ReaderWriterLock 类

定义

命名空间:

System.Threading

程序集:

System.Threading.dll

Source:

ReaderWriterLock.cs

定义支持单个写线程和多个读线程的锁。

public ref class ReaderWriterLock sealed : System::Runtime::ConstrainedExecution::CriticalFinalizerObject

public sealed class ReaderWriterLock : System.Runtime.ConstrainedExecution.CriticalFinalizerObject

type ReaderWriterLock = class
    inherit CriticalFinalizerObject

Public NotInheritable Class ReaderWriterLock
Inherits CriticalFinalizerObject

继承

Object

CriticalFinalizerObject

ReaderWriterLock

示例

以下示例演示如何使用 ReaderWriterLock 来保护共享资源（名为 resource的整数值），该整数值由多个线程并发读取和独占写入。 请注意， ReaderWriterLock 是在类级别声明的，以便对所有线程可见。

// This example shows a ReaderWriterLock protecting a shared
// resource that is read concurrently and written exclusively
// by multiple threads.
// The complete code is located in the ReaderWriterLock
// class topic.
using namespace System;
using namespace System::Threading;
public ref class Test
{
public:

   // Declaring the ReaderWriterLock at the class level
   // makes it visible to all threads.
   static ReaderWriterLock^ rwl = gcnew ReaderWriterLock;

   // For this example, the shared resource protected by the
   // ReaderWriterLock is just an integer.
   static int resource = 0;

   literal int numThreads = 26;
   static bool running = true;

   // Statistics.
   static int readerTimeouts = 0;
   static int writerTimeouts = 0;
   static int reads = 0;
   static int writes = 0;
   static void ThreadProc()
   {
      Random^ rnd = gcnew Random;

      // As long as a thread runs, it randomly selects
      // various ways to read and write from the shared
      // resource. Each of the methods demonstrates one
      // or more features of ReaderWriterLock.
      while ( running )
      {
         double action = rnd->NextDouble();
         if ( action < .8 )
                  ReadFromResource( 10 );
         else
         if ( action < .81 )
                  ReleaseRestore( rnd, 50 );
         else
         if ( action < .90 )
                  UpgradeDowngrade( rnd, 100 );
         else
                  WriteToResource( rnd, 100 );
      }
   }


   // Shows how to request and release a reader lock, and
   // how to handle time-outs.
   static void ReadFromResource( int timeOut )
   {
      try
      {
         rwl->AcquireReaderLock( timeOut );
         try
         {

            // It is safe for this thread to read from
            // the shared resource.
            Display( String::Format( "reads resource value {0}", resource ) );
            Interlocked::Increment( reads );
         }
         finally
         {

            // Ensure that the lock is released.
            rwl->ReleaseReaderLock();
         }

      }
      catch ( ApplicationException^ )
      {

         // The reader lock request timed out.
         Interlocked::Increment( readerTimeouts );
      }

   }


   // Shows how to request and release the writer lock, and
   // how to handle time-outs.
   static void WriteToResource( Random^ rnd, int timeOut )
   {
      try
      {
         rwl->AcquireWriterLock( timeOut );
         try
         {

            // It is safe for this thread to read or write
            // from the shared resource.
            resource = rnd->Next( 500 );
            Display( String::Format( "writes resource value {0}", resource ) );
            Interlocked::Increment( writes );
         }
         finally
         {

            // Ensure that the lock is released.
            rwl->ReleaseWriterLock();
         }

      }
      catch ( ApplicationException^ )
      {

         // The writer lock request timed out.
         Interlocked::Increment( writerTimeouts );
      }

   }


   // Shows how to request a reader lock, upgrade the
   // reader lock to the writer lock, and downgrade to a
   // reader lock again.
   static void UpgradeDowngrade( Random^ rnd, int timeOut )
   {
      try
      {
         rwl->AcquireReaderLock( timeOut );
         try
         {

            // It is safe for this thread to read from
            // the shared resource.
            Display( String::Format( "reads resource value {0}", resource ) );
            Interlocked::Increment( reads );

            // If it is necessary to write to the resource,
            // you must either release the reader lock and
            // then request the writer lock, or upgrade the
            // reader lock. Note that upgrading the reader lock
            // puts the thread in the write queue, behind any
            // other threads that might be waiting for the
            // writer lock.
            try
            {
               LockCookie lc = rwl->UpgradeToWriterLock( timeOut );
               try
               {

