On Mon, 12 Apr 2021 02:40:27 GMT, Yi Yang <yy...@openjdk.org> wrote: >> Hello, >> >> to avoid cases detected in >> [https://github.com/openjdk/jdk/pull/2992](https://github.com/openjdk/jdk/pull/2992) >> I propose to modify JavaDoc of `ByteArray*Stream` to explicitly mention >> redundancy of wrapping with `BufferedInputStream`. >> >> As of `InputStream` I think in notation `It is never correct to use the >> return value of this method to allocate a buffer intended to hold all data >> in this stream.` the word 'never' should be replaced with 'usually': apart >> from `ByteArrayInputStream` e.g. `FileInputStream.available()` often returns >> the count of remaining bytes (the only exclusion I'm aware of is the files >> located under `/proc/`) and indeed this count can be used to allocate a >> buffer to read all the bytes in one call. >> >> Consider benchmark >> >> >> @BenchmarkMode(Mode.AverageTime) >> @OutputTimeUnit(TimeUnit.NANOSECONDS) >> public class ByteArrayInputStreamBenchmark { >> >> @Benchmark >> public void read(Data data, Blackhole bh) { >> int value; >> var in = data.bais; >> while ((value = in.read()) != -1) { >> bh.consume(value); >> } >> } >> >> @Benchmark >> public void readBuffered(Data data, Blackhole bh) throws IOException { >> int value; >> var in = new BufferedInputStream(data.bais); >> while ((value = in.read()) != -1) { >> bh.consume(value); >> } >> } >> >> @Benchmark >> public Object readAllBytes(Data data) { >> var in = data.bais; >> return in.readAllBytes(); >> } >> >> @Benchmark >> public Object readAllBytesBuffered(Data data) throws IOException { >> var in = data.bais; >> return new BufferedInputStream(in).readAllBytes(); >> } >> >> @State(Scope.Thread) >> public static class Data { >> >> @Param({"8", "128", "512", "1024"}) >> private int length; >> >> private byte[] bytes; >> private ByteArrayInputStream bais; >> >> @Setup(Level.Iteration) >> public void setUp() { >> bytes = new byte[length]; >> ThreadLocalRandom.current().nextBytes(bytes); >> } >> >> @Setup(Level.Invocation) >> public void setUpBais() { >> bais = new ByteArrayInputStream(bytes); >> } >> } >> } >> >> >> giving >> >> >> (length) Score Error >> Units >> read 8 55.737 ± 0.431 >> ns/op >> read 128 533.172 ± 1.613 >> ns/op >> read 512 2066.238 ± 23.989 >> ns/op >> read 1024 4335.570 ± 20.137 >> ns/op >> >> readBuffered 8 521.936 ± 2.454 >> ns/op >> readBuffered 128 971.617 ± 100.469 >> ns/op >> readBuffered 512 2284.472 ± 251.390 >> ns/op >> readBuffered 1024 4168.598 ± 77.980 >> ns/op >> >> readAllBytes 8 34.850 ± 0.072 >> ns/op >> readAllBytes 128 36.751 ± 0.133 >> ns/op >> readAllBytes 512 45.304 ± 0.699 >> ns/op >> readAllBytes 1024 61.790 ± 0.386 >> ns/op >> >> readAllBytesBuffered 8 870.454 ± 4.406 >> ns/op >> readAllBytesBuffered 128 910.176 ± 32.258 >> ns/op >> readAllBytesBuffered 512 896.155 ± 6.005 >> ns/op >> readAllBytesBuffered 1024 965.596 ± 29.225 >> ns/op >> >> read:·gc.alloc.rate.norm 8 32.006 ± 0.001 >> B/op >> read:·gc.alloc.rate.norm 128 32.007 ± 0.004 >> B/op >> read:·gc.alloc.rate.norm 512 32.010 ± 0.010 >> B/op >> read:·gc.alloc.rate.norm 1024 32.011 ± 0.008 >> B/op >> >> readBuffered:·gc.alloc.rate.norm 8 8280.354 ± 0.016 >> B/op >> readBuffered:·gc.alloc.rate.norm 128 8240.484 ± 0.015 >> B/op >> readBuffered:·gc.alloc.rate.norm 512 8240.599 ± 0.056 >> B/op >> readBuffered:·gc.alloc.rate.norm 1024 8280.978 ± 0.024 >> B/op >> >> readAllBytes:·gc.alloc.rate.norm 8 56.008 ± 0.001 >> B/op >> readAllBytes:·gc.alloc.rate.norm 128 176.017 ± 0.001 >> B/op >> readAllBytes:·gc.alloc.rate.norm 512 560.035 ± 0.002 >> B/op >> readAllBytes:·gc.alloc.rate.norm 1024 1072.057 ± 0.002 >> B/op >> >> readAllBytesBuffered:·gc.alloc.rate.norm 8 16512.660 ± 0.026 >> B/op >> readAllBytesBuffered:·gc.alloc.rate.norm 128 16632.684 ± 0.008 >> B/op >> readAllBytesBuffered:·gc.alloc.rate.norm 512 17016.694 ± 0.017 >> B/op >> readAllBytesBuffered:·gc.alloc.rate.norm 1024 17528.748 ± 0.012 >> B/op > > Hi, I create the issue https://bugs.openjdk.java.net/browse/JDK-8265039 for > this PR🚀.
@kelthuzadx thanks! ------------- PR: https://git.openjdk.java.net/jdk/pull/3341
