CODEWITHSUNDEEP
javamultithreading
isklenar
isklenar

Reputation: 994

Synchronized object in multiple threads

I have a class that creates multiple threads, each thread gets an socket as parameter in constructor.

I need to synchronize the threads, so that only one thread accesses the sockets streams at given time.

Here is quick draft of what I need:

class MyClass{
    Socket socket;

    public MyClass() {
        socket = new Socket(address, port);
    }

    void createThread(){
        Worker worker = new Worker(socket);
        Thread t = new Thread(worker);
        t.start();
    }

    void doStuff(){
        InputStream is = socket.getInputStream();
        /* ... */
    }
}

class Worker implements Runnable{
    Socket socket;

    public Worker(Socket socket){
        this.socket = socket;
    }


    @Override
    public void run() {
        InputStream is = socket.getInputStream();
        /* ... */
    }

}

Now here, potentially multiple threads can access sockets input stream at the same time, which would be very bad.

Now my question is: will synchronized keyword work for this case?

Upvotes: 2

Views: 454

Answers (1)

David Harkness
David Harkness

Reputation: 36562

To use basic synchronization you could use the socket as the lock since it's shared by each worker.

public void run() {
    synchronized (socket) {
        InputStream is = socket.getInputStream();
        /* ... */
    }
}

If MyClass really needs to access the socket as well, perform the same synchronization in doStuff.

However, you're effectively serializing access to the socket and bypassing the multi-threaded aspect of your application since the lock is held during the entire duration of the run method.

Upvotes: 6

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