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jcla1/AcessBenchmark.java

Created February 6, 2014 21:31
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  1. jcla1 created this gist Feb 6, 2014.
    73 changes: 73 additions & 0 deletions AcessBenchmark.java
    View file
    Original file line number Diff line number Diff line change
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    public class AccessBenchmark {
    private final long N = 1000000000;
    private static final int M = 1;

    private LocalClass instanceVar;

    private class LocalClass {
    public void someFunc() {}
    }

    public double testInstanceVar() {
    // System.out.println("Running instance variable benchmark:");
    instanceVar = new LocalClass();

    long start = System.currentTimeMillis();
    for (int i = 0; i < N; i++) {
    instanceVar.someFunc();
    }

    long elapsed = System.currentTimeMillis() - start;

    double avg = (elapsed * 1000.0) / N;

    // System.out.println("elapsed time = " + elapsed + "ms");
    // System.out.println(avg + " microseconds per execution");

    return avg;
    }

    public double testLocalVar() {
    // System.out.println("Running local variable benchmark:");
    instanceVar = new LocalClass();
    LocalClass localVar = instanceVar;

    long start = System.currentTimeMillis();
    for (int i = 0 ; i < N; i++) {
    localVar.someFunc();
    }

    long elapsed = System.currentTimeMillis() - start;

    double avg = (elapsed * 1000.0) / N;

    // System.out.println("elapsed time = " + elapsed + "ms");
    // System.out.println(avg + " microseconds per execution");

    return avg;
    }

    public static void main(String[] args) {
    AccessBenchmark bench;

    double[] avgInstance = new double[M];
    double[] avgLocal = new double[M];

    for (int i = 0; i < M; i++) {
    bench = new AccessBenchmark();

    avgInstance[i] = bench.testInstanceVar();
    avgLocal[i] = bench.testLocalVar();

    System.gc();
    }

    double sumInstance = 0.0;
    for (double d : avgInstance) sumInstance += d;
    System.out.println("Average time for instance variable access: " + sumInstance / M);

    double sumLocal = 0.0;
    for (double d : avgLocal) sumLocal += d;
    System.out.println("Average time for local variable access: " + sumLocal / M);
    }
    }