日期:2014-05-20  浏览次数:20882 次

非托管资源占用内存的大小,GC 知道吗?
我有一个 C++/CLI 对象。形如:

C# code


public ref class DStructure
{
private:
    double* array;

protected:
    !DStructure()
    {
        delete[] array;
    }

public:
    DStructure()
    {
        array = new double[1000];
    }

    ~DStructure()
    {
        delete[] array;
    }
};




当我这样运行的时候,内存不断泄漏,然后崩溃了。

C# code


while(true)
{
    DStructure^ ds = gcnew DStructure();
}




但是我这样运行的时候,程序就跑得好好的,不会崩溃,没有泄漏。

C# code


while(true)
{
    DStructure^ ds = gcnew DStructure();
    GC::Collect();
}




这里我不明白的是,在第一种情况下,内存占满后,GC 为什么不会去执行回收,而是坐看着内存爆掉呢?是不是内部它是用“总内存大小 - 托管对象占用内存大小”来计算剩余内存的,所以它看不到非托管的部分?请各位大大赐教~


------解决方案--------------------
学习。
------解决方案--------------------
不行.net framwork不知道非托管资源。

可以实现IDisposable 接口

C# code

using System;
using System.ComponentModel;

// The following example demonstrates how to create
// a resource class that implements the IDisposable interface
// and the IDisposable.Dispose method.

public class DisposeExample
{
    // A base class that implements IDisposable.
    // By implementing IDisposable, you are announcing that
    // instances of this type allocate scarce resources.
    public class MyResource: IDisposable
    {
        // Pointer to an external unmanaged resource.
        private IntPtr handle;
        // Other managed resource this class uses.
        private Component component = new Component();
        // Track whether Dispose has been called.
        private bool disposed = false;

        // The class constructor.
        public MyResource(IntPtr handle)
        {
            this.handle = handle;
        }

        // Implement IDisposable.
        // Do not make this method virtual.
        // A derived class should not be able to override this method.
        public void Dispose()
        {
            Dispose(true);
            // This object will be cleaned up by the Dispose method.
            // Therefore, you should call GC.SupressFinalize to
            // take this object off the finalization queue
            // and prevent finalization code for this object
            // from executing a second time.
            GC.SuppressFinalize(this);
        }

        // Dispose(bool disposing) executes in two distinct scenarios.
        // If disposing equals true, the method has been called directly
        // or indirectly by a user's code. Managed and unmanaged resources
        // can be disposed.
        // If disposing equals false, the method has been called by the
        // runtime from inside the finalizer and you should not reference
        // other objects. Only unmanaged resources can be disposed.
        protected virtual void Dispose(bool disposing)
        {
            // Check to see if Dispose has already been called.
            if(!this.disposed)
            {
                // If disposing equals true, dispose all managed
                // and unmanaged resources.
                if(disposing)
                {
                    // Dispose managed resources.
                    component.Dispose();
                }

                // Call the appropriate methods to clean up
                // unmanaged resources here.
                // If disposing is false,
                // only the following code is executed.
                CloseHandle(handle);
                handle = IntPtr.Zero;

                // Note disposing has been done.
                disposed = true;

            }
        }

        // Use interop to call the method necessary
        // to clean up the unmanaged resource.
        [System.Runtime.InteropServices.DllImport("Kernel32")]
        private extern static Boolean CloseHandle(IntPtr handle);

        // Use C# destructor syntax for finalization code.
        // This destructor will run only if the Dispose method
        // does not get called.
        // It gives your base class the opportunity to finalize.
        // Do not provide destructors in types derived from this class.
        ~MyResource()
        {
            // Do not re-create Dispose clean-up code here.
            // Calling Dispose(false) is optimal in terms of
            // readability and maintainability.
            Dispose(false);
        }
    }
    public static void Main()
    {
        // Insert code here to create
        // and use the MyResource object.
    }
}