Package: apt
Version: 1.0.9.3
Severity: normal
Dear Maintainer,
running apt-cache or apt-search as a non-root user is (was) very slow on
my machine:
$ time apt-cache show gmpc
...
apt-cache show gmpc 4.95s user 0.59s system 83% cpu 6.601 total
$ time sudo apt-cache show gmpc
...
apt-cache show gmpc 0.06s user 0.04s system 62% cpu 0.172 total
I tracked down the problem using strace and it seems that if a APT .list
file is not readable by a non-root user, apt-cache (in this case) goes
much, much slower:
$ time apt-cache show gmpc
...
apt-cache show gmpc 0.06s user 0.05s system 74% cpu 0.139 total
$ sudo touch /etc/apt/sources.list.d/foo.list
$ sudo chmod 600 /etc/apt/sources.list.d/foo.list
$ time apt-cache show gmpc
E: Opening /etc/apt/sources.list.d/foo.list - ifstream::ifstream (13:
Permission denied)
E: The list of sources could not be read.
E: The package lists or status file could not be parsed or opened.
E: No packages found
apt-cache show gmpc 0.05s user 0.04s system 73% cpu 0.120 total
$ sudo apt-get update
...
$ time apt-cache show gmpc
...
apt-cache show gmpc 4.95s user 0.59s system 83% cpu 6.601 total
$ sudo chmod 644 /etc/apt/sources.list.d/foo.list
$ time apt-cache show gmpc
...
apt-cache show gmpc 0.06s user 0.04s system 62% cpu 0.172 total
strace shows that, when it's fast, apt-cache open the Packages file in
/var/lib/apt/lists/ and jumps directly using fseek() to the right
position to read the information about the package.
But when it's slow, it does the following:
* it opens the same Package file
* it reads the whole file, 32kB per 32kB
* it opens a temporary file in /tmp
* it opens the related _InRelease file
* it writes into the temporary file... stuff (checksums it seems, from
the _InRelease file I guess?)
* after reading the while _InRelease file, it closes it, seek to the
beginning of the temporary file and reads everything, then closes it.
* then, it starts again with the next Package file
So, yeah, it's much slower in the end.
Jonathan
-- Package-specific info:
-- (no /etc/apt/preferences present) --
-- (/etc/apt/sources.list present, but not submitted) --
-- System Information:
Debian Release: jessie/sid
APT prefers unstable
APT policy: (500, 'unstable'), (101, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 3.16.0-4-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Versions of packages apt depends on:
ii debian-archive-keyring 2014.1
ii gnupg 1.4.18-4
ii libapt-pkg4.12 1.0.9.3
ii libc6 2.19-13
ii libgcc1 1:4.9.2-1
ii libstdc++6 4.9.2-1
apt recommends no packages.
Versions of packages apt suggests:
pn apt-doc <none>
ii aptitude 0.6.11-1+b1
ii dpkg-dev 1.17.21
ii python-apt 0.9.3.11
ii synaptic 0.81.2
-- debconf-show failed
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