【发布时间】：2010-11-21 21:32:46
【问题描述】：
我正在阅读http://www.mono-project.com/ThreadsBeginnersGuide。
第一个示例如下所示：
public class FirstUnsyncThreads {
private int i = 0;
public static void Main (string[] args) {
FirstUnsyncThreads myThreads = new FirstUnsyncThreads ();
}
public FirstUnsyncThreads () {
// Creating our two threads. The ThreadStart delegate is points to
// the method being run in a new thread.
Thread firstRunner = new Thread (new ThreadStart (this.firstRun));
Thread secondRunner = new Thread (new ThreadStart (this.secondRun));
// Starting our two threads. Thread.Sleep(10) gives the first Thread
// 10 miliseconds more time.
firstRunner.Start ();
Thread.Sleep (10);
secondRunner.Start ();
}
// This method is being excecuted on the first thread.
public void firstRun () {
while(this.i < 10) {
Console.WriteLine ("First runner incrementing i from " + this.i +
" to " + ++this.i);
// This avoids that the first runner does all the work before
// the second one has even started. (Happens on high performance
// machines sometimes.)
Thread.Sleep (100);
}
}
// This method is being excecuted on the second thread.
public void secondRun () {
while(this.i < 10) {
Console.WriteLine ("Second runner incrementing i from " + this.i +
" to " + ++this.i);
Thread.Sleep (100);
}
}
}
输出：
First runner incrementing i from 0 to 1
Second runner incrementing i from 1 to 2
Second runner incrementing i from 3 to 4
First runner incrementing i from 2 to 3
Second runner incrementing i from 5 to 6
First runner incrementing i from 4 to 5
First runner incrementing i from 6 to 7
Second runner incrementing i from 7 to 8
Second runner incrementing i from 9 to 10
First runner incrementing i from 8 to 9
哇，这是什么？不幸的是，文章中的解释对我来说是不充分的。你能解释一下为什么增量顺序混乱吗？
谢谢！
【问题讨论】：
-
参考文章的作者说输出“可能”如图所示。从某种意义上说，这是正确的，因为您无法证明输出不会如图所示。然而，在实践中，考虑到 First 大约有 10 毫秒的领先优势，您会期望在发生任何“混乱”之前看到锁步交替进行相当多的迭代。
标签： c# multithreading