5
  1. reader = new BufferedReader(new InputStreamReader(inputStream))
  2. reader = new InputStreamReader(new BufferedInputStream(inputStream))

which is better? why?

Improve this question
2

4 Answers 4

Reset to default
6

Never create a Reader without providing an encoding. As @CodeScale already mention, first option is better, because it leverages the BufferedReader better and it has convenience methods.

   reader = new BufferedReader(new InputStreamReader(inputStream), StandardCharsets.UTF_8);
Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

3

Solution 1 is more efficient.

The BufferedReader can have a larger buffer than InputStreamReader.

Moreover with BufferedReader you have the convenient readline method.

Improve this answer

Comments

1

Solution 1 is more efficient.

The BufferedReader will read a block of characters from the Reader (typically into a char array). read() method will return data from the internal array.

Improve this answer

1 Comment

Please don't suggest the usage of FileReader you can't provide a Charset. Use Files.newBufferedReader(Paths.get("filename"), StandardCharsets.UTF_8) instead. if you want provide a customer buffer size, you need to go with BufferedReader
1

Benchmark shows the first way (reader = new BufferedReader(new InputStreamReader(inputStream))) is far faster.

But I have no idea why.

benchmark code

package org.apache.commons.io.jmh;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URISyntaxException;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.infra.Blackhole;

@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Thread)
@Warmup(iterations = 5, time = 10, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 10, timeUnit = TimeUnit.SECONDS)
@Fork(value = 1, jvmArgs = {"-server"})
public class IOUtilsContentEqualsReadersBenchmark {
    private static final String TEST_PATH_16K_A = "/org/apache/commons/io/abitmorethan16k.txt";

    public static FileInputStream getInputStream() throws URISyntaxException, FileNotFoundException {
        return new FileInputStream(IOUtilsContentEqualsReadersBenchmark.class.getResource(TEST_PATH_16K_A).toURI().getPath());
    }

    @Benchmark
    public static void read1(Blackhole blackhole) throws Exception {
        Reader reader = new BufferedReader(new InputStreamReader(getInputStream()));
        while (true) {
            int res = reader.read();
            blackhole.consume(res);
            if (res == -1) {
                return;
            }
        }
    }

    @Benchmark
    public static void read2(Blackhole blackhole) throws Exception {
        Reader reader = new InputStreamReader(new BufferedInputStream(getInputStream()));
        while (true) {
            int res = reader.read();
            blackhole.consume(res);
            if (res == -1) {
                return;
            }
        }
    }

    @Benchmark
    public static void read3(Blackhole blackhole) throws Exception {
        Reader reader = new BufferedReader(new InputStreamReader(new BufferedInputStream(getInputStream())));
        while (true) {
            int res = reader.read();
            blackhole.consume(res);
            if (res == -1) {
                return;
            }
        }
    }
}

benchmark result

[INFO] --- exec-maven-plugin:3.0.0:exec (benchmark) @ commons-io ---
# JMH version: 1.27
# VM version: JDK 1.8.0_275, OpenJDK 64-Bit Server VM, 25.275-b01
# VM invoker: C:\jdk8u275-b01\jre\bin\java.exe
# VM options: -server
# JMH blackhole mode: full blackhole + dont-inline hint
# Warmup: 5 iterations, 10 s each
# Measurement: 5 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
# Benchmark: org.apache.commons.io.jmh.IOUtilsContentEqualsReadersBenchmark.read1

# Run progress: 0.00% complete, ETA 00:05:00
# Fork: 1 of 1
# Warmup Iteration   1: 141144.322 ns/op
# Warmup Iteration   2: 126969.546 ns/op
# Warmup Iteration   3: 117894.788 ns/op
# Warmup Iteration   4: 118555.020 ns/op
# Warmup Iteration   5: 117377.183 ns/op
Iteration   1: 118137.872 ns/op
Iteration   2: 117869.504 ns/op
Iteration   3: 117894.961 ns/op
Iteration   4: 118090.279 ns/op
Iteration   5: 117234.480 ns/op


