在ConcurrentHashMap中存储复杂对象

Question

As per Java Concurrency in Practice below code can throw assertion Error:

If a thread other than the publishing thread were to call assertSanity, it could throw AssertionError

  public class Holder {
private int n;
public Holder(int n) { this.n = n; }
public void assertSanity() {
if (n != n)
throw new AssertionError("This statement is false.");
}
}

// Unsafe publication
public Holder holder;
public void initialize() {
holder = new Holder(42);
}

Question is: If I save, an object which refers to other objects in a ConcurrentHashMap, is there a possibility that certain updates on this object graph will not be in sync, in a multi-threaded environment due to same reasons as mentioned for above example?

Though root node in object graph will always be updated in map for all threads, but what about other objects which are referred as fields in root node, if these are not final or volatile ?

Answer 1

Answering my own question, I should have read complete chapter before asking question. This is what later part of chapter says:

Mutable objects: If an object may be modified after construction, safe publication ensures only the visibility of the as-published state. Synchronization must be used not only to publish a mutable object, but also every time the object is accessed to ensure visibility of subsequent modifications. To share mutable objects safely, they must be safely published and be either thread-safe or guarded by a lock.

So using CHM or any thread safe collection is unsafe in a multithreaded environment, unless you synchronize changes to your mutable objects in CHM or these objects are immutable.

Answer 2

ConcurrentHashMap保证所有带有引用（链接到对象）的操作（保存在ConcurrentHashMap中）都是线程安全的，但是，当然，ConcurrentHashMap不能保证每个对象的线程安全，并且存储引用（链接）在ConcurrentHashMap中。