Example PerfRunner test that compares file writing performance under a variable number of concurrent threads.

MultiThreadWrite.java

  @Test
  public void perThread(@Varying(name = "thread", axis = Axis.X, from = 1, to = 10, step = 1) final int threadCount) throws Exception {

    // First define the task that needs to be done.
    // This task writes a million 'a' characters to a file:
    Runnable task = new Runnable() {
      @Override
      public void run() {

        // create temporary file with extension suffix
        File file1 = File.createTempFile("PerThreadTest", ".javatemp");
        BufferedWriter out = new BufferedWriter(new FileWriter(file1));

        int megabyte = 1000000;
        for (int i = 1; i < megabyte; i++) {
          out.write('a');
        }
        out.close();
      }
    };

    // Now define the executor service that will execute the above task
    ExecutorService exec = Executors.newFixedThreadPool(threadCount);

    // Submit the task 10 times (total data written will be 10MB)
    for (int i = 0; i < 10; i++) {
      exec.submit(task);
    }

    // Finally, wait for all the submitted tasks to complete (1 hour should be way more than enough!)
    exec.awaitTermination(1, TimeUnit.HOURS);

    // Free the threads that were created by Executors.newFixedThreadPool(threadCount) above
    exec.shutdown();
  }