Nhibernate学习之性能改善1

ゞ浴缸里的玫瑰 2021-11-10 04:40 271阅读 0赞

1.学习目标  
    通过几天来大家对Nhiberate的反映，很多人对它的性能非常的担心，本文便着手从最直观的角度和方法中逐步改善nhiberate的性能。改善性能是需要做出很多分析和测试的，本文试图从最表层的对象入手，以后逐渐增加其他方面的性能分析。希望各位看官莫要着急。  
 2. 分析：  
    ISession和ISessionFactory对象的产生，使用，和销毁对性能的影响。   
    ISessionFactory对象是线程安全的，它可以被程序的任意线程所适用，但是创建它的性能开销是比较大的。所以不要频繁创建ISessionFactroy对象  
    ISession对象是非线程安全的，创建它的开销比较小   
    创建一个ISessionFactory对象的主要流程有:  
       ![124rty.JPG][]  
 这期间，包括对多个xml文件的解析和格式验证，验证的过程还包括对对象的反射。这些对性能损失非常大。用dottrace跟踪程序执行，如下  
  ![we5673.JPG][]  
在web应用程序里面，将ISessionFactory对象放到预缓存里面，可以避免频繁创建ISessionFactory对象。如

![None.gif][] using  System;  
![None.gif][] using  System.Data;  
![None.gif][] using  System.Configuration;  
![None.gif][] using  System.Web;  
![None.gif][] using  System.Web.Security;  
![None.gif][] using  System.Web.UI;  
![None.gif][] using  System.Web.UI.WebControls;  
![None.gif][] using  System.Web.UI.WebControls.WebParts;  
![None.gif][] using  System.Web.UI.HtmlControls;  
![None.gif][] using  NHibernate;  
![None.gif][] using  NHibernate.Cfg;  
![None.gif][]  
![None.gif][]  
![None.gif][] namespace  WebApp  
![ExpandedBlockStart.gif][]![ContractedBlock.gif][] ![dot.gif][] \{  
![InBlock.gif][]    public sealed class NHibernateHelper  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]    ![dot.gif][]\{  
![InBlock.gif][]        private const string CurrentSessionKey = "nhibernate.current\_session";  
![InBlock.gif][]        private static readonly ISessionFactory sessionFactory;  
![InBlock.gif][]  
![InBlock.gif][]        static NHibernateHelper()  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            string cfgPath = @"E:\\my project\\nhibernate study\\simle 1\\NHibernateStudy1\\NhibernateSample1\\hibernate.cfg.xml";  
![InBlock.gif][]            sessionFactory = new NHibernate.Cfg.Configuration().Configure(cfgPath).BuildSessionFactory();  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![InBlock.gif][]        public static ISession GetCurrentSession()  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            HttpContext context = HttpContext.Current;  
![InBlock.gif][]            ISession currentSession = context.Items\[CurrentSessionKey\] as ISession;  
![InBlock.gif][]  
![InBlock.gif][]            if (currentSession == null)  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]            ![dot.gif][]\{  
![InBlock.gif][]                currentSession = sessionFactory.OpenSession();  
![InBlock.gif][]                context.Items\[CurrentSessionKey\] = currentSession;  
![ExpandedSubBlockEnd.gif][]            \}  
![InBlock.gif][]  
![InBlock.gif][]            return currentSession;  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![InBlock.gif][]        public static void CloseSession()  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            HttpContext context = HttpContext.Current;  
![InBlock.gif][]            ISession currentSession = context.Items\[CurrentSessionKey\] as ISession;  
![InBlock.gif][]  
![InBlock.gif][]            if (currentSession == null)  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]            ![dot.gif][]\{  
![InBlock.gif][]                // No current session  
![InBlock.gif][]                return;  
![ExpandedSubBlockEnd.gif][]            \}  
![InBlock.gif][]  
![InBlock.gif][]            currentSession.Close();  
![InBlock.gif][]            context.Items.Remove(CurrentSessionKey);  
![ExpandedSubBlockEnd.gif][]        \}  
![InBlock.gif][]  
![InBlock.gif][]        public static void CloseSessionFactory()  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]        ![dot.gif][]\{  
![InBlock.gif][]            if (sessionFactory != null)  
![ExpandedSubBlockStart.gif][]![ContractedSubBlock.gif][]            ![dot.gif][]\{  
![InBlock.gif][]                sessionFactory.Close();  
![ExpandedSubBlockEnd.gif][]            \}  
![ExpandedSubBlockEnd.gif][]        \}  
![ExpandedSubBlockEnd.gif][]    \}  
![InBlock.gif][]  
![ExpandedBlockEnd.gif][]\}   
![None.gif][]

用dottrace跟踪结果为:  
![764fgfg.JPG][]  
从执行时间来看

![None.gif][]     System.Diagnostics.Stopwatch sw  =   new  System.Diagnostics.Stopwatch();  
![None.gif][]            sw.Start();  
![None.gif][]            ISession session  =  NHibernateHelper.GetCurrentSession();  
![None.gif][]            session.Close();  
![None.gif][]            sw.Stop();  
![None.gif][]            Response.Write(sw.ElapsedTicks \+ " <br> " );  
![None.gif][]            sw.Reset();  
![None.gif][]            sw.Start();  
![None.gif][]            session  =  NHibernateHelper.GetCurrentSession();  
![None.gif][]            session.Close();  
![None.gif][]            sw.Stop();  
![None.gif][]            Response.Write(sw.ElapsedTicks  \+   " <br> " );  
![None.gif][]            sw.Reset();  
![None.gif][]            sw.Start();  
![None.gif][]            session  =  NHibernateHelper.GetCurrentSession();  
![None.gif][]            session.Close();  
![None.gif][]            sw.Stop();  
![None.gif][]            Response.Write(sw.ElapsedTicks  \+   " <br> " );

执行结果为:  
![wwd44.JPG][]

转载于:https://www.cnblogs.com/jillzhang/archive/2007/04/01/686079.html

[124rty.JPG]: /images/20211109/06423a289d6e48c497fbf1716a23801a.png
[we5673.JPG]: /images/20211109/e70b82ff8a234700a2f4c5e8ffd61073.png
[None.gif]: /images/20211109/17656d9db30944c083050836ce91466e.png
[ExpandedBlockStart.gif]: https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif
[ContractedBlock.gif]: https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif
[dot.gif]: /images/20211109/cc564b2fd461453baaf7de5b7d053aae.png
[InBlock.gif]: /images/20211109/6b687204207245bd919c43f9bed0aecd.png
[ExpandedSubBlockStart.gif]: https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif
[ContractedSubBlock.gif]: https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif
[ExpandedSubBlockEnd.gif]: /images/20211109/22f8d419cd3c48abad468c9f1041b3ce.png
[ExpandedBlockEnd.gif]: /images/20211109/f07a09828a0f48339dc6675af0db3e64.png
[764fgfg.JPG]: /images/20211109/31001236c820434bbc504a1ca3bdb600.png
[wwd44.JPG]: /images/20211109/dddedaef4e1f4d06853ac5cce8fb5b1c.png