IAsyncDisposable support

[yfakariya]

As described .NET documentation, developers expect that services (and function instances) should be disposed even when they only implement IAsyncDisposable. In fact, IServiceProvider
created from Microsoft.Extensions.DependencyInjection.ServiceCollection handles IAsyncDisposable, but Azure Function runtime does not. It leads resource leaks caused by objects which only implement IAsyncDisposable, including ServiceBusSender and ServiceBusReceiver of the Azure ServcieBus, they eventually causes receive link exhausion.

This issue is same as #2870, which was closed as "completed" but it was not solved.

Repro steps

1. Implement IAsyncDisposable for your function class or your service class.
2. Run function. DisposeAsync() of function isntances, transient services, and scoped services never be called.
3. Shutdown function. DisposeAsync() of singleton services never be called.

Expected behavior

If functions and services implement IAsyncDisposable, their DisposeAsync() will be called in end of their lifetime.
If they also implement IDisposable, IAsyncDisposable.DisposeAsync() should be preferred.

Actual behavior

DisposeAsync() never be called.

Known workarounds

• Avoid to store IAsyncDisposable objects to fields of function instances and their dependencies.
  • Note that singleton is not workaround because their DisposeAsync() should be called in graceful shutdown.
• Use isolated worker for services. As far as I saw, isolated worker never dispose service instance even it implement IDisposable, so it is incomplete workaround.

Related information

• Package version: Microsoft.NET.Sdk.Functions: 4.2.0

As far as I saw, following methods should be fixed. I am ready to create PR if my assumption is right.

• Implement IAsyncDisposable.DisposeAsync to:
  *Scope
  * Also fix TrackDisposable to record IAsyncDisposable
  • Container for singleton services disposing async.
  • ScopedResolver
  • JobHostServiceProvider
  • ScopedServiceProvider
  • ServiceScope
  • FunctionInstance
  • ParameterHelper
• Call AsyncDispose() in:
  • IAsyncDisposable.DisposeAsync() methods described above.
  • FunctionExecutor

There are many DI related classes in azure-functions-host repo, so it is OK to post issue if needed.

[bhagyshricompany]

Thanks for reporting pls share the app name,region,invoction id etc.

[yfakariya]

I think it is not Azure resource specific. Is the actual Azure resource required to report SDK issue?