@interface AQBlog : NSBlog @end

Tutorials, musings on programming and ePublishing

AQXMLParser == Big Memory Win

Permalink

I just wrote an AQXMLParser test project, along with a Ruby script which generated a 22MB XML file looking kinda like this:

<root>
<level1 id="levelOne">
<level2 id="levelTwo">
<number>0</number>
</level2>
</level1>
<level1 id="levelOne">
<level2 id="levelTwo">
<number>1</number>
</level2>
</level1>
</root>

…except with 200'000 items. I then record the amount of virtual memory used by the app each time it parses a 'number' item, keeping track of the peak amount allocated on top of the vm usage just before the parser launched (so measures only the memory allocated from calling [parser parse] and anything internal to that routine). This means that even the 22MB for the XML data isn't included in the output here.

Here's the output. I think it shows that AQXMLParser is going to be lovely for the iPhone. Mwa-ha-haa.

Testing NSXMLParser from URL...
Parsed 200000 numbers
Peak VM usage: 128991232 bytes
Testing NSXMLParser with mapped data...
Parsed 200000 numbers
Peak VM usage: 130035712 bytes
Testing AQXMLParser...
Parsed 200000 numbers
Peak VM usage: 69632 bytes

That's right, the NSXMLParser variant (calling xmlParseChunk() with all data at once) uses 123-124MB, while AQXMLParser (calling xmlParseChunk() with 1KB at a time, not loading all data anywhere) gets 68KB.

In short: AQXMLParser == T3h w1n!

Code is on github now.

Comments