Hi Florian,

"pelzflorian (Florian Pelz)" <pelzflorian@pelzflorian.de> skribis:

> On Tue, Apr 20, 2021 at 03:21:13AM +0200, pelzflorian (Florian Pelz) wrote:
>> > git revert be5a75ebb5988b87b2392e2113f6590f353dd6cd
>
> It seems this is the bad commit.  Downloading the enlightenment
> substitute got stuck and after a few minutes displayed the usual TLS
> error.

Note that on master there have been changes in this area since this
commit, in particular 20c08a8a45d0f137ead7c05e720456b2aea44402.

I assume the error we’re after is still this one:

>>    |    substitute: updating substitutes from 'https://ci.guix.gnu.org'... 0.0%guix substitute: error: TSL error in procedure 'write_to_session_port': Resource temporarily unavailable, try again.

I believe the attached patch “addresses” this problem.

Now, I’m a bit skeptical: the error above is GNUTLS_E_AGAIN, which
happens if sendmsg(2) returns EAGAIN, which supposedly only happens on
datagram (UDP) sockets or on non-blocking sockets, neither of which
applies here.

This change should be safe, though since I’m not sure why we’re getting
EAGAIN in the first place, I wonder what could happen (infinite loop?).

Could you give it a try?

Can you reproduce the substitute issue in a simpler environment?
For instance, by running:

  rm -rf ~/.cache/guix/substitute/
  ./pre-inst-env guix weather $(guix package -A |head -2000 |cut -f1) 

This makes 2000 pipelined GETs to https://ci.guix.gnu.org, which is
probably similar to what you observe during system installation.

Thanks for the thorough debugging and bisecting, as always!

Ludo’.