NHibernate性能的思考

“省事的活多半效率不高”，对编程来说，很多时候适用。NHibernate省却我们写Sql语句、存储过程，且数据库的移植又是相当方便，效率估计有一些影响。

那影响有多大呢？

为此我利用一个现有的WebService，试图去比较使用NHibernate和直接使用SqlClient之间的性能差异。

private ISessionFactory _sessions;
public void Configure()
{
    Configuration cfg = new Configuration();
    cfg.SetProperty("hibernate.connection.provider","NHibernate.Connection.DriverConnectionProvider");
    cfg.SetProperty("hibernate.dialect","NHibernate.Dialect.MsSql2000Dialect");
    cfg.SetProperty("hibernate.connection.driver_class","NHibernate.Driver.SqlClientDriver");
    cfg.SetProperty("hibernate.connection.connection_string","Server=localhost;initial catalog=Supercargo;user id=sa;password=network");

    cfg.AddClass(typeof(Supercargo.Batch));
    cfg.AddClass(typeof(Supercargo.Product));
    cfg.AddClass(typeof(Supercargo.BatchItem));
    this._sessions = cfg.BuildSessionFactory();
}

每一次的都从头到尾执行一次

this.Configure();
ISession session = _sessions.OpenSession();
ITransaction transaction = session.BeginTransaction();

session.Save(product1);
transaction.Commit();
session.Close();

SqlClient也一样从头到尾

SqlConnection connect = new SqlConnection("Server=localhost;initial"); 
try
{
    connect.Open();
    
    SqlCommand cmd = new SqlCommand(sql,connect);
    cmd.ExecuteNonQuery();
}
catch(Exception ee)
{
    str= string.Format("语句：{0} \r\n错误：{1}",sql, ee.Message);
}
connect.Close();

执行100次的以上操作，NHibernate用了近6秒，直接使用SqlClient却用了不到2秒。NHibernate真的如此不济？

稍作思考，将NHibernate的过程分解了一下。首先使用一个类包装一下Configure

/**//// <summary>
/// DbConfigure 的摘要说明。
/// </summary>
public class DbConfigure
{
    /**//// <summary>
    /// 获取 Web应用程序的当前配置
    /// </summary>
    public static DbConfigure CurrentConnect
    {
        get
        {
            DbConfigure con = null;
            object obj = System.Web.HttpContext.Current.Application["Connect"];
            if(obj == null)
            {
                con = new DbConfigure();                    
                System.Web.HttpContext.Current.Application["Connect"] = con;
            }
            else
                con = (DbConfigure)obj;

            return con;
        }
    }

    /**//// <summary>
    /// 构造函数
    /// </summary>
    public DbConfigure()
    {                
        this.configure();        
    }

    /**//// <summary>
    /// 打开连接。
    /// </summary>
    /// <returns></returns>
    public ConnectSession OpenSession()
    {
        return new ConnectSession(this._sessions.OpenSession());
    }                        

    private ISessionFactory _sessions;
    private void configure()
    {        
        Configuration cfg = new Configuration();
        cfg.SetProperty("hibernate.connection.provider","NHibernate.Connection.DriverConnectionProvider");
        cfg.SetProperty("hibernate.dialect","NHibernate.Dialect.MsSql2000Dialect");
        cfg.SetProperty("hibernate.connection.driver_class","NHibernate.Driver.SqlClientDriver");
        cfg.SetProperty("hibernate.connection.connection_string","Server=localhost;initial catalog=Superca");
        cfg.AddClass(typeof(SD.Supercargo.Batch));
        cfg.AddClass(typeof(SD.Supercargo.Product));
        cfg.AddClass(typeof(SD.Supercargo.BatchItem));            
        this._sessions = cfg.BuildSessionFactory();                
    }        
}

也将ISession简单的封装到ConnectSession中

    /**//// <summary>
    /// ConnectSession 的摘要说明。
    /// </summary>
    public class ConnectSession
    {
        public ConnectSession(ISession pSession)
        {            
            this.mDbSession = pSession;
        }

        public void Close()
        {
            this.mDbSession.Close();
        }

        public void BeginTransaction()
        {
            this.mTransaction = this.mDbSession.BeginTransaction();
        }

        public void CommitTransaction()
        {
            this.mTransaction.Commit();
        }

        public void Update(object obj)
        {
            this.DbSession.Update(obj);
        }

        public void Save(object obj)
        {
            this.DbSession.Save(obj);
        }

        public void SaveOrUpdate(object obj)
        {
            this.DbSession.SaveOrUpdate(obj);
        }

        private ITransaction mTransaction;
        /**//// <summary>
        /// 设置、获取Transaction
        /// </summary>
        public ITransaction Transaction
        {
            get
            {
                if(this.mTransaction == null)
                    this.mTransaction = this.mDbSession.BeginTransaction();
                return this.mTransaction;
            }            
        }
        private ISession mDbSession;
        /**//// <summary>
        /// 获取DbSession
        /// </summary>
        public ISession DbSession
        {
            get{return this.mDbSession;}            
            set{this.mDbSession = value;}
        }
    }

测试过程只执行以下几步

DbConfigure con = DbConfigure.CurrentConnect;
ConnectSession connect = con.OpenSession();

ProductLocator prdLoc = new ProductLocator(connect.DbSession);
Product prd = new Product();
//一些赋值操作
connect.BeginTransaction();
prdLoc.Update(prd);
connect.CommitTransaction();
connect.Close();

NHibernate的成绩一下子提高到只需1.3秒多些，只稍慢于SqlClient的1.2秒，同样是操作100次。代码上的差异主要是用Application保存DbConfigure，Web应用程序只主要在启动的时候执行DbConfigure的Configure方法

public static DbConfigure CurrentConnect
{
    get
    {
        DbConfigure con = null;
        object obj = System.Web.HttpContext.Current.Application["Connect"];
        if(obj == null)
        {
            con = new DbConfigure();                    
            System.Web.HttpContext.Current.Application["Connect"] = con;
        }
        else
            con = (DbConfigure)obj;

        return con;
    }
}

当然对于windows应用程序就可以省下这个心了。看来NHibernate的是相当值得使用!