Sharing common array between multiple threads

Question

I am trying to implement a 2phase Resource Lock Deadlock Prevention algorithm in Java. After multiple attempts, I have settled on creating a SimpleProcess class that implements the Runnable interface that will act as my thread. The structure of SimpleProcess looks somewhat like this:

public class SimpleProcess implements Runnable
{
    private int pid; // process id
    private ArrayList<Integer> requiredRes; // originally required resources
    private int[] remainingRes; // resources that are still required
    private boolean status; // whether process is completed running or not

    public SimpleProcess() {
        pid = 0;
        status = false;
    }

    public SimpleProcess(int id, ArrayList<Integer> res) {
        pid = id;
        requiredRes = res;
        remainingres = requiredRes;
        status = false;
    }

    public int getPid() {
        return pid;
    }

    public int[] getRequiredRes() {
        return requiredRes;
    }

    public int[] getRemainingRequiredRes() {
        return remainingRes;
    }

    public boolean getStatus() {
        return status;
    }

    public void run() {
        System.out.println("Process " + pid + " started.");
        // do something
        System.out.println("Process " + pid + " is complete.");
    }

}

My main class will contain a variable that contains lock status for each resource. This variable is implemented as final Lock[] locked_res = ReentrantLock[nr] . What I need help is with finding a way to share this same variable whose value can be changed by each thread to be shared among all the threads (SimpleProcess instances).

Answer 1

You can use the volatile keyword for multi-thread sharing