Thank you Fengbin Fang for doing this microbenchmark!
The numbers clearly show that your approach is a lot faster.
I'm curious if this does also affect the performance of a complete data
flow.
Looking forward to your results,
Fabian
2015-08-13 8:35 GMT+02:00 Fangfengbin <fangfeng...@huawei.com>:
> Hello!
>
> I have a test about cost of System.currentTimeMillis() and my
> CLOCK.currentTimeMillis() .( My clock will be a JVM singleton)
> Call currentTimeMillis function 100000000 times,
> System.currentTimeMillis() need about 1902ms and my
> CLOCK.currentTimeMillis() only need 119ms.
> The function performance is up to about 15 times.
> Next I will use a streaming job to test it.
>
> This is my code:
> #########
> class MillisecondClock {
> private long rate = 0;
> private volatile long now = 0;
>
> private volatile boolean isRunning = true;
>
> private MillisecondClock(long rate) {
> this.rate = rate;
> this.now = System.currentTimeMillis();
> start();
> }
>
> private void start() {
> new Thread(new Runnable() {
> @Override
> public void run() {
> while(isRunning)
> {
> try {
> Thread.sleep(rate);
> } catch (InterruptedException e) {
> e.printStackTrace();
> }
> now = System.currentTimeMillis();
> }
>
> }
> }).start();
> }
>
> public long currentTimeMillis() {
> return now;
> }
>
> public static final MillisecondClock CLOCK = new MillisecondClock(1);
>
>
> public static void main(String[] args)
> {
> long nowTime = 0;
>
> //test system currentTimeMillis
> long startTime = System.currentTimeMillis();
> long endTime;
> for(int i = 0;i < 100000000;i++)
> {
> nowTime = System.currentTimeMillis();
> }
> endTime = System.currentTimeMillis();
> System.out.println("Time cost: " + (endTime-startTime));
>
> //test my currentTimeMillis
> CLOCK.start();
> startTime = System.currentTimeMillis();
> for(int i = 0;i < 100000000;i++)
> {
> nowTime = CLOCK.currentTimeMillis();
> }
> endTime = System.currentTimeMillis();
> System.out.println("Time cost: " + (endTime-startTime));
>
> }
> }
> ########
>
> Regards
> Fengbin Fang
>