                  // It is safe for this thread to read or write
                  // from the shared resource.
                  resource = rnd->Next( 500 );
                  Display( String::Format( "writes resource value {0}", resource ) );
                  Interlocked::Increment( writes );
               }
               finally
               {

                  // Ensure that the lock is released.
                  rwl->DowngradeFromWriterLock( lc );
               }

            }
            catch ( ApplicationException^ )
            {

               // The upgrade request timed out.
               Interlocked::Increment( writerTimeouts );
            }


            // When the lock has been downgraded, it is
            // still safe to read from the resource.
            Display( String::Format( "reads resource value {0}", resource ) );
            Interlocked::Increment( reads );
         }
         finally
         {

            // Ensure that the lock is released.
            rwl->ReleaseReaderLock();
         }

      }
      catch ( ApplicationException^ )
      {

         // The reader lock request timed out.
         Interlocked::Increment( readerTimeouts );
      }

   }


   // Shows how to release all locks and later restore
   // the lock state. Shows how to use sequence numbers
   // to determine whether another thread has obtained
   // a writer lock since this thread last accessed the
   // resource.
   static void ReleaseRestore( Random^ rnd, int timeOut )
   {
      int lastWriter;
      try
      {
         rwl->AcquireReaderLock( timeOut );
         try
         {

            // It is safe for this thread to read from
            // the shared resource. Cache the value. (You
            // might do this if reading the resource is
            // an expensive operation.)
            int resourceValue = resource;
            Display( String::Format( "reads resource value {0}", resourceValue ) );
            Interlocked::Increment( reads );

            // Save the current writer sequence number.
            lastWriter = rwl->WriterSeqNum;

            // Release the lock, and save a cookie so the
            // lock can be restored later.
            LockCookie lc = rwl->ReleaseLock();

            // Wait for a random interval (up to a
            // quarter of a second), and then restore
            // the previous state of the lock. Note that
            // there is no timeout on the Restore method.
            Thread::Sleep( rnd->Next( 250 ) );
            rwl->RestoreLock( lc );

            // Check whether other threads obtained the
            // writer lock in the interval. If not, then
            // the cached value of the resource is still
            // valid.
            if ( rwl->AnyWritersSince( lastWriter ) )
            {
               resourceValue = resource;
               Interlocked::Increment( reads );
               Display( String::Format( "resource has changed {0}", resourceValue ) );
            }
            else
            {
               Display( String::Format( "resource has not changed {0}", resourceValue ) );
            }
         }
         finally
         {

            // Ensure that the lock is released.
            rwl->ReleaseReaderLock();
         }

      }
      catch ( ApplicationException^ )
      {

         // The reader lock request timed out.
         Interlocked::Increment( readerTimeouts );
      }

   }


   // Helper method briefly displays the most recent
   // thread action. Comment out calls to Display to
   // get a better idea of throughput.
   static void Display( String^ msg )
   {
      Console::Write( "Thread {0} {1}.       \r", Thread::CurrentThread->Name, msg );
   }

};


int main()
{
   array<String^>^args = Environment::GetCommandLineArgs();

   // Start a series of threads. Each thread randomly
   // performs reads and writes on the shared resource.
   array<Thread^>^t = gcnew array<Thread^>(Test::numThreads);
   for ( int i = 0; i < Test::numThreads; i++ )
   {
      t[ i ] = gcnew Thread( gcnew ThreadStart( Test::ThreadProc ) );
      t[ i ]->Name = gcnew String( Convert::ToChar( i + 65 ),1 );
      t[ i ]->Start();
      if ( i > 10 )
            Thread::Sleep( 300 );

   }

   // Tell the threads to shut down, then wait until they all
   // finish.
   Test::running = false;
   for ( int i = 0; i < Test::numThreads; i++ )
   {
      t[ i ]->Join();

   }

   // Display statistics.
   Console::WriteLine( "\r\n {0} reads, {1} writes, {2} reader time-outs, {3} writer time-outs.", Test::reads, Test::writes, Test::readerTimeouts, Test::writerTimeouts );
   Console::WriteLine( "Press ENTER to exit." );
   Console::ReadLine();
   return 0;
}

// The complete code is located in the ReaderWriterLock class topic.
using System;
using System.Threading;

public class Example
{
   static ReaderWriterLock rwl = new ReaderWriterLock();
   // Define the shared resource protected by the ReaderWriterLock.
   static int resource = 0;

   const int numThreads = 26;
   static bool running = true;

