在ASP.NET MVC 3 Action方法中并行运行任务

Question

我有在ASP.NET MVC 3应用程序,返回的建议搜索行动包含和建议标记与给定的关键字:

[HttpPost]
public ActionResult Search(string query, int pg = 0)
{
    var keywords = query.Split(new[] { ' ', ',', ';' }, 
        StringSplitOptions.RemoveEmptyEntries);

    var containing = (from s in _readonlySession.All<Suggestion>()
                      from k in keywords
                      where (s.Text.ToLower().Contains(k.ToLower()))
                      orderby s.Text
                      select s).Distinct();

    var tagged = (from t in _readonlySession.All<Tag>()
                  from s in t.Suggestions
                  from k in keywords
                  where t.Text.ToLower().Contains(k.ToLower())
                  orderby s.Text
                  select s).Distinct();

    var model = new SearchViewModel
    {
        Query = query,
        Containing = containing.ToList(),
        Tagged = tagged.ToList()
    };

    return View(model);
}

我认为containing和tagged查询可以完美并行运行.

同时触发这两个查询的最佳方法是什么,等待结果,并且仅在两个查询完成时返回？

Answer 1

任务Parallels库是您的最佳选择.通过Google获取大量信息,但下面是您的实施可能的样子.

[HttpPost]
public ActionResult Search(string query, int pg = 0)
{
    var keywords = query.Split(new[] { ' ', ',', ';' }, 
        StringSplitOptions.RemoveEmptyEntries);

    IEnumerable containing=null;
    Task t1 = Task.Factory.StartNew(() =>
    {
        containing = (from s in _readonlySession.All<Suggestion>()
                        from k in keywords
                        where (s.Text.ToLower().Contains(k.ToLower()))
                        orderby s.Text
                        select s).Distinct().ToList();

    });

    IEnumerable tagged=null;
    Task t2 = Task.Factory.StartNew(() =>
    {
        var tagged = (from t in _readonlySession.All<Tag>()
                        from s in t.Suggestions
                        from k in keywords
                        where t.Text.ToLower().Contains(k.ToLower())
                        orderby s.Text
                        select s).Distinct().ToList();
    });

    t1.Wait();
    t2.Wait();

    var model = new SearchViewModel
    {
        Query = query,
        Containing = containing.ToList(),
        Tagged = tagged.ToList()
    };

    return View(model);
}

请记住,如果您的应用程序收到大量请求,您可能最好不要异步执行查询 - 消耗2个额外的线程来为一个请求提供服务会使资源远离其他传入请求.如果您拥有大量流量,或者您的硬件不足,这只会是一个问题.