Hello everyone!
Please help review the second version of the enhancement.
A separate branch was added to handle UTF16 in the searched string
and/or in the target and replacement.
Switching to Math.xxxExact() suggested by Tagir gave ~4% of throughput
on affected test cases.
Also, allocating uninitialized array added ~7% for Latin1 strings.
I used StringConcatHelper.newArray() to avoid bringing Unsafe into
StringLatin1.
In the StringLatin1.replace(), the newly allocated array is guaranteed
to be filled up, and the filling code should never throw, so I believe
using uninitialized arrays here is justified.
Here's the updated webrev:
http://cr.openjdk.java.net/~igerasim/8222955/01/webrev/
Below please find the benchmark numbers (with an additional column,
showing the improvement.)
Surprisingly, in one test case a slowdown was observed: Only for Latin1
string, with 1-char target, when the target string was *not* found.
If I understood it correctly, this is because prior the fix the
intrinsified StringLatin1.indexOf(byte[], byte[]) was called on the
first place, so there were effectively a fast path for exactly this pattern.
I'm not quite sure what to do about it.
Maybe this is fine as it is, since the *average* improvement across
different test cases is still good?
- prior fix:
Benchmark Mode Cnt Score Error Units
*StringReplace.replace0x1_1_Latin1 avgt 15 7.116 ± 0.060 ns/op*
StringReplace.replace0x1_1_UTF16 avgt 15 84.255 ± 3.381 ns/op
*StringReplace.replace1x1_0_Latin1 avgt 15 63.254 ± 0.973 ns/op*
StringReplace.replace1x1_0_UTF16 avgt 15 89.941 ± 3.210 ns/op
*StringReplace.replace1x1_1_Latin1 avgt 15 75.662 ± 0.344 ns/op*
StringReplace.replace1x1_1_UTF16 avgt 15 81.454 ± 1.986 ns/op
*StringReplace.replace1x1_2_Latin1 avgt 15 89.492 ± 1.889 ns/op*
StringReplace.replace1x1_2_UTF16 avgt 15 87.430 ± 1.341 ns/op
*StringReplace.replace2x1_0_Latin1 avgt 15 69.575 ± 0.368 ns/op*
StringReplace.replace2x1_0_UTF16 avgt 15 112.201 ± 2.836 ns/op
*StringReplace.replace2x1_1_Latin1 avgt 15 83.841 ± 0.940 ns/op*
StringReplace.replace2x1_1_UTF16 avgt 15 115.722 ± 2.267 ns/op
*StringReplace.replace2x1_2_Latin1 avgt 15 99.266 ± 1.008 ns/op*
StringReplace.replace2x1_2_UTF16 avgt 15 132.271 ± 2.365 ns/op
- after fix:
Benchmark Mode Cnt Score Error Units
*StringReplace.replace0x1_1_Latin1 avgt 15 10.541 ± 0.826 ns/op
x0.68*
StringReplace.replace0x1_1_UTF16 avgt 15 31.473 ± 0.389 ns/op x2.68
*StringReplace.replace1x1_0_Latin1 avgt 15 50.455 ± 5.038 ns/op
x1.25*
StringReplace.replace1x1_0_UTF16 avgt 15 35.355 ± 0.074 ns/op x2.54
*StringReplace.replace1x1_1_Latin1 avgt 15 22.868 ± 0.076 ns/op
x3.31*
StringReplace.replace1x1_1_UTF16 avgt 15 22.290 ± 1.913 ns/op x3.65
*StringReplace.replace1x1_2_Latin1 avgt 15 51.362 ± 0.130 ns/op
x1.74*
StringReplace.replace1x1_2_UTF16 avgt 15 33.086 ± 0.088 ns/op x2.64
*StringReplace.replace2x1_0_Latin1 avgt 15 57.169 ± 7.165 ns/op
x1.22*
StringReplace.replace2x1_0_UTF16 avgt 15 50.886 ± 1.193 ns/op x2.20
*StringReplace.replace2x1_1_Latin1 avgt 15 23.320 ± 2.954 ns/op
x3.60*
StringReplace.replace2x1_1_UTF16 avgt 15 24.741 ± 0.229 ns/op x4.68
*StringReplace.replace2x1_2_Latin1 avgt 15 56.045 ± 0.153 ns/op
x1.77*
StringReplace.replace2x1_2_UTF16 avgt 15 49.795 ± 0.178 ns/op x2.66
--
With kind regards,
Ivan Gerasimov
