Autofac - resolving dependencies in multi thread environment

To give each thread its own lifetime scope, you just need to register your IsolatedLifetimeScopeFactory as SingleInstance. This will solve your concerns 2) and 3)

[TestMethod]public void MyTestMethod(){    var cb = new ContainerBuilder();    cb.RegisterGeneric(typeof(IsolatedLifetimeScopeFactory<>))        .SingleInstance();    var container = cb.Build();    using (var scope1 = container.BeginLifetimeScope("scope1"))    using (var scope2 = scope1.BeginLifetimeScope("scope2"))    {        var factory = scope2.Resolve<IsolatedLifetimeScopeFactory<object>>();        var tag = factory._scope.Tag; // made _scope public for testing purposes        Assert.AreNotEqual("scope1", tag);        Assert.AreNotEqual("scope2", tag);        // This particular string "root" is probably not guaranteed behavior, but        // being in the root scope is guaranteed for SingleInstance registrations.        Assert.AreEqual("root", tag);    }}

Your concern 1) could be solved by using a different abstraction. For example, you could add this to the IsolatedLifetimeScopeFactory

public Autofac.Features.OwnedInstances.Owned<TA> Create(){    return _scope.Resolve<Autofac.Features.OwnedInstances.Owned<TA>>();}

And you could hide Owned behind an abstraction if you really wanted to, although I would say that's overkill.