Resolve runs for longer than lifetime

[nmenardg-keeper]

Describe the bug
Using the email-validator lib ( https://github.com/JoshData/python-email-validator/blob/main/email_validator/deliverability.py#L40 ), with a lifetime set to 15s, resolve often runs for over 60 seconds. I'd expect a lifetime of 15s to run for maybe 16s maximum. I didn't test further, my solution on my side is to to use signal to interrupt the resolve (got the idea from https://stackoverflow.com/a/494273 )
I also opened an issue on email-validator: JoshData/python-email-validator#101

To Reproduce
See email-validator implementation. You could try maybe throttling network calls

Context (please complete the following information):

• dnspython version 2.3.0
• Python version 3.8
• OS: Linux (can't disclose specific distro)

[rthalley]

Is it your validate_email_delivery() that is taking more than 60 seconds, or a single call to resolve()? The resolver's lifetime field is the default lifetime for each resolve() invocation. Your validate_email_delivery() code is calling resolve() several times, to get MX, A, AAAA, and TXT. At 15 seconds each, that could be 60 seconds. If you want to impose a lifetime over a set of resolutions, you need to decide how much to give each and supply a lifetime for each invocation.

[nmenardg-keeper]

That's a very good point. I'm not working on that lib so I won't debug more closely, but I'll close this ticket