SmtpConnection: fix Socket not getting Disposed when LingerState cannot be set.

[tmds]

Fixes https://github.com/dotnet/corefx/issues/40711

[tmds]

@stephentoub should I change the PR so we can figure out what exact exception gets thrown here? Or do we keep the general catch?

[scalablecory]

My preference would be to catch the most specific exception possible, though the risk here is admittedly minimal.

[davidsh]

Is the exception something other than derived from System.Exception? Otherwise, why not just write catch (Exception) ?

But I agree it is useful to understand what's going on here. I would expect the exception is probably a SocketException.

[stephentoub]

should I change the PR so we can figure out what exact exception gets thrown here?

My preference is to catch just the exception types we expect. Thanks.

[tmds]

@scalablecory @davidsh @scalablecory I have to change the PR so we know what exception gets thrown here.

I'll revert this try-catch, and also remove the general try-catch in SmtpClient.Abort. That should surface the exception.

We can give it a couple of test runs here. But since the issue doesn't happen often, probably we'll have to merge and wait for some time until it shows up in CI.

[scalablecory]

This change looks fine. How reasonable would it be to write a test that exercises this?

[scalablecory]

My preference would be to catch the most specific exception possible, though the risk here is admittedly minimal.

[tmds]

I've updated the PR so instead of hanging, we should see the exception show up in CI now.
I'm also curious what exception gets thrown here.

How reasonable would it be to write a test that exercises this?

Though not a 100% test, the occasional failures in CI mean there is some coverage.
Maybe we learn something from the exception type on how to make it more reproducible.

[tmds]

@dotnet/ncl This is good to merge, and will help surface the exception we should catch.

[ghost]

Hello @stephentoub!

Because this pull request has the auto-merge label, I will be glad to assist with helping to merge this pull request once all check-in policies pass.

p.s. you can customize the way I help with merging this pull request, such as holding this pull request until a specific person approves. Simply @mention me (@msftbot) and give me an instruction to get started! Learn more here.