Double checked locking in Android

Question

According to many, the somewhat common Double-Checked Locking idiom is broken for java unless you're running 1.5 or later and use the volatile keyword.

A broken double-checked lock sample:

// Broken multithreaded version
// "Double-Checked Locking" idiom
class Foo { 
  private Helper helper = null;
  public Helper getHelper() {
    if (helper == null) 
      synchronized(this) {
        if (helper == null) 
          helper = new Helper();
      }    
    return helper;
    }
  // other functions and members...
  }

The sample comes from this article, which also provides details on how to fix it: http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html

Pugh's analysis above is for Java VMs. I work on Android and frequently use libraries that employ Double-Checked Locking. Does the dalvik VM's memory model support this idiom?

Answer 1

The answer to this question implies that the memory models should be the same, and that the new double checked locking idiom will work.