On Wed, 5 May 2021 17:10:13 GMT, Brian Burkhalter <b...@openjdk.org> wrote:
>> Please consider this request to override the `java.io.InputStream` methods >> `readAllBytes()` and `readNBytes(int)` in `FileInputStream` with more >> performant implementations. The method overrides attempt to read all >> requested bytes into a single array of the required size rather than >> composing the result from a sequence of smaller arrays. An example of the >> performance improvements is as follows. >> >> **readAllBytes** >> Before >> >> Benchmark (length) Mode Cnt Score >> Error Units >> ReadAllBytes.readAllBytesFileInputStream 1000000 thrpt 20 2412.031 >> ± 7.309 ops/s >> ReadAllBytes.readAllBytesFileInputStream 10000000 thrpt 20 212.181 >> ± 0.369 ops/s >> ReadAllBytes.readAllBytesFileInputStream 100000000 thrpt 20 19.860 >> ± 0.048 ops/s >> ReadAllBytes.readAllBytesFileInputStream 1000000000 thrpt 20 1.298 >> ± 0.183 ops/s >> >> After >> >> Benchmark (length) Mode Cnt Score >> Error Units >> ReadAllBytes.readAllBytesFileInputStream 1000000 thrpt 20 8218.473 >> ± 43.425 ops/s >> ReadAllBytes.readAllBytesFileInputStream 10000000 thrpt 20 302.781 >> ± 1.273 ops/s >> ReadAllBytes.readAllBytesFileInputStream 100000000 thrpt 20 22.461 >> ± 0.084 ops/s >> ReadAllBytes.readAllBytesFileInputStream 1000000000 thrpt 20 1.502 >> ± 0.003 ops/s >> >> >> **readNBytes** >> >> `N = file_size / 2` >> >> Before >> >> Benchmark (length) Mode Cnt Score >> Error Units >> ReadAllBytes.readHalfBytesFileInputStream 1000000 thrpt 20 5585.500 >> ± 153.353 ops/s >> ReadAllBytes.readHalfBytesFileInputStream 10000000 thrpt 20 436.164 >> ± 1.104 ops/s >> ReadAllBytes.readHalfBytesFileInputStream 100000000 thrpt 20 40.167 >> ± 0.141 ops/s >> ReadAllBytes.readHalfBytesFileInputStream 1000000000 thrpt 20 3.291 >> ± 0.211 ops/s >> >> >> After >> >> Benchmark (length) Mode Cnt Score >> Error Units >> ReadAllBytes.readHalfBytesFileInputStream 1000000 thrpt 20 15463.210 >> ± 66.045 ops/s >> ReadAllBytes.readHalfBytesFileInputStream 10000000 thrpt 20 561.752 >> ± 0.951 ops/s >> ReadAllBytes.readHalfBytesFileInputStream 100000000 thrpt 20 45.043 >> ± 0.102 ops/s >> ReadAllBytes.readHalfBytesFileInputStream 1000000000 thrpt 20 4.629 >> ± 0.035 ops/s > > Brian Burkhalter has updated the pull request incrementally with one > additional commit since the last revision: > > 8264777: Fix typo in error message src/java.base/share/classes/java/io/FileInputStream.java line 289: > 287: } > 288: if (size <= 0L) > 289: return new byte[0]; Maybe the case where size <= 0L should also default to `return super.readAllBytes()`? ------------- PR: https://git.openjdk.java.net/jdk/pull/3845
