多线程控制台应用程序中的EF核心内存泄漏

问题描述

我创建了一个小型控制台应用程序，在其中模拟了我在Azure Service Bus消息传递应用程序中使用EF内核的内存泄漏问题。

设置如下：

我从MyContext中的DbContext继承

public class MyContext : DbContext
{
    private readonly Assembly configurationAssembly;

    public MyContext(Assembly configurationAssembly,DbContextOptions dbContextOptions) : base(dbContextOptions)
    {
        this.configurationAssembly = configurationAssembly;
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfigurationsFromAssembly(this.configurationAssembly);
    }
}

我有一个POCO课：

public class Job
{
    public int Id { get; set; }
    public string Applicationcode { get; set; }
}

和一个EntityTypeConfiguration：

public class JobConfig : IEntityTypeConfiguration<Job>
{
    public void Configure(EntityTypeBuilder<Job> builder)
    {
        builder.ToTable("Job_OP");
    }
}

MyContext在OnModelCreating替代（ApplyConfigurationFromAssembly）中使用此配置

最后在程序中，我有以下代码：

class Program
{
    private static IContainer container;
    static void Main(string[] args)
    {
        var builder = new ContainerBuilder(); //Autofac dependency injection

        var dbContextOptionsBuilder = new DbContextOptionsBuilder().UsesqlServer("Data Source=localhost;Initial Catalog=TestEFThreads;Integrated Security=True");

        builder.Register(ctx => new MyContext(
            Assembly.Load("TestEFThreads"),dbContextOptionsBuilder.Options));
        //I tried to use different lifetime scopes here,but EF doesn't like using the same dbContext concurrently in different threads.
        //Currently each resolve instantiates a new MyContext

        container = builder.Build();

        var input = ShowMenu();
        var nrOfSimulatedMessages = 0;
        while (!string.Equals(input,"q",StringComparison.OrdinalIgnoreCase))
        {
            try
            {
                nrOfSimulatedMessages = Convert.ToInt32(input);
                PerformSimulation(maxThreads: 10,nrOfSimulatedMessages);
            }
            catch (Exception e)
            {
                Console.WriteLine($"Incorrect input or exception,{e}");
            }
            input = ShowMenu().ToLower();
        }
    }

    static string ShowMenu()
    {
        Console.WriteLine("Enter number of simulated messages or q to quit");
        return Console.ReadLine();
    }

    private static void PerformSimulation(int maxThreads,int nrOfSimulatedMessages)
    {
        var messageCount = 0;

        var tasks = new Task[maxThreads];

        while (messageCount < nrOfSimulatedMessages)
        {
            for (int i = 0; i < maxThreads && messageCount < nrOfSimulatedMessages; i++)
            {
                Console.WriteLine($"Creating thread {i} for message {messageCount}");
                tasks[i] = new Task(StartProcessing);
                tasks[i].Start();
                messageCount++;
            }
            Console.WriteLine("Waiting for all threads to finish");
            Task.WaitAll(tasks.Where(a=>a !=null).ToArray());
        }
    }

    private static void StartProcessing()
    {
        using (var lifeTime = container.BeginLifetimeScope()) //does not help
        {
            var myContext = container.Resolve<MyContext>();
            var job = myContext.Set<Job>().SingleOrDefault(a => a.Id == 1);
            Console.WriteLine($"Found job with applicationCode {job.Applicationcode}");
            myContext.dispose(); //memory leak even with dispose
        }
    }
}

因此，此应用程序从db进行简单读取，并执行了指定次数，每次都在单独的线程中进行。

当我运行它大约50000个“消息”时，内存会不断增加，这在诊断程序中可以看到。 它似乎没有被垃圾收集。

有人对如何解决此内存泄漏有想法吗？

更新： 它似乎与Autofac依赖项注入有关。 如果我仅使用新的MyContext iso来解决它的内存使用情况就很好。

    private static void StartProcessing()
    {
        var myContext = new MyContext(Assembly.Load("TestEFThreads"),dbContextOptionsBuilder.Options);

        var job = myContext.Set<Job>().SingleOrDefault(a => a.Id == 1);
        Console.WriteLine($"Found job with applicationCode {job.Applicationcode}");
    }

但是我确实需要使用依赖注入。

解决方法

使用外部所有者似乎可以解决问题。

    builder.Register(ctx => new MyContext(
        Assembly.Load("TestEFThreads"),dbContextOptionsBuilder.Options)).ExternallyOwned();