IServiceProvider garbage collection / disposal

Question

I was trying to debug a memory leak in my app (see related question) and have encountered a smilingly wrong behavior.

In this code (simplified snippet, of course):

    while (true)
    {
        using (var context = _serviceProvider.GetRequiredService<IDataContext>())
        {
            Console.WriteLine("Hello");
        }
    }

Memory consumption grows rapidly.

If I comment out service spawn, memory consumption is stable.

    while (true)
    {
        // using (var context = _serviceProvider.GetRequiredService<IDataContext>())
        // {
            Console.WriteLine("Hello");
        // }
    }

Service was registered as transient.

My understanding is that using statement is responsible for disposing a service. var context is created in the scope of while and should be destroyed when new iteration begins.

My first thought was that GC just does not do its job frequently enough, but does not frequency increase when amount of consumed memory increases?

Why am I wrong?

Answer 1

After days of fighting the problem, I finally derived the answer. In short, the issue is that Microsoft DI container does not dispose transient services, it keeps references on them.

Here is the corresponding issue on github.

The developers do not plan to fix it since the cost (complexity and hackiness) of fixing overweighs the benefits.

Suggested workaround is using scoped service instead of the transient one.

Here is an example code, see more in issue.

using (var scope = serviceProvider.CreateScope())
using (var context = scope.ServiceProvider.GetRequiredService<IDataContext>())
{ ... }