   // Statistics.
   static int readerTimeouts = 0;
   static int writerTimeouts = 0;
   static int reads = 0;
   static int writes = 0;

   public static void Main()
   {
      // Start a series of threads to randomly read from and
      // write to the shared resource.
      Thread[] t = new Thread[numThreads];
      for (int i = 0; i < numThreads; i++){
         t[i] = new Thread(new ThreadStart(ThreadProc));
         t[i].Name = new String((char)(i + 65), 1);
         t[i].Start();
         if (i > 10)
            Thread.Sleep(300);
      }

      // Tell the threads to shut down and wait until they all finish.
      running = false;
      for (int i = 0; i < numThreads; i++)
         t[i].Join();

      // Display statistics.
      Console.WriteLine("\n{0} reads, {1} writes, {2} reader time-outs, {3} writer time-outs.",
            reads, writes, readerTimeouts, writerTimeouts);
      Console.Write("Press ENTER to exit... ");
      Console.ReadLine();
   }

   static void ThreadProc()
   {
      Random rnd = new Random();

      // Randomly select a way for the thread to read and write from the shared
      // resource.
      while (running) {
         double action = rnd.NextDouble();
         if (action < .8)
            ReadFromResource(10);
         else if (action < .81)
            ReleaseRestore(rnd, 50);
         else if (action < .90)
            UpgradeDowngrade(rnd, 100);
         else
            WriteToResource(rnd, 100);
      }
   }

   // Request and release a reader lock, and handle time-outs.
   static void ReadFromResource(int timeOut)
   {
      try {
         rwl.AcquireReaderLock(timeOut);
         try {
            // It is safe for this thread to read from the shared resource.
            Display("reads resource value " + resource);
            Interlocked.Increment(ref reads);
         }
         finally {
            // Ensure that the lock is released.
            rwl.ReleaseReaderLock();
         }
      }
      catch (ApplicationException) {
         // The reader lock request timed out.
         Interlocked.Increment(ref readerTimeouts);
      }
   }

   // Request and release the writer lock, and handle time-outs.
   static void WriteToResource(Random rnd, int timeOut)
   {
      try {
         rwl.AcquireWriterLock(timeOut);
         try {
            // It's safe for this thread to access from the shared resource.
            resource = rnd.Next(500);
            Display("writes resource value " + resource);
            Interlocked.Increment(ref writes);
         }
         finally {
            // Ensure that the lock is released.
            rwl.ReleaseWriterLock();
         }
      }
      catch (ApplicationException) {
         // The writer lock request timed out.
         Interlocked.Increment(ref writerTimeouts);
      }
   }

   // Requests a reader lock, upgrades the reader lock to the writer
   // lock, and downgrades it to a reader lock again.
   static void UpgradeDowngrade(Random rnd, int timeOut)
   {
      try {
         rwl.AcquireReaderLock(timeOut);
         try {
            // It's safe for this thread to read from the shared resource.
            Display("reads resource value " + resource);
            Interlocked.Increment(ref reads);

            // To write to the resource, either release the reader lock and
            // request the writer lock, or upgrade the reader lock. Upgrading
            // the reader lock puts the thread in the write queue, behind any
            // other threads that might be waiting for the writer lock.
            try {
               LockCookie lc = rwl.UpgradeToWriterLock(timeOut);
               try {
                  // It's safe for this thread to read or write from the shared resource.
                  resource = rnd.Next(500);
                  Display("writes resource value " + resource);
                  Interlocked.Increment(ref writes);
               }
               finally {
                  // Ensure that the lock is released.
                  rwl.DowngradeFromWriterLock(ref lc);
               }
            }
            catch (ApplicationException) {
               // The upgrade request timed out.
               Interlocked.Increment(ref writerTimeouts);
            }

            // If the lock was downgraded, it's still safe to read from the resource.
            Display("reads resource value " + resource);
            Interlocked.Increment(ref reads);
         }
         finally {
            // Ensure that the lock is released.
            rwl.ReleaseReaderLock();
         }
      }
      catch (ApplicationException) {
         // The reader lock request timed out.
         Interlocked.Increment(ref readerTimeouts);
      }
   }

