http://www.theserverside.com Most recent forum messages en Jive Forums Silver 5.5.30 (www.jivesoftware.com) Sun, 19 May 2013 22:58:39 -0400 http://www.theserverside.com/discussions/thread.tss?thread_id=39606 Sat, 13 Dec 2008 14:34:18 -0500 Sat, 13 Dec 2008 14:34:18 -0500 Sat, 13 Dec 2008 14:34:18 -0500 Dec 13, 2008 Samuel Branch 0 http://www.theserverside.com/discussions/thread.tss?thread_id=39606 Wed, 12 Apr 2006 13:24:15 -0400 Wed, 12 Apr 2006 13:24:15 -0400 Wed, 12 Apr 2006 13:24:15 -0400 Apr 12, 2006 Jason Weinstein 1 http://www.theserverside.com/discussions/thread.tss?thread_id=39606
A coworker suggested using copy on write, but the source for CopyOnWriteArrayList uses synchronization in its reads.

As you hinted i did take a look at the ConcurrentHashMap, the source! It turns out i don't...]]> Wed, 12 Apr 2006 02:46:10 -0400 Wed, 12 Apr 2006 02:46:10 -0400 Wed, 12 Apr 2006 02:46:10 -0400 Apr 12, 2006 Jason Weinstein 2 http://www.theserverside.com/discussions/thread.tss?thread_id=39606 I'd like to think that there is a solution, or that in some case the compiler cannot do the optimization.
I'm not really an expert on how the VM may optimize these things or when the cache must be flushed. Personally, I don't...]]> Tue, 11 Apr 2006 09:31:51 -0400 Tue, 11 Apr 2006 09:31:51 -0400 Tue, 11 Apr 2006 09:31:51 -0400 Apr 11, 2006 James Watson 3 http://www.theserverside.com/discussions/thread.tss?thread_id=39606
Now is it not possible to force the correct state somehow?

private Object obj = null;

public Object getObject()...]]> Mon, 10 Apr 2006 21:04:32 -0400 Mon, 10 Apr 2006 21:04:32 -0400 Mon, 10 Apr 2006 21:04:32 -0400 Apr 10, 2006 Jason Weinstein 4 http://www.theserverside.com/discussions/thread.tss?thread_id=39606 I really would like to know that a compiler can optimize this code to make it not work.
I's the same as the dobule-checked locking version. The Object reference could be non-null before it is fully created. When the thread...]]> Mon, 10 Apr 2006 09:46:06 -0400 Mon, 10 Apr 2006 09:46:06 -0400 Mon, 10 Apr 2006 09:46:06 -0400 Apr 10, 2006 James Watson 5 http://www.theserverside.com/discussions/thread.tss?thread_id=39606 Mon, 10 Apr 2006 09:37:34 -0400 Mon, 10 Apr 2006 09:37:34 -0400 Mon, 10 Apr 2006 09:37:34 -0400 Apr 10, 2006 James Watson 0 http://www.theserverside.com/discussions/thread.tss?thread_id=39606
This is the correct way.

private Object obj = null;

public...]]> Fri, 07 Apr 2006 15:03:53 -0400 Fri, 07 Apr 2006 15:03:53 -0400 Fri, 07 Apr 2006 15:03:53 -0400 Apr 7, 2006 Jason Weinstein 7 http://www.theserverside.com/discussions/thread.tss?thread_id=39606
    public final Object getObject() throws Exception...]]> Fri, 07 Apr 2006 07:56:23 -0400 Fri, 07 Apr 2006 07:56:23 -0400 Fri, 07 Apr 2006 07:56:23 -0400 Apr 7, 2006 Sergey Vladimirov 8 http://www.theserverside.com/discussions/thread.tss?thread_id=39606
I will just quote one part from background link.

"It doesn't work
There are lots of reasons it doesn't work. The first couple of reasons we'll describe are more obvious. After understanding those, you may be tempted to try to...]]> Fri, 07 Apr 2006 07:35:59 -0400 Fri, 07 Apr 2006 07:35:59 -0400 Fri, 07 Apr 2006 07:35:59 -0400 Apr 7, 2006 Sergey Vladimirov 0 http://www.theserverside.com/discussions/thread.tss?thread_id=39606
http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html

Introduction.

In a highly concurrent application...]]> Fri, 24 Mar 2006 18:32:18 -0500 Fri, 24 Mar 2006 18:32:18 -0500 Fri, 24 Mar 2006 18:32:18 -0500 Mar 24, 2006 Jason Weinstein 10