Bug#978671: apt http transport gets stuck after package download

[Ivan Babrou <ivan@ivan.computer>]

On Tue, Dec 29, 2020 at 1:27 PM Ivan Babrou <debian-bugs@ivan.computer> wrote:
>
> Package: apt
> Version: 1.8.2.1
> Severity: normal
> Tags: patch
>
> Dear Maintainer,
>
> On Debian Buster we're seeing 30s timeouts when downloading
> a particular set of debian packages from an internal repo:
>
> ```
> $ time apt-get download -y rubygem-stud rubygem-mustache rubygem-insist rubygem-pleaserun rubygem-fpm
> ...
> Fetched 451 kB in 30s (15.0 kB/s)
>
> real    0m31.022s
> user    0m0.923s
> sys     0m0.080s
> ```
>
> The issue is fixed in the following commit in apt 2.1.9:
>
> ```
> commit 08f05aa8beb58fa32485e2087eb21a9f3cb267bb
> Author: Julian Andres Klode <julian.klode@canonical.com>
> Date:   Mon Jun 29 14:03:21 2020 +0200
>
>     http: Redesign reading of pending data
>
>     Instead of reading the data early, disable the timeout for the
>     select() call and read the data later. Also, change Read() to
>     call only once to drain the buffer in such instances.
>
>     We could optimize this to call read() multiple times if there
>     is also pending stuff on the socket, but that it slightly more
>     complex and should not provide any benefits.
> ```
>
> Please consider backporting this into Debian Buster,
> as it fixes the problem and the patch itself applies cleanly.
>
> -- System Information:
> Debian Release: 10.6
>   APT prefers stable-updates
>   APT policy: (500, 'stable-updates'), (500, 'stable')
> Architecture: amd64 (x86_64)
>
> Kernel: Linux 5.4.70
> Kernel taint flags: TAINT_OOT_MODULE
> Locale: LANG=C, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE=C (charmap=UTF-8)
> Shell: /bin/sh linked to /bin/dash
> Init: unable to detect
>
> Versions of packages apt depends on:
> ii  adduser                 3.118
> ii  debian-archive-keyring  2019.1
> ii  gpgv                    2.2.12-1+deb10u1
> ii  libapt-pkg5.0           1.8.2.1
> ii  libc6                   2.28-10
> ii  libgcc1                 1:8.3.0-6
> ii  libgnutls30             3.6.7-4+deb10u5
> ii  libseccomp2             2.5.1-1
> ii  libstdc++6              8.3.0-6
>
> Versions of packages apt recommends:
> ii  ca-certificates  20200601~deb10u1
>
> Versions of packages apt suggests:
> pn  apt-doc                      <none>
> pn  aptitude | synaptic | wajig  <none>
> ii  dpkg-dev                     1.19.7
> ii  gnupg                        2.2.12-1+deb10u1
> ii  gnupg2                       2.2.12-1+deb10u1
> pn  powermgmt-base               <none>
>
> -- no debconf information

CC'd Julian, who is the author of the patch.