SSLProtocol stalled during handshake

[hynek]

• uvloop version:

0.10.0, doesn’t happen with 0.9.1

• Python version:

3.6.5

• Platform:

Ubuntu Xenial/Docker

• Can you reproduce the bug with PYTHONASYNCIODEBUG in env?:

Yes, but I get no additional output.

---

I have to communicate with a super-slow endpoint and since 0.10.0, the connection doesn’t go thru and aborts before the timeout I specify.

Stdout gets a string like: <uvloop.loop.SSLProtocol object at 0x7f227a1a1048> stalled during handshake. It seems like there’s a second timeout in play? I did measure the handshake by hand I would guess something around 5s.

Downgrading back to 0.9.1 fixes the problem.

P.S. Bonus bug I cannot handily reproduce: sometimes I saw an AttributeError about errno not being on CertificateError or something like that.

[1st1]

In 0.10.0 there's a 10 seconds timeout for the handshake operation. Is your endpoint slower than that?

It's also a default timeout for handshake in asyncio 3.7, although it's configurable via the ssl_handshake_timeout parameter to create_connection and create_server (the parameter isn't yet backported to uvloop). Do you feel that 10 seconds is not enough?

P.S. Bonus bug I cannot handily reproduce: sometimes I saw an AttributeError about errno not being on CertificateError or something like that.

That means asyncio 3.7 has this bug too. Will take a look.

[hynek]

Do you feel that 10 seconds is not enough?

How do you think I found out? ;) 10s is wayyy to short once you have to communicate from/to Africa or Asia. I spent a month in Cape Town and learned this the hard way.

In this case I couldn’t communicate with a server in India. If this goes into 3.7 there’s gonna be a lot of...reports. :D

[hynek]

It would also be great if we could do something about the output btw.

[1st1]

What default timeout would you suggest?

It would also be great if we could do something about the output btw.

You mean the errno/CertificateError error? Or the "... stalled during handshake" error message?

[hynek]

What default timeout would you suggest

No clue! Check what browsers or Java or Go do maybe?

You mean the errno/CertificateError error? Or the "... stalled during handshake" error message?

Both ✨

Although the errno thing is a lot more severe.

[hynek]

(I can live with it staying at 10s btw as long as you give me a knob to turn. :))

[1st1]

(a PR to CPython to fix this: python/cpython#7321)

[1st1]

Fixed in v0.10.1. Please try it ;)

[hynek]

Happy to report I can connect to India again. :)