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Hi Folks, I recently read an article about Facebook dumping JSON due to inadequate performance of JSON parsers. See below. I wonder how XML parsers would stack up. Do you have numbers? Parse a 20KB stream Facebook requirement: must not
exceed the UI frame refresh interval of 16.6 ms JSON parser: 35 ms to parse a JSON stream of 20 KB (a typical response size for Facebook) XML parser: ?? Parser initialization Facebook requirement: Not specified JSON parser: 100 ms to 200 ms before it can start parsing XML parser: ?? Garbage collection Facebook requirement: Not specified JSON parser: 100 KB of transient memory allocated when parsing a JSON stream of 20 KB XML parser: ??
Here’s why Facebook dumped JSON One of the key issues Facebook needed to address was how to represent and store the social graph data in
an app. Their initial approach was to store the data in JSON. They used the Jackson JSON parser on Android. However, they dumped JSON after finding these issues: Parsing speed.
It took 35 ms to parse a JSON stream of 20 KB (a typical response size for Facebook), which exceeds the UI frame refresh interval of 16.6 ms. Users were unable to load stories on demand from disk cache without observing frame drops (visual stutters) while
scrolling. Parser initialization.
A JSON parser needs to build a field mapping before it can start parsing, which can take 100 ms to 200 ms, substantially slowing down the application start time. Garbage collection.
A lot of small objects are created during JSON parsing, and testing revealed around 100 KB of transient memory was allocated when parsing a JSON stream of 20 KB, which placed significant pressure on the garbage collector. Facebook needed a better storage format to increase the performance of their Android app. What did they choose? Answer: Google FlatBuffers. /Roger |