并行程序的一点注意事项

    这几天无事,把自己以前写的一套CMS程序拿来改改,想用parallel.foreach来提高生成HTML的效率

    模版解析类就没动,直接把以前的for循环改成parallel.foreach,就出现了未将对象引用设置到对象实例的错误,查找了半天,才发现问题出现在模版解析类的加载模版里

 

public void Load()
        {
            try
            {
                string CacheKey = "cache_" + tempPath;
                object objModel = CacheHelper.GetCache(CacheKey);
                if (objModel == null)
                {
                    using (StreamReader sr = new StreamReader(HttpContext.Current.Server.MapPath(tempPath))
                    {
                        tempContext = sr.ReadToEnd();
                        CacheDependency dep = new CacheDependency(HttpContext.Current.Server.MapPath(tempPath), DateTime.Now);
                        CacheHelper.SetCache(CacheKey, tempContext as object, dep, DateTime.Now.AddMinutes(30), TimeSpan.Zero);
                    }
                }
            }
            catch (UserException ex)
            {
                throw new UserException(ex.ToString());
            }
        }

 

在多线程里面使用HttpContext.Current,HttpContext.Current得到是null.

 

 

StreamReader sr = new StreamReader(HttpContext.Current.Server.MapPath(tempPath))
//修改成下面就行
StreamReader sr = new StreamReader(System.AppDomain.CurrentDomain.BaseDirectory.ToString() + tempPath)

 

另在附上一个DZ里的解决办法

public static string MapPath(string strPath)

{
  if (HttpContext.Current != null)
  {
  return HttpContext.Current.Server.MapPath(strPath);
  }
  else //非web程序引用
  {
  strPath = strPath.Replace("/", "\\");
  if (strPath.StartsWith("\\"))
  {
  //strPath = strPath.Substring(strPath.IndexOf('\\', 1)).TrimStart('\\');
  strPath = strPath.TrimStart('\\');
  }
  return System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, strPath);
  }
  }