I've been trying to update my stuff on my machine, and it seems like it can't read my package list. It seems like every time i do the sudo apt-get install *something* && sudo apt-get update it gets stuck at reading package list, this have not been a problem before. Here is my specs and whatnot :

  • Memory : 15.8 gb
  • Processor : AMD Phenom(tm) II x4 965 Processor x 4
  • Graphics : Gallium 0.4 on AMD BARTS
  • OS type : 32-bit
  • Netspeed : enter image description here
  • 2
    Just clarifying... you are talking about executing sudo apt-get update, correct?
    – colboynik
    Feb 5, 2013 at 23:31
  • 2
    In Software Sources, see if selecting another server, instead of your current one, helps.
    – user25656
    Feb 6, 2013 at 2:24
  • Sorry for not writing more about this problem. But here's the deal! everytime i run a sudo apt-get update, sudo apt-get upgrade or 'sodu apt-get install something' it will get to it eventually, but it takes along 30 minutes ti read thru the list. Ive tried changing server, and that didnt help.
    – Dre
    Feb 6, 2013 at 16:20
  • What's the specifications of your computer and your internet connection? Edit your question with new information don't add it in the comments...
    – Alvar
    Feb 6, 2013 at 16:21
  • btw, why do you have 32-bit on that specification? It makes no sense. I can't figure out your problem though, how many different servers have you tried? This answer might help, askubuntu.com/a/44900/10698
    – Alvar
    Feb 6, 2013 at 16:53

4 Answers 4


I've seen that as well.

I don't have a solution, but I have a workaround (echo 3 | sudo tee /proc/sys/vm/drop_caches) and potentially more information so someone can bring the investigation any further.

It's not a network issue because at "Reading package list...", it is just reading files in /var/lib/apt/lists/. A:

strace -tt -T -fo strace.log apt-get update


16394 14:43:03.921130 open("/var/lib/apt/lists/gb.archive.ubuntu.com_ubuntu_dists_precise_main_binary-i386_Packages", O_RDONLY|O_LARGEFILE) = 7 <0.000012>
16394 14:43:03.995238 read(6, "-3.1ubuntu2)\nConflicts: linux86\n"..., 32444) = 32444 <0.000111>
16394 14:43:05.787187 read(6, "c (<< 1:14.b.4-dfsg), erlang-exa"..., 32239) = 32239 <0.000069>
16394 14:43:05.788025 read(6, ".deb\nSize: 42130\nMD5sum: c7de671"..., 31695) = 31695 <0.000068>
16394 14:43:05.870734 read(6, "5: 29c4b395a92bdc12932f151c3643a"..., 31607) = 31607 <0.000071>
16394 14:43:05.890862 read(6, "e-pack-af-base\nFilename: pool/ma"..., 32538) = 32538 <0.000070>
16394 14:43:05.891425 read(6, "buntu-usb-live, ubuntu-dvd-live,"..., 32090) = 32090 <0.000066>
16394 14:43:05.891960 read(6, "cd9755b03ac2c9b8251125c7b6618\nDe"..., 32195) = 32195 <0.000034>
16394 14:43:06.043001 read(6, "rg>\nArchitecture: all\nVersion: 2"..., 32535) = 32535 <0.000072>

See how those 8 read system calls took over 2 seconds even though each individual call takes less than 1 ms. Running time apt-get update or looking at top, that process is not busy between those two calls. So why the delay?

Then I did:

echo t > /proc/sysrq-trigger

a few times and looked at the outcome in kern.log:

 apt-get         D 00000000     0 16790  12706 0x00000000
  e8695d30 00000086 f7bd5e6c 00000000 f7bd5e44 f74a6580 c1990e00 c1990e00
  efe46efe 000042cb f7b9de00 e71a7230 f74a6580 c107e116 00000000 00000000
  044aa200 00000000 00000000 00000000 00000000 e8695d0c e8695d0c c1038de8
 Call Trace:
  [<c107e116>] ? enqueue_entity+0x186/0x220
  [<c1038de8>] ? default_spin_lock_flags+0x8/0x10
  [<c15e13bd>] ? _raw_spin_lock_irqsave+0x2d/0x40
  [<c15e0533>] schedule+0x23/0x60
  [<c15deecf>] schedule_timeout+0x12f/0x290
  [<c1075c38>] ? ttwu_do_activate.constprop.86+0x58/0x70
  [<c1055190>] ? usleep_range+0x40/0x40
  [<c15e0846>] io_schedule_timeout+0x86/0xd0
  [<c15cef7d>] balance_dirty_pages.isra.17+0x3f5/0x4b4
  [<c15e118d>] ? _raw_spin_lock+0xd/0x10
  [<c1180781>] ? __set_page_dirty_buffers+0x81/0xb0
  [<c110deb5>] ? set_page_dirty+0x55/0x60
  [<c11812c9>] ? __block_page_mkwrite+0xe9/0x170
  [<c110f3ae>] balance_dirty_pages_ratelimited_nr+0xde/0x100
  [<c1126f53>] do_wp_page+0x503/0x830
  [<c1128ef7>] handle_pte_fault+0x267/0x2c0
  [<c1129c62>] handle_mm_fault+0x1e2/0x280
  [<c15e4988>] do_page_fault+0x158/0x4c0
  [<c104e4dc>] ? irq_exit+0x5c/0xa0
  [<c15e22d0>] ? do_debug+0x180/0x180
  [<c15e4830>] ? vmalloc_fault+0x195/0x195
  [<c15e1c53>] error_code+0x67/0x6c

So, not sure what that means but that looks about the handling of page faults, so points at a potential memory management issue.

