Question

我正在尝试对NorthWind数据库进行一些分析，以测试性能问题。

我的查询如何运行并永久挂起。奇怪的是，当我们说4个CONCURRENT_CALLS

时，一切正常

我正在使用SQL Server 2016运行EF6

我知道实体框架在同一个上下文中对异步请求不起作用，所以我们在每个线程中产生一个新的上下文。

class Program
{
    public static int MAX_IO_THREADS = 2000;
    public static int MIN_IO_THREADS = 1000;
    public static int CONCURRENT_CALLS = 10;

    static void Main(string[] args)
    {
        ConfigureThreadPool();
        WarmUpContexts();

        ProfileAction();
        Console.ReadKey();
    }

    protected static void ProfileAction()
    {
        var callRange = Enumerable.Range(0, CONCURRENT_CALLS);

        var stopwatch = new Stopwatch();
        stopwatch.Start();

        var results = new ConcurrentDictionary<int, string>();

        Parallel.ForEach(callRange, i =>
        {
            var callSw = new Stopwatch();
            callSw.Start();
            var result = RunTest().Result;
            callSw.Stop();

            results.TryAdd(i, $"Call Index: {i} took {callSw.ElapsedMilliseconds} milliseconds to complete");

        });

        stopwatch.Stop();
        var milliseconds = stopwatch.ElapsedMilliseconds;

        foreach (var result in results.OrderBy(x => x.Key))
        {
            Console.WriteLine(result);
        }

        Console.WriteLine("Total Time " + milliseconds);
    }

    public static void ConfigureThreadPool()
    {
        ThreadPool.GetMinThreads(out var defaultMinWorkerCount, out var _);
        ThreadPool.GetMaxThreads(out var defaultMaxWorkerCount, out var _);

        ThreadPool.SetMaxThreads(defaultMaxWorkerCount, MAX_IO_THREADS);
        var successMin = ThreadPool.SetMinThreads(defaultMinWorkerCount, MIN_IO_THREADS);
    }

    static void WarmUpContexts()
    {
        using (var stagingContext = new NORTHWNDEntities())
        {
            stagingContext.Employees.First();
        }
    }


    static async Task<int> RunTest()
    {
        using (var context = new NORTHWNDEntities())
        {
            var employees = await context.Employees.ToArrayAsync();
            return employees.Length;
        }
    }
}

我也尝试修改gcServer以更好地使用并发性

<runtime>
  <gcServer enabled="true" />
</runtime>

我修改了连接字符串以增加最小池大小

综合安全=真; pooling = true;最小池大小= 100;

一切都永远挂起。当我在sql上运行sp_whoisactive时，我可以看到我的用户上有（636ms）ASYNC_NETWORK_IO被捕获，并且一次只显示一个连接。

这是entityframework中的错误吗？

EntityFramework 6永远挂起并发Query

0 个答案: