大家来帮我看看这个 java 内存问题吧，我快崩溃了。

public HashMap<Integer ,LinkedList<Node> > getDistMatrix(String fileName,HashMap<Integer,ArrayList<Integer>> clusterSet){

HashMap<Integer,LinkedList<Node> > dist_matrix= new HashMap<Integer ,LinkedList<Node>>(2173370);
try{
File myFile = new File(fileName);
FileReader reader = new FileReader(myFile);
BufferedReader breader = new BufferedReader(reader);

System.out.println("start to load the distance matrix to memory . ");
String line = null;
int index = 0;
LinkedList<Node> top50 = null;
int userA = -1;
while((line = breader.readLine())!=null){
if(index%1000000==0){
System.out.println("have loading "+index+" lines .");
}
if(index%50 == 0){
top50 = new LinkedList<Node>();
String [] tokens = line.split(",");
ArrayList<Integer> set = new ArrayList<Integer>();
userA = Integer.parseInt(tokens[0]);
set.add(userA);
clusterSet.put(userA, set);
}

String [] tokens = line.split(",");
int userB = Integer.parseInt(tokens[1]);
int distance = Integer.parseInt(tokens[2]);
Node node = new Node(userB,distance);
//HashMap<Integer, LinkedList<Node>> top50;
top50.addLast(node);
if(index%50 == 49){
//System.out.println("the length of top50 is : "+top50.size());
dist_matrix.put(userA, top50);
}
index++;
}

breader.close();
System.out.println("finish getting the distance matrix . ");
}catch(Exception x ){x.printStackTrace();}

return dist_matrix;
}



class Node implements Comparable<Node>{

Integer imsi;
Integer dist;

public int compareTo(Node s){
return dist.compareTo(s.getDist());
}

public Node(){
imsi = -1;
dist = Integer.MAX_VALUE;
}

public Node(Integer imsiNo,int distance){
imsi = imsiNo;
dist = distance;
}

public int getDist(){
return dist;
}

public Integer getImsi(){
return imsi;
}

public void setImsi(Integer _imsi){
imsi = _imsi;
}
}