我刚刚意识到我在Interlocked.CompareExchange中分配了很多对象并将它们扔给GC，因为与&&或{{1}相比，总是会评估值（第二个参数） }，使用short-circuit evaluation 。
锁定是原子检查null的唯一替代方法，仅当目标位置为||时才分配新对象吗？
此测试打印“我已创建”三次，并在最后一次断言时失败。
null在我的真实代码中，我使用internal class TestCompareExchange {
public static TestCompareExchange defalt = new TestCompareExchange();
public static bool allocated = false;
public TestCompareExchange() {
allocated = true;
Console.WriteLine("I am created");
}
}
[Test]
public void CompareExchangeAllocatesValue() {
if (TestCompareExchange.allocated && (new TestCompareExchange()) != null) // the second part after && is not evaluated
{
}
Assert.IsFalse(TestCompareExchange.allocated);
TestCompareExchange target = null;
var original = Interlocked.CompareExchange(ref target, new TestCompareExchange(), (TestCompareExchange)null);
Assert.AreEqual(null, original);
Assert.IsTrue(TestCompareExchange.allocated);
TestCompareExchange.allocated = false;
target = null;
original = Interlocked.CompareExchange(ref target, new TestCompareExchange(), TestCompareExchange.defalt);
Assert.AreEqual(null, original);
Assert.IsFalse(TestCompareExchange.allocated); // no exchange, but objetc is allocated
}
而不是假对象。有关系吗？是否存在一些TCS对象的池，这使得分配和集合与它们无关？
答案 0 :(得分：3)
在执行Interlocked操作和分配之前，请查看目标位置是否已为空。如果是，则无需尝试初始化它。
if (Volatile.Read(ref target) == null) InitAtomically();