On Mon, 25 Jan 2021 00:05:52 GMT, Claes Redestad <[email protected]> wrote:
> This patch optimizes the code paths exercised by
> `String.class.getResource("String.class")` by:
>
> - Adding an ASCII fast-path to methods verifying strings in the jimage, which
> can then be done allocation-free
> - Avoiding the allocation of the `long[8]` attributes when verifying only for
> the purpose of verifying a path exists
> - Using the `JNUA.create` fast-path in `SystemModuleReader` (which should be
> OK since we just verified the given name is a JRT path)
> - Remove a redundant check in `Class::resolveName` and fitting the
> `StringBuilder` to size
On the provided benchmark we can observe a 2x speed-up and a 70% reduction in
allocation.
Baseline:
Benchmark Mode Cnt
Score Error Units
ClassGetResource.stringClass avgt 5
2885.403 ± 309.787 ns/op
ClassGetResource.stringClass:·gc.alloc.rate.norm avgt 5
1368.124 ± 0.056 B/op
Patch:
Benchmark Mode Cnt
Score Error Units
ClassGetResource.stringClass avgt 5
1411.980 ± 155.877 ns/op
ClassGetResource.stringClass:·gc.alloc.rate.norm avgt 5
408.038 ± 0.043 B/op
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PR: https://git.openjdk.java.net/jdk/pull/2212
