On Tue, 4 May 2021 14:07:18 GMT, Alan Bateman <al...@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 > > src/java.base/share/classes/java/io/FileInputStream.java line 342: > >> 340: >> 341: private native long length() throws IOException; >> 342: private native long position() throws IOException; > > Can you confirm that you've tested with special files? It's very likely that > there will be cases where lseek will fail. Only regular files this far. Are there any particular special files which would be of interest? ------------- PR: https://git.openjdk.java.net/jdk/pull/3845
