Performance comparisons?

[snej]

I'm curious how parsing performance compares to other JSON parsers like

• NSJSONSerialization
• yajl
• jsonsl

It would be nice to see some timing results on realistic JSON documents.

[czechboy0]

There are performance tests in the test suite, so you could try to run those on the other parsers and compare? Let me know if you do! (I'm curious as well)

[vzsg]

I had some free time (and some insomnia), so I played around Jay and two readily available alternatives: JSONSerialization and PerfectLib. OP's other libraries are pure C with very different semantics, for which I lack both the patience and the experience to wrap for Swift.

Using sample data from here, and the benchmark classes from here, I hacked together a benchmark that loops through the parsers and the input files, parses the data 200 times, and measures the time taken by the actual JSON parsing.

Environment:

• 2015 MBP (Core i5 2.7GHz, 8 GB RAM, power adapter)
• macOS 10.12.3 Beta (16D12b)
• Swift 3.0.2 (built in release mode, default optimization settings)

Results:

Source file (size)	Library	Average time	RSD
actionLabel.json (872)	JSONSerialization	0.088701ms	35.2%
	Jay	0.27735ms	42.6%
	PerfectLib	0.192724ms	56.7%
citm_catalog.json (1727204)	JSONSerialization	10.5ms	13.0%
	Jay	195.0ms	1.7%
	PerfectLib	134.4ms	1.9%
medium.json (2202)	JSONSerialization	0.110465ms	26.9%
	Jay	0.516045ms	32.2%
	PerfectLib	0.382738ms	37.7%
menu.json (276)	JSONSerialization	0.082635ms	119.9%
	Jay	0.109255ms	24.4%
	PerfectLib	0.086137ms	107.8%
sgml.json (705)	JSONSerialization	0.078692ms	30.1%
	Jay	0.178616ms	25.3%
	PerfectLib	0.135693ms	90.1%
small.json (42)	JSONSerialization	0.077599ms	29.9%
	Jay	0.050222ms	25.5%
	PerfectLib	0.0388ms	30.7%
webxml.json (4054)	JSONSerialization	0.145353ms	26.1%
	Jay	1.006042ms	33.1%
	PerfectLib	0.755938ms	34.0%
widget.json (761)	JSONSerialization	0.114966ms	40.3%
	Jay	0.279561ms	24.0%
	PerfectLib	0.189957ms	25.9%

Takeaway:

There seems to be something very weird going on while parsing citm_catalog.json (~1,7 MBs) with both Swift libraries. That slow down is huge.

[endocrimes]

@vzsg Thanks for doing that! - I'll try and make some time for profiling this soon.