Forces garbage collection from generation zero through a specified generation.

[Visual Basic]
Overloads Public Shared Sub Collect( _
   ByVal generation As Integer _
)
[C#]
public static void Collect(
 int generation
);
[C++]
public: static void Collect(
 int generation
);
[JScript]
public static function Collect(
   generation : int
);

Parameters

generation

The maximum garbage-collected generation.

Exceptions

Remarks

Use this method to attempt to reclaim memory that is inaccessible. However, it does not guarantee that all inaccessible memory in the specified generation is reclaimed.

If object aging is implemented, the garbage collector does not collect objects with a generation number higher than the specified generation. If object aging is not implemented, the garbage collector considers all objects during the garbage collection.

Use the MaxGeneration property to determine the maximum valid value of generation.

To have the garbage collector consider all objects regardless of their generation, use the version of this method that takes no arguments.

Example

[Visual Basic] 
Imports System

Namespace GCCollectInt_Example
    Class MyGCCollectClass
        Private maxGarbage As Long = 10000

        Public Shared Sub Main()
            Dim myGCCol As New MyGCCollectClass

            'Determine the maximum number of generations the system
            'garbage collector currently supports.
            Console.WriteLine("The highest generation is {0}", GC.MaxGeneration)

            myGCCol.MakeSomeGarbage()

            'Determine which generation myGCCol object is stored in.
            Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol))

            'Determine the best available approximation of the number 
            'of bytes currently allocated in managed memory.
            Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(False))

            'Perform a collection of generation 0 only.
            GC.Collect(0)

            'Determine which generation myGCCol object is stored in.
            Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol))

            Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(False))

            'Perform a collection of generation 2 only.
            GC.Collect(2)

            'Determine which generation myGCCol object is stored in.
            Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol))
            Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(False))
            Console.Read()

        End Sub


        Sub MakeSomeGarbage()
            Dim vt As Version

            Dim i As Integer
            For i = 0 To maxGarbage - 1
                'Create objects and release them to fill up memory
                'with unused objects.
                vt = New Version
            Next i
        End Sub
    End Class
End Namespace

[C#] 
using System;

namespace GCCollectIntExample
{
    class MyGCCollectClass
    {
        private const long maxGarbage = 1000;
      
        static void Main()
        {
            MyGCCollectClass myGCCol = new MyGCCollectClass();

            // Determine the maximum number of generations the system
        // garbage collector currently supports.
            Console.WriteLine("The highest generation is {0}", GC.MaxGeneration);
            
            myGCCol.MakeSomeGarbage();

            // Determine which generation myGCCol object is stored in.
            Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol));
            
            // Determine the best available approximation of the number 
        // of bytes currently allocated in managed memory.
            Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(false));
            
            // Perform a collection of generation 0 only.
            GC.Collect(0);
            
            // Determine which generation myGCCol object is stored in.
            Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol));
            
            Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(false));
            
            // Perform a collection of generation 2 only.
            GC.Collect(2);
            
            // Determine which generation myGCCol object is stored in.
            Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol));
            Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(false));
            Console.Read();
        }

        void MakeSomeGarbage()
        {
            Version vt;

            for(int i = 0; i < maxGarbage; i++)
            {
                // Create objects and release them to fill up memory
        // with unused objects.
                vt = new Version();
            }
        }
    }
}

[C++] 
#using <mscorlib.dll>

using namespace System;

const long  maxGarbage = 1000;

__gc class MyGCCollectClass {
public:
   void MakeSomeGarbage() {
      Version* vt;
      for (int i = 0; i < maxGarbage; i++) {
         // Create objects and release them to fill up memory
         // with unused objects.
         vt = new Version();
      }
   }
};

int main() {
   MyGCCollectClass* myGCCol = new MyGCCollectClass();

   // Determine the maximum number of generations the system
   // garbage collector currently supports.
   Console::WriteLine(S"The highest generation is {0}", __box(GC::MaxGeneration));

   myGCCol->MakeSomeGarbage();

   // Determine which generation myGCCol object is stored in.
   Console::WriteLine(S"Generation: {0}", __box(GC::GetGeneration(myGCCol)));

   // Determine the best available approximation of the number
   // of bytes currently allocated in managed memory.
   Console::WriteLine(S"Total Memory: {0}", __box(GC::GetTotalMemory(false)));

   // Perform a collection of generation 0 only.
   GC::Collect(0);

   // Determine which generation myGCCol object is stored in.
   Console::WriteLine(S"Generation: {0}", __box(GC::GetGeneration(myGCCol)));

   Console::WriteLine(S"Total Memory: {0}", __box(GC::GetTotalMemory(false)));

   // Perform a collection of generation 2 only.
   GC::Collect(2);

   // Determine which generation myGCCol object is stored in.
   Console::WriteLine(S"Generation: {0}", __box(GC::GetGeneration(myGCCol)));
   Console::WriteLine(S"Total Memory: {0}", __box(GC::GetTotalMemory(false)));
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

GC Class | GC Members | System Namespace | GC.Collect Overload List