Review request for JDK-8062141: Various performance issues parsing JSON

[Marcus Lagergren]

+1!

Nicely done.

> On 04 Feb 2015, at 13:49, Hannes Wallnoefer <hannes.wallnoefer at oracle.com> wrote:
> 
> I uploaded a new wevrev:
> 
> http://cr.openjdk.java.net/~hannesw/8062141/webrev.02/
> 
> This version builds the property maps and value containers directly in the JSON parser, making use of PropertyMap's history feature to reuse maps.
> 
> Answers to Marcus' questions are inline below.
> 
> Am 2015-01-31 um 16:40 schrieb Marcus Lagergren:
>> Awesome numbers, Hannes. Why was the last JSON parser so slow? I guess it was just a case of clean room implement per spec to ensure correctness, right? I don’t think we’ve paid a lot of attention to the JSON code since it was first written.
> 
> I couldn't find a single issue with the old parser, so it's more like a death from thousand cuts. There's certainly room for improvement, which is important as these are the same base classes used by our main parser.
>> 
>> Does everything compile without warnings? I notice you have explicitly added a @SuppressWarnings(“unchecked”) in JSONFunctions. Why was this the case? List<?> still too weak?
> You're right, that @SuppressWarnings was not needed. In any case I removed the code that used it in my rewrite :)
> 
>> Do your ProperyHashMap changes give us benefits in performance elsewhere too? (or slowdowns for that matter)
> I did these changes while working on the JSONParser and they seemed to help. However, to be sure I wrote a PropertyHashMap microbenchmark and what I found is that while these changes make creation of PropertyHashMap slightly faster, they slightly slow down access of properties. Since the latter is probably more important in a longer running process I removed those changes from my new webrev.
> 
>> Do you have any micro benchmarks you used to test this to check in ?
> 
> I added one, it's in test/examples/json-parser-micro.js
> 
> Hannes
> 
>> 
>> +1
>> 
>> /M
>> 
>>> On 30 Jan 2015, at 17:40, Hannes Wallnoefer<hannes.wallnoefer at oracle.com>  wrote
>>> 
>>> Please review JDK-8062141: Various performance issues parsing JSON:
>>> 
>>> http://cr.openjdk.java.net/~hannesw/8062141/
>>> 
>>> Thew new JSON parser is about 2-3 x faster than our old one, roughly on par with the ones in Rhino or V8.
>>> 
>>> Hannes
>