   // Release all locks and later restores the lock state.
   // Uses sequence numbers to determine whether another thread has
   // obtained a writer lock since this thread last accessed the resource.
   static void ReleaseRestore(Random rnd, int timeOut)
   {
      int lastWriter;

      try {
         rwl.AcquireReaderLock(timeOut);
         try {
            // It's safe for this thread to read from the shared resource,
            // so read and cache the resource value.
            int resourceValue = resource;     // Cache the resource value.
            Display("reads resource value " + resourceValue);
            Interlocked.Increment(ref reads);

            // Save the current writer sequence number.
            lastWriter = rwl.WriterSeqNum;

            // Release the lock and save a cookie so the lock can be restored later.
            LockCookie lc = rwl.ReleaseLock();

            // Wait for a random interval and then restore the previous state of the lock.
            Thread.Sleep(rnd.Next(250));
            rwl.RestoreLock(ref lc);

            // Check whether other threads obtained the writer lock in the interval.
            // If not, then the cached value of the resource is still valid.
            if (rwl.AnyWritersSince(lastWriter)) {
               resourceValue = resource;
               Interlocked.Increment(ref reads);
               Display("resource has changed " + resourceValue);
            }
            else {
               Display("resource has not changed " + resourceValue);
            }
         }
         finally {
            // Ensure that the lock is released.
            rwl.ReleaseReaderLock();
         }
      }
      catch (ApplicationException) {
         // The reader lock request timed out.
         Interlocked.Increment(ref readerTimeouts);
      }
   }

   // Helper method briefly displays the most recent thread action.
   static void Display(string msg)
   {
      Console.Write("Thread {0} {1}.       \r", Thread.CurrentThread.Name, msg);
   }
}

' The complete code is located in the ReaderWriterLock class topic.
Imports System.Threading

Public Module Example
   Private rwl As New ReaderWriterLock()
   ' Define the shared resource protected by the ReaderWriterLock.
   Private resource As Integer = 0

   Const numThreads As Integer = 26
   Private running As Boolean = True
   
   ' Statistics.
   Private readerTimeouts As Integer = 0
   Private writerTimeouts As Integer = 0
   Private reads As Integer = 0
   Private writes As Integer = 0
  
   Public Sub Main()
      ' Start a series of threads to randomly read from and
      ' write to the shared resource.
      Dim t(numThreads - 1) As Thread
      Dim i As Integer
      For i = 0 To numThreads - 1
         t(i) = New Thread(New ThreadStart(AddressOf ThreadProc))
         t(i).Name = Chr(i + 65)
         t(i).Start()
         If i > 10 Then
            Thread.Sleep(300)
         End If
      Next

      ' Tell the threads to shut down and wait until they all finish.
      running = False
      For i = 0 To numThreads - 1
         t(i).Join()
      Next
      
      ' Display statistics.
      Console.WriteLine(vbCrLf & "{0} reads, {1} writes, {2} reader time-outs, {3} writer time-outs.",
                        reads, writes, readerTimeouts, writerTimeouts)
      Console.Write("Press ENTER to exit... ")
      Console.ReadLine()
   End Sub

   Sub ThreadProc()
      Dim rnd As New Random

      ' Randomly select a way for the thread to read and write from the shared
      ' resource.
      While running
         Dim action As Double = rnd.NextDouble()
         If action < 0.8 Then
            ReadFromResource(10)
         ElseIf action < 0.81 Then
            ReleaseRestore(rnd, 50)
         ElseIf action < 0.9 Then
            UpgradeDowngrade(rnd, 100)
         Else
            WriteToResource(rnd, 100)
         End If
      End While
   End Sub
    
   ' Request and release a reader lock, and handle time-outs.
   Sub ReadFromResource(timeOut As Integer)
      Try
         rwl.AcquireReaderLock(timeOut)
         Try
            ' It's safe for this thread to read from the shared resource.
            Display("reads resource value " & resource)
            Interlocked.Increment(reads)
         Finally
            ' Ensure that the lock is released.
            rwl.ReleaseReaderLock()
         End Try
      Catch ex As ApplicationException
         ' The reader lock request timed out.
         Interlocked.Increment(readerTimeouts)
      End Try
   End Sub

   ' Request and release the writer lock, and handle time-outs.
   Sub WriteToResource(rnd As Random, timeOut As Integer)
      Try
         rwl.AcquireWriterLock(timeOut)
         Try
            ' It's safe for this thread to read or write from the shared resource.
            resource = rnd.Next(500)
            Display("writes resource value " & resource)
            Interlocked.Increment(writes)
         Finally
            ' Ensure that the lock is released.
            rwl.ReleaseWriterLock()
         End Try
      Catch ex As ApplicationException
         ' The writer lock request timed out.
         Interlocked.Increment(writerTimeouts)
      End Try
   End Sub

