优化EF Code First第一次请求速度

由于EF Code First模式没有模型文件，所以很多一次请求的时候速度比较慢，EF需要将对应的数据库映射关系加载到内存里面，往后请求就比较快。可以通过在程序初始化的时候增加一段代码来优化EF第一次执行的速度，具体代码如下

//EF暖机操作
using (CompanyContext dbContext = new CompanyContext())
{
  var objectContext =((IObjectContextAdapter)dbContext).ObjectContext;

 var mappingCollection =
             (StorageMappingItemCollection)objectContext.MetadataWorkspace.GetItemCollection(DataSpace.CSSpace);
mappingCollection.GenerateViews(new List<EdmSchemaError>());
}

控制台项目则把上面一段代码放在Main方法中即可，在需要调用的方法之前执行。

 static void Main(string[] args)
     {
            //EF暖机操作
            using (CompanyContext dbContext = new CompanyContext())
            {
                var objectContext = ((IObjectContextAdapter)dbContext).ObjectContext;

                var mappingCollection =
                    (StorageMappingItemCollection)objectContext.MetadataWorkspace.GetItemCollection(DataSpace.CSSpace);
                mappingCollection.GenerateViews(new List<EdmSchemaError>());
            }

            Stopwatch sw = new Stopwatch();

            sw.Start();
            using (DbContext dbContext = new CompanyContext())
            {
                foreach (var entity in dbContext.Set<UserInfo>())
                {
                    Console.WriteLine(entity.UserName);
                }
            }

            sw.Stop();

            Console.WriteLine(sw.ElapsedMilliseconds);

            Console.ReadKey();
        }

如果是Asp.Net WebForm或者MVC项目则把上述代码加载Application_Start方法中即可，即在网站启动时候就进行映射关系的加载

WebForm项目

 protected void Application_Start(object sender, EventArgs e)
  {
            //EF暖机代码
            using (CompanyContext dbContext = new CompanyContext())
            {
                var objectContext = ((IObjectContextAdapter)dbContext).ObjectContext;

                var mappingCollection =
                    (StorageMappingItemCollection)objectContext.MetadataWorkspace.GetItemCollection(DataSpace.CSSpace);
                mappingCollection.GenerateViews(new List<EdmSchemaError>());
            }
 }

MVC项目

 public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();

            WebApiConfig.Register(GlobalConfiguration.Configuration);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);

            //EF优化代码
            using (CompanyContext dbContext = new CompanyContext())
            {
                var objectContext = ((IObjectContextAdapter)dbContext).ObjectContext;

                var mappintCollection = (StorageMappingItemCollection)objectContext.MetadataWorkspace.GetItemCollection(DataSpace.CSSpace);

                mappintCollection.GenerateViews(new List<EdmSchemaError>());
            }
        }
    }

如果是WCF服务寄宿在IIS中的项目，则需要在Web宿主种增加Global.asax配置文件，并在Application_Start方法中加入上述优化代码即可

 protected void Application_Start(object sender, EventArgs e)
        {
            //EF暖机操作
            using (CompanyContext dbContext = new CompanyContext())
            {
                var objectContext = ((IObjectContextAdapter)dbContext).ObjectContext;
                var mappintCollection =
                    (StorageMappingItemCollection)objectContext.MetadataWorkspace.GetItemCollection(DataSpace.CSSpace);
                mappintCollection.GenerateViews(new List<EdmSchemaError>());
            }
        }

对比效果如下

优化前的效果，耗时3281毫秒

优化后的效果，耗时130毫秒