Submission: Java 8

[topriddy]

• Time ~ 1.4 seconds
• Hardware

Processor Name: Intel Core i7
Processor Speed: 2.9GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256KB
L3 Cache: 8MB
Memory: 16GB

• External Dependencies

  • JMH (Java Microbenchmark Harness) - used for benchmarking

• Program

  • SumNumbersProgram.java - can be run standalone, replace pathName
  • BenchmarkSumNumbersProgram.java - runs the SumNumbersProgram using JMH.

• Results from JMH

Result "com.topriddy.devslack.sumnumberschallenge.BenchmarkSumNumbersProgram.init":
  1.403 ±(99.9%) 0.043 s/op [Average]
  (min, avg, max) = (1.334, 1.403, 1.564), stdev = 0.050
  CI (99.9%): [1.360, 1.446] (assumes normal distribution)


# Run complete. Total time: 00:02:03

Benchmark                        Mode  Cnt  Score   Error  Units
BenchmarkSumNumbersProgram.init  avgt   20  1.403 ± 0.043   s/op

package com.topriddy.devslack.sumnumberschallenge;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import static java.util.Arrays.asList;
import static java.util.function.Function.identity;

public class SumNumbersProgram {
    private final static String pathName = "/Users/topriddy/dev/sum-files-challenge/files";

    public void sumFiles(String dataPath) throws Exception {
        System.out.println("Starting...");
        Long startTime = System.currentTimeMillis();

        List<Path> files = Files.walk(Paths.get(dataPath))
                .filter(p -> !Files.isDirectory(p))
                .collect(Collectors.toList());

        Long sum = files.parallelStream()
                .map(path -> {
                    try {
                        return Files.lines(path);
                    } catch (IOException ioex) {
                        ioex.printStackTrace();
                        return Stream.empty();
                    }
                })
                .map(lines -> lines.map(line -> asList(((String) line).split(",")).parallelStream())
                        .flatMap(identity())
                        .map(value -> Long.valueOf(value))
                )
                .flatMap(identity())
                .mapToLong(v -> v).sum();

        Long endTime = System.currentTimeMillis();

        System.out.println("Sum of numbers in file is : " + sum);
        System.out.printf("\nDuration: %f seconds", (endTime - startTime) / 1000.0);
        System.out.println("\nEnd");
    }

    public static void main(String args[]) throws Exception {
        SumNumbersProgram program = new SumNumbersProgram();
        program.sumFiles(pathName);
        // run second time to gain JVM warm up benefit
        program.sumFiles(pathName);
    }
}

package com.topriddy.devslack.sumnumberschallenge;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Mode;

public class BenchmarkSumNumbersProgram {
    private final static String pathName = "/Users/topriddy/dev/sum-files-challenge/files";

    @Benchmark
    @BenchmarkMode(Mode.AverageTime)
    @Fork(value = 1, warmups = 1)
    public void init() throws Exception {
        SumNumbersProgram sumNumbersProgram = new SumNumbersProgram();
        sumNumbersProgram.sumFiles(pathName);
    }

    public static void main(String args[]) throws Exception {
        org.openjdk.jmh.Main.main(args);
    }
}