   ' Requests a reader lock, upgrades the reader lock to the writer
   ' lock, and downgrades it to a reader lock again.
   Sub UpgradeDowngrade(rnd As Random, timeOut As Integer)
      Try
         rwl.AcquireReaderLock(timeOut)
         Try
            ' It's safe for this thread to read from the shared resource.
            Display("reads resource value " & resource)
            Interlocked.Increment(reads)
            
            ' To write to the resource, either release the reader lock and
            ' request the writer lock, or upgrade the reader lock. Upgrading
            ' the reader lock puts the thread in the write queue, behind any
            ' other threads that might be waiting for the writer lock.
            Try
               Dim lc As LockCookie = rwl.UpgradeToWriterLock(timeOut)
               Try
                  ' It's safe for this thread to read or write from the shared resource.
                  resource = rnd.Next(500)
                  Display("writes resource value " & resource)
                  Interlocked.Increment(writes)
               Finally
                  ' Ensure that the lock is released.
                  rwl.DowngradeFromWriterLock(lc)
               End Try
            Catch ex As ApplicationException
               ' The upgrade request timed out.
               Interlocked.Increment(writerTimeouts)
            End Try
            
            ' If the lock was downgraded, it's still safe to read from the resource.
            Display("reads resource value " & resource)
            Interlocked.Increment(reads)
         Finally
            ' Ensure that the lock is released.
            rwl.ReleaseReaderLock()
         End Try
      Catch ex As ApplicationException
         ' The reader lock request timed out.
         Interlocked.Increment(readerTimeouts)
      End Try
   End Sub

   ' Release all locks and later restores the lock state.
   ' Uses sequence numbers to determine whether another thread has
   ' obtained a writer lock since this thread last accessed the resource.
   Sub ReleaseRestore(rnd As Random ,timeOut As Integer)
      Dim lastWriter As Integer
      
      Try
         rwl.AcquireReaderLock(timeOut)
         Try
            ' It's safe for this thread to read from the shared resource,
            ' so read and cache the resource value.
            Dim resourceValue As Integer = resource
            Display("reads resource value " & resourceValue)
            Interlocked.Increment(reads)
            
            ' Save the current writer sequence number.
            lastWriter = rwl.WriterSeqNum
            
            ' Release the lock and save a cookie so the lock can be restored later.
            Dim lc As LockCookie = rwl.ReleaseLock()
            
            ' Wait for a random interval and then restore the previous state of the lock.
            Thread.Sleep(rnd.Next(250))
            rwl.RestoreLock(lc)
           
            ' Check whether other threads obtained the writer lock in the interval.
            ' If not, then the cached value of the resource is still valid.
            If rwl.AnyWritersSince(lastWriter) Then
               resourceValue = resource
               Interlocked.Increment(reads)
               Display("resource has changed " & resourceValue)
            Else
               Display("resource has not changed " & resourceValue)
            End If
         Finally
            ' Ensure that the lock is released.
            rwl.ReleaseReaderLock()
         End Try
      Catch ex As ApplicationException
         ' The reader lock request timed out.
         Interlocked.Increment(readerTimeouts)
      End Try
   End Sub

   ' Helper method briefly displays the most recent thread action.
   Sub Display(msg As String)
      Console.Write("Thread {0} {1}.       " & vbCr, Thread.CurrentThread.Name, msg)
   End Sub
End Module

注解

重要

.NET Framework有两个读取器-写入器锁和 ReaderWriterLockSlimReaderWriterLock。 建议对所有新开发的项目使用 ReaderWriterLockSlim。 虽然 ReaderWriterLockSlim 类似于 ReaderWriterLock，但不同之处在于，前者简化了递归规则以及锁状态的升级和降级规则。 ReaderWriterLockSlim 避免了许多潜在的死锁情况。 另外，ReaderWriterLockSlim 的性能显著优于 ReaderWriterLock。

ReaderWriterLock 用于同步对资源的访问。 在任何给定时间，它都允许对多个线程进行并发读取访问，或对单个线程进行写入访问。 在资源不经常更改的情况下， ReaderWriterLock 与简单的一次锁定（例如 ） Monitor相比，提供更好的吞吐量。

