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I've done something (I can't remember what) and now when I log in, just after entering my details, I see the background with my mouse cursor and nothing happening. Then, after about 20 seconds (presumably a timeout) the hard drive keeps loading and I get my desktop.

I tried install bootchart2:

apt-get install bootchart2 pybootchartgui

I followed their instructions here and added the following line to /etc/default/grub:

initcall_debug printk.time=y quiet init=/sbin/bootchartd ...

when I run update-grub I get the following error message:

/usr/sbin/grub-mkconfig: 12: /etc/default/grub: initcall_debug: not found

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You can also use strace to connect to various processes during login to see what's the hang up: cyberciti.biz/tips/linux-strace-command-examples.html –  slm Apr 19 at 21:34
@slm I wouldn't know where to start with strace. How do I find out what's happening at login? What do I run it against? –  Jason Apr 19 at 21:40
@slm I should add that the computer doesn't actually freeze (I can still move the mouse around), there's just no icons and no hard drive activity. –  Jason Apr 19 at 21:52
Right I know it wasn't freezing, but these methods were still appropriate. –  slm Apr 19 at 21:54
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1 Answer 1

up vote 4 down vote accepted

This type of issue can be tricky to debug. For starters it's helpful to isolate it to either a network or HDD access issue.

This is done by eliminating potential causes until you're left with the culprit.


Before we get started we'll be making use of several applications that you may need to install. I'm not going to detail how to do this, I'm assuming you know how to install applications and will do so when required to perform a particular step.

Also we'll be making use of the system's console. To access it do the following: Ctrl + Alt + F2. You can use a similar keyboard combo to switch back to your primary display where your graphical desktop is. That would be this key combo: Ctrl + Alt + F1.


Using the app nethogs is a good place to start. I like to use it since it will show you the applications that are trying to access the network. Perhaps one of these applications is causing the hanging.

Before we can use nethogs we need to determine which network interface is being used by our system. Here are the ones I have on my laptop:

$ ip -o link show | cut -d" " -f2

I know from experience that my wireless is wplp3s0. The ethernet is em1. Let's start with WiFi.

$ sudo nethogs wlp3s0

Resulting in this type of output:

NetHogs version 0.8.0

  PID USER     PROGRAM                      DEV        SENT      RECEIVED       
979   saml     ../bin/google-chrome-stable  wlp3s0     1.943       2.547 KB/sec
2376  saml     /usr/bin/pidgin              wlp3s0     0.000       0.000 KB/sec
21789 saml     ssh                          wlp3s0     0.000       0.000 KB/sec
9618  saml     ssh                          wlp3s0     0.000       0.000 KB/sec
10267 saml     ssh                          wlp3s0     0.000       0.000 KB/sec
?     root     unknown TCP                             0.000       0.000 KB/sec

  TOTAL                                                1.943       2.547 KB/sec 

Once we've isolated the issue to a few PIDs that appear to be lopsided in having a lot of SENT data without any receiving data, we'll need to dive in deeper and use strace to try and see what aspect of this network access is getting hung up. To accomplish this you can use strace like so:

$ strace -s 2000 -o somepid.log -p <PID>

Where <PID> is one of the process IDs identified from nethogs.

Disk I/O

If we've determined that the issue isn't with our network, the next place to explore would be looking to see if a process is having issues accessing the HDD and getting blocked in some fashion.

This can be trickier to debug but you'll likely make use of tools such as lsof, strace, and fatrace to further refine your search.

Anything else?

One place where you can fairly quickly determine if something is suspect is to disable any applications from starting up when you log in. To do this under GNOME you can launch this dialog: gnome-session-properties.

                    ss of dialog

Within this dialog I'd attempt to disable everything or applications you think are suspect and start doing reboots to see if the issue goes away.

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Ok, when I run that first command I get lo, eth0, and wlan0. nethogs lo produces only a single entry: PID ?, USER root, PROGRAM unknown TCP, SENT 0.000, RECEIVED 0.000. running nethogs eth0 results in a large list (this time I didn't disabled the ethernet adaptor). Most of them have no PID and USER as root, then a bunch of numbers under PROGRAM. One has a PID of 5215 with USER as armanschwarz (my username). The program for this one is ..m --password-store=detect (presumably this is just a partial?) –  Jason Apr 19 at 22:44
@ArmanSchwarz - wlan0 is your wifi. Yes the output is partial. –  slm Apr 19 at 22:45
@ArmanSchwarz - yes it's showing things as they come and go. We're looking for things that stay on the list and don't go away. Culprits also have a lot of send w/ no receiving. These would be programs that are trying to get a resource that isn't acknowledging them. –  slm Apr 19 at 22:47
@ArmanSchwarz - I've added some additional updates, let me know if that helps. –  slm Apr 20 at 0:31
Thanks, slm and @ArmanSchwarz. You guys just helped me keep my laptop wifi from hanging on a remembered old network at boot. –  mikeserv Apr 20 at 2:02
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