Bus is always disposed before generic host is stopping hosted services

[mksergiy]

Registering bus.Dispose() in IHostApplicationLifetime.ApplicationStopping causes the bus to be disposed before the generic host stops the hosted services

code from RebusInitializer:

// stopping the bus here will ensure that we've finished executing all message handlers when the container is disposed
stoppingToken.Register(() =>
{
    logger?.LogDebug("Stopping token signaled - disposing bus instance {busInstance}", bus);
    bus.Dispose();
    logger?.LogInformation("Bus instance {busInstance} successfully disposed", bus);
});

When I commented out the registration mentioned above, everything worked fine, including the order of stopping RebusBackgroundService.

[mookid8000]

Hmm actually this might call for giving Rebus the ability to wait for currently executing message handlers to finish - this way, the stopping token above could just set the number of workers to 0 (thus preventing that additional messages are fetched), and then block, waiting for currently executing message handlers to finish.

This bus could then be disposed at a later point in time when everything else has shut down.

I'll run a couple of experiments to see if that would be feasible.