ReaderWriterLock 在大多数访问是读取，而写入不频繁且持续时间短的情况下，效果最佳。 多个读取器交替使用单个编写器，因此读取器和编写器都不会长时间被阻止。

注意

长时间保留读取器锁或编写器锁会耗尽其他线程。 为了获得最佳性能，请考虑重新调整应用程序以最大程度地减少写入持续时间。

线程可以同时持有读取器锁或编写器锁，但不能同时持有两者。 可以使用 UpgradeToWriterLock 和 DowngradeFromWriterLock，而不是为了获取编写器锁而释放读取器锁。

递归锁请求会增加锁上的锁计数。

读取器和编写器分别排队。 当线程释放编写器锁时，此时在读取器队列中等待的所有线程都被授予读取器锁;释放所有这些读取器锁后，写入器队列中等待的下一个线程（如果有）将被授予编写器锁，依此排序。 换句话说， ReaderWriterLock 在读者集合和一个编写器之间交替。

当编写器队列中的线程正在等待释放活动读取器锁时，请求新读取器锁的线程将累积在读取器队列中。 他们的请求未获得授权，即使他们可以与现有读者锁持有者共享并发访问权限;这有助于保护编写器免受读取器的无限期阻塞。

获取锁定 ReaderWriterLock 的大多数方法都接受超时值。 使用超时来避免应用程序中出现死锁。 例如，线程可能会获取一个资源的编写器锁，然后请求另一个资源的读取器锁;同时，另一个线程可能会获取第二个资源的编写器锁，并在第一个资源上请求读取器锁。 除非使用超时，否则线程死锁。

如果超时间隔过期且未授予锁定请求，则 方法通过引发 ApplicationException将控制权返回到调用线程。 线程可以捕获此异常并确定接下来要执行的操作。

超时以毫秒表示。 如果使用 System.TimeSpan 指定超时，则使用的值是 表示 TimeSpan的整毫秒总数。 下表显示了有效的超时值（以毫秒为单位）。

“值”	说明
-1	线程将等待，直到获取锁，而不管它需要多长时间。 对于指定整数超时的方法，可以使用 常量 Infinite 。
0	线程不会等待获取锁。 如果无法立即获取锁，方法将返回。
>0	要等待的毫秒数。

除 -1 外，不允许使用负超时值。 如果指定除 -1 以外的负整数，则改用零的超时值。 (也就是说，如果无法立即获取锁，则方法返回而不等待。) 如果指定 TimeSpan 表示除 -1 以外的负数毫秒的 ， ArgumentOutOfRangeException 则会引发。

构造函数

ReaderWriterLock()

初始化 ReaderWriterLock 类的新实例。

属性

IsReaderLockHeld	获取一个值，该值指示当前线程是否持有读线程锁。
IsWriterLockHeld	获取一个值，该值指示当前线程是否持有写线程锁。
WriterSeqNum	获取当前序列号。

方法

AcquireReaderLock(Int32)	使用一个 Int32 超时值获取读线程锁。
AcquireReaderLock(TimeSpan)	使用一个 TimeSpan 超时值获取读线程锁。
AcquireWriterLock(Int32)	使用一个 Int32 超时值获取写线程锁。
AcquireWriterLock(TimeSpan)	使用一个 TimeSpan 超时值获取写线程锁。
AnyWritersSince(Int32)	指示获取序列号之后是否已将写线程锁授予某个线程。
DowngradeFromWriterLock(LockCookie)	将线程的锁状态还原为调用 UpgradeToWriterLock(Int32) 前的状态。
Equals(Object)	确定指定对象是否等于当前对象。 (继承自 Object)
GetHashCode()	作为默认哈希函数。 (继承自 Object)
GetType()	获取当前实例的 Type。 (继承自 Object)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
ReleaseLock()	释放锁，不管线程获取锁的次数如何。
ReleaseReaderLock()	减少锁计数。
ReleaseWriterLock()	减少写线程锁上的锁计数。
RestoreLock(LockCookie)	将线程的锁状态还原为调用 ReleaseLock() 前的状态。
ToString()	返回表示当前对象的字符串。 (继承自 Object)
UpgradeToWriterLock(Int32)	使用一个 Int32 超时值将读线程锁升级为写线程锁。
UpgradeToWriterLock(TimeSpan)	使用一个 TimeSpan 超时值将读线程锁升级为写线程锁。

线程安全性

此类型是线程安全的。

另请参阅

• 托管线程
• ReaderWriterLock