How to solve the XML parsing performance issue on Android
I have to read a XML file with about ~4000 lines on Android. First I tried the SimpleXML library because it's the easiest and it took about 2 minutes on my HTC Desire. So I thought maybe SimpleXML is so slow because of reflection and all the other magic that this library uses. I rewrote my parser and used the built-in DOM parsing method with some special attention for performance. That helped a bit but it still took about 60 seconds which is still totally unacceptable. After a bit of research I found this article on developer.com. There are some graphs that show that the other two available methods - the SAX parser and Android's XML Pull-Parser - are equally slow. And at the end of the article you'll find the following statement:
The first surprise I had was at how slow all three methods were. Users don't want to wait long for results on mobile phones, so parsing anything more than a few dozen records may mandate a different method.
What might be a "different method"? What to do if you have more than "a few dozen records"?
Answer
Original answer, in 2012
(note: make sure you read the 2016 update below!)
I just did some perf testing comparing parsers on Android (and other platforms). The XML file being parsed is only 500 lines or so (its a Twitter search Atom feed), but Pull and DOM parsing can churn through about 5 such documents a second on a Samsung Galaxy S2 or Motorola Xoom2. SimpleXML (pink in the chart) as used by the OP ties for slowest with DOM parsing.
SAX Parsing is an order of magnitude faster on both of my Android devices, managing 40 docs/sec single-threaded, and 65+/sec multi-threaded.
Android 2.3.4:
The code is available in github, and a discussion here.
Update 18th March 2016
OK, so its been almost 4 years and the world has moved on. I finally got around to re-running the tests on:
- A Samsung Galaxy S3 running Android 4.1.2
- A Nexus7 (2012) running Android 4.4.4
- A Nexus5 running Android 6.0.1
Somewhere between Android 4.4.4 and Android 6.0.1 the situation changed drastically and we have a new winner: Pull Parsing FTW at more than twice the throughput of SAX. Unfortunately I don't know exactly when this change arrived as I don't have any devices running Android > 4.4.4 and < 6.0.1.
Android 4.1.2:
Android 4.4.4:
Android 6.0.1:
