KAFKA-1595; remove global lock from json parser

[resetius]

No description provided.

[resetius]

This PR just removes global lock.
It can help to speed up the controller.
I recommend to use this patch together with #2213

[ijuma]

Thanks for the PR. Can you please elaborate on why it's safe to remove the global lock?

[resetius]

Previously we used a global object JSON, now we create JSON on each parseFull. I think it can be done w/o locks.

[ijuma]

Have you measured the cost of creating a new parser each time? A change like this requires a few benchmarks to motivate it.

[resetius]

Reasonable. I'll try to do some benchmarks.

[resetius]

I got a strange memleak inside new JSON. Now I use ThreadLocal and assume that kafka uses constant number of threads. But of course a better solution is to use some modern json parser like json4s.

[asfbot]

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Test FAILed (JDK 8 and Scala 2.11).

[asfbot]

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Test PASSed (JDK 8 and Scala 2.12).

[asfbot]

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Test PASSed (JDK 7 and Scala 2.10).