對象參數在Monitor.Enter調用中的作用.Net

Question

我們都知道下面的代碼是用來形成臨界區的。

public class CommonResource 
{ 
    public object obj = new object(); 

    public void PopularFunction() 
    { 
     lock (obj) 
     { 
      ///Access variable that we want to protect form being accessed concurrently 
      ///This forms critical section 
      ///My question is what is role'obj' plays in forming critical section. 
      ///How it works behind the scene. 
     } 

     ///Above code can be written as 

     Monitor.Enter(obj); 
     ///Access variable that we want to protect form being accessed concurrently 
     ///This forms critical section 
     ///My question is what is role'obj' plays in forming critical section. 
     ///How it works behind the scene. 
     Monitor.Exit(obj); 
    } 
} 

我的問題是Monitor.Enter如何在'obj'的幫助下形成一個關鍵部分。如果我們需要總是傳遞一個對象，爲什麼不能明確地傳遞任何對象。肯定有這個背後的原因。有人可以解釋嗎？

感謝， 與Hemant

Answer 1

你傳遞一個對象作爲鎖的標識符使用。你看我有以下類：

public class LockTest 
{ 
    private object obj1 = new object(); 
    private object obj2 = new object(); 

    public void Method1() 
    { 
     lock(obj1) 
     { 
      ... 
     } 
    } 

    public void Method2() 
    { 
     lock(obj2) 
     { 
      ... 
     } 
    } 

    public void Method3() 
    { 
     lock(obj1) 
     { 
      ... 
     } 
    } 
} 

如果我打電話給Method1和Method2從不同的線程，既不調用將阻止其他的，因爲他們是在不同的對象鎖定。但是，如果我要從不同的線程調用Method1和Method3，則執行lock(obj1)的第一個線程將阻塞另一個線程的執行，直到在塊的末尾釋放鎖定爲止。

Answer 2

它用於框架知道鎖的scope。

基本上，您要麼使用靜態對象，要麼使用非靜態對象。

public class Foo 
{ 
    private object sync = new object(); 
    public void Bar() 
    { 
     lock (this.sync) 
     { 
      // You can call new Foo().Bar() multiple times, because 
      // each Foo class lock its own instance of the sync object 
     } 
    } 
} 

public class Foo 
{ 
    private static object sync = new object(); 
    public void Bar() 
    { 
     lock (sync) 
     { 
      // You can't call new Foo().Bar() multiple times, because 
      // each Foo class lock the same instance of the sync object 
     } 
    } 
}