Java 垃圾收集如何与循环引用一起使用?

2022-01-16 00:00:00 garbage-collection java

据我了解,Java 中的垃圾回收会清理一些对象,如果没有其他对象指向"该对象.

From my understanding, garbage collection in Java cleans up some objects if nothing else is 'pointing' to that object.

我的问题是,如果我们有这样的事情会发生什么:

My question is, what happens if we have something like this:

class Node {
    public object value;
    public Node next;
    public Node(object o, Node n) { value = 0; next = n;}
}

//...some code
{
    Node a = new Node("a", null), 
         b = new Node("b", a), 
         c = new Node("c", b);
    a.next = c;
} //end of scope
//...other code

abc 应该被垃圾回收,但它们都被其他对象引用.

a, b, and c should be garbage collected, but they are all being referenced by other objects.

Java 垃圾收集如何处理这个问题?(或者仅仅是内存消耗?)

How does the Java garbage collection deal with this? (or is it simply a memory drain?)

推荐答案

如果无法通过从垃圾收集根开始的链访问对象,Java 的 GC 会将其视为垃圾",因此将收集这些对象.即使对象可能相互指向形成一个循环,但如果从根部切断它们仍然是垃圾.

Java's GC considers objects "garbage" if they aren't reachable through a chain starting at a garbage collection root, so these objects will be collected. Even though objects may point to each other to form a cycle, they're still garbage if they're cut off from the root.

请参阅 Java 平台中的附录 A:垃圾收集的真相中关于不可访问对象的部分性能:战略和战术 用于血淋淋的细节.

See the section on unreachable objects in Appendix A: The Truth About Garbage Collection in Java Platform Performance: Strategies and Tactics for the gory details.

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