RFR: 8280010: Remove double buffering of InputStream for Properties.load

[Andrey Turbanov]

On Mon, 10 Jan 2022 20:46:36 GMT, Andrey Turbanov <duke at openjdk.java.net> wrote:

> `Properties.load` uses `java.util.Properties.LineReader`. LineReader already buffers input stream. Hence wrapping InputStream in BufferedInputStream is redundant.

Checked. `BufferedInputStream` add a bit of overhead.

Benchmark

@BenchmarkMode(value = Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 6, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Fork(1)
@State(Scope.Benchmark)
public class PropertiesLoad {

    Properties properties;
    private InputStream arrayInputStream;
    private InputStream fileInputStream;
    private Path filePath;

    @Setup
    public void setupStrings() throws IOException {
        properties = new Properties();
        String content = """
                currentVersion=IdealGraphVisualizer {0}
                LBL_splash_window_title=Starting IdealGraphVisualizer
                SPLASH_WIDTH=475
                SplashProgressBarBounds=0,273,475,6
                SplashProgressBarColor=0xFFFFFF
                SplashRunningTextBounds=10,283,460,12
                SplashRunningTextColor=0xFFFFFF
                """;
        filePath = Files.createTempFile("benchmark", ".properties");
        Files.writeString(filePath, content);
        arrayInputStream = new ByteArrayInputStream(content.getBytes(StandardCharsets.UTF_8));
        fileInputStream = Files.newInputStream(filePath);
    }

    @TearDown
    public void tearDown() throws IOException {
        fileInputStream.close();
        Files.delete(filePath);
    }

    @Benchmark
    public Properties plain_ByteStream() throws IOException {
        properties.load(arrayInputStream);
        return properties;
    }

    @Benchmark
    public Properties plain_fileStream() throws IOException {
        properties.load(fileInputStream);
        return properties;
    }

    @Benchmark
    public Properties buffered_ByteStream() throws IOException {
        properties.load(new BufferedInputStream(arrayInputStream));
        return properties;
    }

    @Benchmark
    public Properties buffered_fileStream() throws IOException {
        properties.load(new BufferedInputStream(fileInputStream));
        return properties;
    }

    public static void main(String[] args) throws RunnerException {
        Options opt = new OptionsBuilder()
                .include(PropertiesLoad.class.getSimpleName())
                .build();

        new Runner(opt).run();
    }
}

Results:

Benchmark                           Mode  Cnt     Score     Error  Units
PropertiesLoad.buffered_ByteStream  avgt    5  2416,364 ±  46,209  ns/op
PropertiesLoad.buffered_fileStream  avgt    5  4276,015 ± 139,094  ns/op
PropertiesLoad.plain_ByteStream     avgt    5  1445,864 ± 649,779  ns/op
PropertiesLoad.plain_fileStream     avgt    5  3183,012 ± 198,974  ns/op

-------------

PR: https://git.openjdk.java.net/jdk/pull/7021