Vfrdtyky

This is my code:

public static void runSGD(double R, double theta, double convergenceTol)

{

    List<Integer> allEdges = new ArrayList<Integer>(2*E);    

    for (int i = 0; i < 2*E; i++) 

        allEdges.add(i);

    Collections.shuffle(allEdges, new Random(shuffleSeed));

    double oldRes = calcObj(R, theta, allEdges), newRes = 0.0;

    long numEdges = 0;

    for (int _e = 0; _e < 2*E*tp; _e++) {

        int e = allEdges.get(_e);

        numEdges += weights.get(e);

    }

    if (verbose)

        System.out.printf("[Info] Number of edges in training, including multiplicity = %dn", numEdges);

    int edgeTable = new int[4][1<<30];

    long part = 0; int cur = 0;

    for (long i = 0; i < numEdges; i++) {

        if (i+1 > part) {

            part += weights.get(allEdges.get(cur));

            cur++;

        }

        int row = (int) (i >>> 30);

        int col = (int) (i & ((1 << 30) -1));

        edgeTable[row][col] = allEdges.get(cur-1);

    }

}

The error is Exception in thread "main" java.lang.OutOfMemoryError: Java heap space when run this code:

 int edgeTable = new int[4][1<<30];

I have try -Xmx1g,-Xmx3g, but didn't work ,how to fix it?

You are allocating 4 int arrays of 2^30 ints. That is 2^34 bytes or 16 gigabytes. Clearly that won't fit into a 1 or 3 gigabyte heap. Indeed, a typical laptop or PC won't have enough RAM for this ...

In fact the JVM supports arrays of just under 2^31 elements; see Do Java arrays have a maximum size?, so the array size per se is not the problem here.

As others mentioned, you are trying to allocate huge arrays. You can try by allocating chunks of small array or try collections.

Arrays use ints to address single array elements. The maximum int-value is 2^31-1.
You create 4 Arrays of the size 2^30 which means you have 2^32 elements in your array.
Java does simple not support arrays of that size.

You can fix it by making 4 distinct arrays.

Also allocating 3GB with -Xmx3g wont help, since your array alone will need 16GB of RAM.