I then tried a:

echo 3 >/proc/sys/vm/drop_caches

And that did make the problem go away.

Now, it very much looks like a kernel issue. So, I've updated to the latest kernel (3.8 backport from raring) and that's where I'm at. Will update if the problem persists with the newer kernel.


The problem does persist with the new kernel, though not as bad. And same thing,

echo 3 | sudo tee /proc/sys/vm/drop_caches

clears the problem for a while. I've only seen that happen on MSI laptops (Product Name: CR61 2M/CX61 2OC/CX61 2OD).

Edit December 2015

As confirmed by btrace aptitude/apt-get does appear to do some disk I/O at the time. It's got a temporary file (/var/cache/apt/pkgcache.bin.<random-chars>) mmapped in memory which is why it doesn't show in the strace output.

Still can't explain why it only happens on some machines only, why dropping caches helps, why switching to 64bit helps.

If somebody can reproduce it, an interesting test could be to see if that also happens when running under eatmydata or if moving /var/cache/apt onto tmpfs or a ramdisk helps.

  • 1
    On 5th of April, 2014 I can confirm that the problem still exists. Tested on: Linux Mint 16, 32 bit, running on 64 bit processor, Lenovo W520, and: Kubuntu 12.10 32 bit, again running on 64 bit hardware, custom built desktop. (and the solution/workaround suggested here also works :) ) Apr 5, 2014 at 19:13
  • @fritzone, I remember seeing the problem reported elsewhere where people were saying that switching to a 64bit OS fixed the problem. Apr 5, 2014 at 20:01
  • I plan to switch back to a 64 bit OS too. Before, on the desktop I had a 64 bit version of 12.10 and had no problems like this. Apr 5, 2014 at 20:02
  • The problem still exists on ubuntu 14.04 :-(. Your solution with echo 3 to drop_caches worked. This has happened after some very buggy behavior of Inkscape with clipboard incorrectly clashing with Netbeans when it has opened 100 msgboxes or so... Even though Inkscape was killed, it left some mess in the system which totally slowed down apt-get reading the packages.
    – Palo
    Jan 3, 2015 at 0:46
  • I see it sometime too, and the workaround do not work for me. It is a 64 bit operating system here, on a samsung laptop with i7 and 8G ram. Only a reboot make the problem go away. Weird.
    – Rmano
    Feb 28, 2015 at 10:02

The advice at http://antti-juhani.kaijanaho.fi/newblog/archives/521 has sped it up for me several times on various computers:

sudo dpkg --clear-avail
sudo sync-available

(The blog also recommended sudo dpkg --forget-old-unavail between the 2 steps but apparently it's deprecated and no longer needed.)

  • Yes it worked amazing
    – Sayan Dey
    Mar 19, 2021 at 9:56

Follow the steps:

  • Clean out cache:

    sudo apt-get clean
  • Move the sources.list so apt cannot use it:

    mv /etc/apt/sources.list /etc/apt/sources.list1 && sudo apt-get update
  • Move it back then update:

    mv /etc/apt/sources.list1 /etc/apt/sources.list && sudo apt-get update 

Also check and remove any PPAs and source lines you don't need.


On my system, the cause was an incorrect value in the LANGUAGE= environment variable. It should hold values such as en:fr:de, and not en_US.UTF-8,sl_SI.UTF-8:

# locale

When ran (via strace), the apt-get update command clonks on the read() call. It takes ages to execute, and eats all the available cycles of one CPU core:

# strace apt-get update
read(5, "form, hardware::opengl, implemen"..., 32146) = 32146
read(5, " Maintainers <pkg-bluetooth-main"..., 32658) = 32658
read(5, ": 17569748\nMD5sum: 9c20d52f9a0d5"..., 32200) = 32200
brk(0x55ac79212000)                     = 0x55ac79212000
read(5, "scription-md5: ca1156b27bec24d4c"..., 32469) = 32469
read(5, " Boost.Math Library\nMulti-Arch: "..., 32477) = 32477
read(5, "epends: libc6 (>= 2.4), lsb-base"..., 32648) = 32648
^C--- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} ---
strace: Process 18452 detached

If I set LANGUAGE= to a correct value (such as en), everything goes back to normal again:

# export LANGUAGE=en

# locale

# apt-get update
Hit:1 http://ftp.at.debian.org/debian experimental InRelease
Ign:3 http://ftp.at.debian.org/debian jessie InRelease                                                      
Hit:4 http://ftp.at.debian.org/debian jessie-updates InRelease  
Hit:5 http://ftp.at.debian.org/debian jessie-backports InRelease                                                                             
Hit:6 http://ftp.at.debian.org/debian sid InRelease                                                                    
Hit:7 http://ftp.at.debian.org/debian stretch InRelease                               
Hit:8 http://ftp.at.debian.org/debian stretch-updates InRelease                                             
Hit:9 http://ftp.at.debian.org/debian jessie Release                                  
Hit:2 http://screenshots.getdeb.net xenial-getdeb InRelease                           
Hit:10 http://security.debian.org jessie/updates InRelease      
Hit:11 http://security.debian.org stretch/updates InRelease
Reading package lists... Done 
  • Oh, and of course I put the incorrect value there myself a few years ago. Funnily enough, apt was working flawlessly until yesterday, after II apt-get upgrade'd the system (Debian sid).
    – shkitch
    Dec 5, 2016 at 9:40
  • I've suddenly encountered this on a 32-bit install of Debian Jessie that's been working for years (decades?). Nothing's change in the machine configuration, but it suddenly started happening. I don't have LANGUAGE= set to anything, though. Setting it to "en" or using C for all LC_* locale variables didn't help yet. Dec 12, 2016 at 21:19

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