  bytes: 1020


3.0.0:

allocate:
  count: 326
  bytes: 32000

free:
  count: 68
  bytes: 1020

As you can see empty DOM documents in Xerces-C++ 2.7.0 are quite
expensive. Things got a bit better in 2.8.0 once exponential growth
of the DOM heap was implemented. Xerces-C++ 3.0.0 reduced the empty
document overhead significantly. Furthermore, Xerces-C++ 3.0.0 allows
you to tune global DOM heap allocation parameters (e.g., initial
allocation size) as well as on the per-document basis.

Boris

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