CODEWITHSUNDEEP
javamultithreadingsemaphoresynchronized
SHE
SHE

Reputation: 121

Synchronized multi-threading vs single thread

I am trying to count 100 numbers by multi-threading and single-threading. Since synchronized keyword allows only one thread at a time (it is kind of like a single thread), so these two methods below should have the same runtime approximately if we ignore the effect of time consuming of creating and synchronizing threads?

Multi-threading using synchronized:

public synchronized static void increment() {
    sum++;
}

public static void main(String[] args) {
    Thread t1 = new Thread(new Runnable() {
        @Override
        public void run() {
            for (int i = 0; i < 50; i++) {
                increment();
            }
        }
    });
    Thread t2 = new Thread(new Runnable() {
        @Override
        public void run() {
            for (int i = 0; i < 50; i++) {
                increment();
            }
        }
    });
    t1.start();;
    t2.start();
    try {
        t1.join();
        t2.join();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    System.out.println(sum);

Single-threading:

public static void main(String[] args) {
    for (int i = 0; i < 100; i++) {
        sum++
    }

    System.out.println(sum);
}

Upvotes: 1

Views: 828

Answers (1)

Scott Twombly
Scott Twombly

Reputation: 84

Java is really good at multithreading, but there is a lot of overhead with creating and synchronizing threads, so don't be surprised if, for a simple problem like counting to 100, you actually see an increase in runtime.

Upvotes: 1

Related Questions