Result "org.apache.commons.io.jmh.IOUtilsContentEqualsReadersBenchmark.read1":
  117845.419 ��(99.9%) 1390.724 ns/op [Average]
  (min, avg, max) = (117234.480, 117845.419, 118137.872), stdev = 361.167
  CI (99.9%): [116454.695, 119236.143] (assumes normal distribution)


# JMH version: 1.27
# VM version: JDK 1.8.0_275, OpenJDK 64-Bit Server VM, 25.275-b01
# VM invoker: C:\jdk8u275-b01\jre\bin\java.exe
# VM options: -server
# JMH blackhole mode: full blackhole + dont-inline hint
# Warmup: 5 iterations, 10 s each
# Measurement: 5 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
# Benchmark: org.apache.commons.io.jmh.IOUtilsContentEqualsReadersBenchmark.read2

# Run progress: 33.33% complete, ETA 00:03:20
# Fork: 1 of 1
# Warmup Iteration   1: 287001.406 ns/op
# Warmup Iteration   2: 269609.908 ns/op
# Warmup Iteration   3: 268606.597 ns/op
# Warmup Iteration   4: 259708.116 ns/op
# Warmup Iteration   5: 256359.254 ns/op
Iteration   1: 256837.341 ns/op
Iteration   2: 257773.909 ns/op
Iteration   3: 256669.369 ns/op
Iteration   4: 258031.384 ns/op
Iteration   5: 258269.111 ns/op


Result "org.apache.commons.io.jmh.IOUtilsContentEqualsReadersBenchmark.read2":
  257516.223 ��(99.9%) 2774.519 ns/op [Average]
  (min, avg, max) = (256669.369, 257516.223, 258269.111), stdev = 720.534
  CI (99.9%): [254741.704, 260290.742] (assumes normal distribution)


# JMH version: 1.27
# VM version: JDK 1.8.0_275, OpenJDK 64-Bit Server VM, 25.275-b01
# VM invoker: C:\jdk8u275-b01\jre\bin\java.exe
# VM options: -server
# JMH blackhole mode: full blackhole + dont-inline hint
# Warmup: 5 iterations, 10 s each
# Measurement: 5 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
# Benchmark: org.apache.commons.io.jmh.IOUtilsContentEqualsReadersBenchmark.read3

# Run progress: 66.67% complete, ETA 00:01:40
# Fork: 1 of 1
# Warmup Iteration   1: 146614.866 ns/op
# Warmup Iteration   2: 131029.887 ns/op
# Warmup Iteration   3: 120476.530 ns/op
# Warmup Iteration   4: 121140.296 ns/op
# Warmup Iteration   5: 119992.159 ns/op
Iteration   1: 120754.048 ns/op
Iteration   2: 120544.731 ns/op
Iteration   3: 120556.412 ns/op
Iteration   4: 120781.589 ns/op
Iteration   5: 120338.529 ns/op


Result "org.apache.commons.io.jmh.IOUtilsContentEqualsReadersBenchmark.read3":
  120595.062 ��(99.9%) 693.931 ns/op [Average]
  (min, avg, max) = (120338.529, 120595.062, 120781.589), stdev = 180.212
  CI (99.9%): [119901.131, 121288.993] (assumes normal distribution)


# Run complete. Total time: 00:05:01

REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
experiments, perform baseline and negative tests that provide experimental control, make sure
the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
Do not assume the numbers tell you what you want them to tell.

Benchmark                                   Mode  Cnt       Score      Error  Units
IOUtilsContentEqualsReadersBenchmark.read1  avgt    5  117845.419 �� 1390.724  ns/op
IOUtilsContentEqualsReadersBenchmark.read2  avgt    5  257516.223 �� 2774.519  ns/op
IOUtilsContentEqualsReadersBenchmark.read3  avgt    5  120595.062 ��  693.931  ns/op

Benchmark result is saved to target/jmh-result.org.apache.json
Improve this answer

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.