libxml allocates too much memory on the iphone

views:

answers:

libxml allocates too much memory on the iphone

Hello everybody,

I have a problem with the libxml parser on the iPhone! Im using the PerformXMLXPathQuery to parse a xml file with about 100'000 lines. The app breaks while running the PerformXMLPathQuery because it runs out of memory. What can I do here?

Thanks,

Markus

+1 A:

You can try to use the NSXMLParser to get only data you want to save memory usage

Benoît 2010-10-27 12:27:38

We first had NSXMLParser but this parser is way to slow for such an amount of data...

Markus 2010-10-27 12:37:39

are u sure that the problem is a problem of memory ?

Benoît 2010-10-27 12:39:46

I think so, If I run it in Instruments, the Live Bytes allocation goes up rapidly to 28.61 MB and then breaks suddenly! When look at the Device Log, the type of report is: Low Memory

Markus 2010-10-27 12:47:23

Could it be, that a special character in the xml file cause a uncontrolled Memory increase?

Markus 2010-10-27 12:48:29

+3 A:

You may want to look at libxml2's xmlTextReader "streaming" interface.

It's a foward-moving cursor that discards input data it has already processed, and doesn't build a large, memory intensive DOM as it moves forward. XPath queries can still be used, with the limitation that subtrees must be expanded (i.e., copied into in-memory libxml structures) for parts of the document that are to be searched.

The xmlTextReader interface is much more tedious than just throwing a few XPath queries at the root element, but for a document that size, on a device that's memory constrained, it may be your best bet.

I've just finished a conversion to xmlTextReader for similar reasons, and the memory used during XML processing is identical for a 20KB and 30MB document.

Mieko 2010-10-27 15:15:46

ansaurus

tags:

views:

answers:

libxml allocates too much memory on the iphone

related questions