作为我代码的一部分，我需要为具有 70k 顶点和 700k 边的图计算一些中心性度量。为此，我使用了数组和哈希映射数据结构。不幸的是，我在程序中间耗尽了内存。处理这种情况的最佳 JVM 热点参数是什么？这是我得到的例外：
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.HashMap.createEntry(Unknown Source)
at java.util.HashMap.addEntry(Unknown Source)
at java.util.HashMap.put(Unknown Source)
所以我用 -Xmx6g 改变了堆大小，但是这个参数没有解决问题。我仍然对堆空间有同样的问题。
在我的程序中，我想为每个节点计算一些度量值，不幸的是 JVM 保留所有节点的信息并尝试为每个节点计算它。我想知道有什么方法可以改变 JVM 以从内存中删除不需要的信息？例如，我的代码在从 70000 个节点计算 1000 个节点的度量后崩溃。无论如何在计算后从内存中删除与这 1000 个节点相关的信息？内存可以通过这种方式分配给其他节点。这与垃圾收集器有关吗？ 这是我的代码（使用 JUNG 库）
public class FindMostCentralNodes {
private DirectedSparseGraph<Customer, Transaction> network = new DirectedSparseGraph<Customer, Transaction>();
static String dbName="SNfinal";
private int numberofNodes=0;
public static void main(String[] args) throws NumberFormatException, SQLException {
FindMostCentralNodes f=new FindMostCentralNodes();
int counter=1;
DirectedSparseGraph<Customer, Transaction> tsn=f.getTSN();
DistanceCentralityScorer<Customer,Transaction> scorer=new DistanceCentralityScorer<Customer,Transaction>(tsn,false,true,true);// un-weighted
Collection<Customer> subscribers=tsn.getVertices();
for(Customer node:subscribers){
String sql="update Node set dist_centrality='"+scorer.getVertexScore(node)+"' where subscriber='"+node.getName()+"'";
DatabaseManager.executeUpdate(sql,dbName);
System.out.println("Update node centrality measures successfully!: "+counter++);
node=null;
}
}
public DirectedSparseGraph<Customer,Transaction> getTSN() throws NumberFormatException, SQLException{
network= new DirectedSparseGraph<Customer,Transaction>();
String count="select count(*) as counter from Node";
ResultSet rscount=DatabaseManager.executeQuery(count, dbName);
if(rscount.next()) {
numberofNodes=rscount.getInt("counter");
}
Customer [] subscribers=new Customer[numberofNodes];
String sql="select * from Node";
ResultSet rs=DatabaseManager.executeQuery(sql, dbName);
while(rs.next()){
Customer sub=new Customer();
sub.setName(rs.getString("subscriber"));
network.addVertex(sub);
subscribers[rs.getInt("nodeID")-1]=sub;
sub=null;
}
String sql2="select * from TSN";
ResultSet rs2=DatabaseManager.executeQuery(sql2, dbName);
while(rs2.next()){
Transaction transaction=new Transaction(Double.parseDouble(rs2.getString("weight")));
network.addEdge( transaction, subscribers[rs2.getInt("callerNID")-1], subscribers[rs2.getInt("calleeNID")-1] );
transaction=null;
}
//garbage
rscount=null;
rs=null;
rs2=null;
subscribers=null;
return network;
}
}