RFR: 8175891, 8192892: JrtPath improvements
Jim Laskey (Oracle)
james.laskey at oracle.com
Fri Dec 1 13:40:06 UTC 2017
+1
> On Dec 1, 2017, at 9:34 AM, Claes Redestad <claes.redestad at oracle.com> wrote:
>
> Hi,
>
> please review this patch that resolves two small but sometimes significant inefficiencies in jdk.internal.jrtfs.JrtPath:
>
> Improve JrtPath::getResolved fast-path test:
> https://bugs.openjdk.java.net/browse/JDK-8192892
>
> Testing for '.' is insufficient as it's likely all paths have a dot in them, while resolving is rare. Patch uses a test that is logically equivalent to that in ZipPath::getResolved to better filter out paths that don't need to take the slow path.
>
> JrtPath::resolve off-by-one pre-sizing cause for memory pressure:
> https://bugs.openjdk.java.net/browse/JDK-8175891
>
> As path is normalized to never end with a / this code can be simplified.
>
> Webrev: http://cr.openjdk.java.net/~redestad/8192892/open.0/
>
> In a JMH micro[1] that naively walks all entries in the JDK lib/modules and counts classes, these fixes work together to remove overhead both in repeated and single-shot settings (the latter is relevant since jrtfs usage may influence startup times in certain applications and tools):
>
> Benchmark Mode Cnt Score Error Units
> JRTWalk.walkJImage avgt 25 0.049 ± 0.003 s/op
> JRTWalk.walkJImage avgt 25 0.027 ± 0.001 s/op # 1.8x
>
> Benchmark Mode Cnt Score Error Units
> JRTWalk.walkJImage ss 20 0.436 ± 0.018 s/op (best: 0.389 s/op)
> JRTWalk.walkJImage ss 20 0.388 ± 0.017 s/op (best: 0.363 s/op)
>
> Thanks!
>
> /Claes
>
> [1] http://cr.openjdk.java.net/~redestad/8192892/JRTWalk.java
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