使用Java线程作为任务sheduler，

Question

i want to schedule task every amount of milliseconds, and i know about Timers, Executors and so on. I found that this method is the most accurate. But i just want to know can my way be too heavy for a (big) program?

    new Thread(() -> {
        long time = System.currentTimeMillis();
        while (true) {
            if (System.currentTimeMillis() - time >= 1000) {
                // Scheduled task
                System.out.println(new SimpleDateFormat("HH:mm:ss:SSS").format(new Date(System.currentTimeMillis())));
                time = System.currentTimeMillis();
            }
        }
    }).start();

Answer 1

Your method creates a new thread for each repetitive task. Each thread requires allocation of an entire stack. As a result, the memory consumption of your method is a lot bigger than it needs to be. This could become an issue if you create enough of these timer threads.

You would be better off using a java.util.Timer and TimerTasks if you are going to have a large number of these tasks.

Incidentally, as written, your task timing will drift, because occasionally there will be an extra millisecond or more between the triggering of the task and resetting the time variable. That can be fixed in your code, though.

Answer 2

Your code has multiple issue.

1.Your code is continuously executing though it should wait for the given time if it is not ready.You can use delay queue or other concurrent api available where if item is not ready it may wait or sleep and when item ready it will notify the worker thread.

2.It is single threaded if it breaks or one task taking long time then it will escape next schedule.And it is not logically schedule on every 30 sec for an example.It is counting after execution completion from where it is calculating.