winform 关闭窗体 释放内存

private void formclosed
        {
            FlushMemory();
        }

[DllImport("kernel32.dll")]
        private static extern bool SetProcessWorkingSetSize(IntPtr process, int minSize, int maxSize);
        private static void FlushMemory()
        {
            GC.Collect();
            GC.WaitForPendingFinalizers();
            if (Environment.OSVersion.Platform == PlatformID.Win32NT)
                SetProcessWorkingSetSize(Process.GetCurrentProcess().Handle, -1, -1);
        }