CreateFile.java

package test;

import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;

import static java.nio.charset.StandardCharsets.*;

public class CreateFile {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        final String str = "あいうえおかきくけこさしすせそたちつてと\r\n";
        final int charlen = str.getBytes(UTF_8).length;

        try (BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("D:\\moreThan2G.txt"), UTF_8))) {
            long size = 0;

            while (size <= Integer.MAX_VALUE) {
                size += charlen;
                writer.write(str);
            }
        }

        try (BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("D:\\lessThan2G.txt"), UTF_8))) {
            long size = 0;

            while (size + charlen <= Integer.MAX_VALUE) {
                size += charlen;
                writer.write(str);
            }
        }
    }
}

Test.java

package test;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;

import static java.nio.charset.StandardCharsets.*;

public class Test {

    private static final String lessThan2G = "D:\\lessThan2G.txt";
    private static final String moreThan2G = "D:\\moreThan2G.txt";

    public static void main(String[] args) throws IOException {

        System.out.println("Parallel:lessThan");
        for (int i = 0; i < 10; i++) {
            measureP(lessThan2G);
        }

        System.out.println("Parallel:moreThan");
        for (int i = 0; i < 10; i++) {
            measureP(moreThan2G);
        }

        System.out.println("Single:lessThan");
        for (int i = 0; i < 10; i++) {
            measureS(lessThan2G);
        }

        System.out.println("Single:moreThan");
        for (int i = 0; i < 10; i++) {
            measureS(moreThan2G);
        }

    }

    public static void measureP(String fileName) throws IOException {
        long start = System.nanoTime();
        Files.lines(Paths.get(fileName), UTF_8).parallel().filter(s -> true).forEach(s -> {return;});
        long end = System.nanoTime();
        System.out.println((end - start) / 1000000 + "ms");

    }

    public static void measureS(String fileName) throws IOException {
        long start = System.nanoTime();
        Files.lines(Paths.get(fileName), UTF_8).filter(s -> true).forEach(s -> {return;});
        long end = System.nanoTime();
        System.out.println((end - start) / 1000000 + "ms");

    }
}

Parallel:lessThan
2891ms
2634ms
2595ms
2605ms
2540ms
2590ms
2593ms
2597ms
2549ms
2601ms
Parallel:moreThan
9371ms
9204ms
9399ms
9347ms
9112ms
9058ms
9314ms
9003ms
9138ms
9044ms
Single:lessThan
6730ms
6620ms
6666ms
6693ms
6593ms
6654ms
6678ms
6589ms
6618ms
6637ms
Single:moreThan
7116ms
7147ms
7107ms
7129ms
7107ms
7151ms
7119ms
7289ms
9998ms
8124ms

jdk-9-ea+167_windows-x64_bin.exe