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What should I do when Ubuntu freezes?

My OS is Ubuntu 12.04. Sometimes the screen suddenly becomes frozen, except that the mouse can move around. I have no choice but to hit the power button of my laptop.

In Windows, whenever screen becomes frozen, I just hit Ctrl+Alt+Delete to invoke task manager, which is still responsive, and kill the processes that consumes most resources and are likely the culprit of the freezing.

But in Ubuntu, I don't know what some good way to deal with such a situation.

Thanks!

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marked as duplicate by Eliah Kagan, hbdgaf, jokerdino, fossfreedom Jun 15 '12 at 9:21

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

3 Answers

Try to switch to a different workspace Ctrl+Alt+one of you arrow keys, unless your system is completely frozen it should be able to switch workspaces

In the new workspace look for System Monitor in the dash, it is like Windows Taskmanager.

you should then be able to "kill" the process by right clicking on it.

If this doesn't work you can restart your desktop without having to do a hard shut-down by logging into one of your virtual desktops (Ctrl+Atl +F2(or 3-6)) then enter the following commands

sudo stop lightdm

you will get a notification: lightdm stop/wait then enter the following

sudo start lightdm

this will restart your Xserver and send you back to the login screen on your desktop or straight to your desktop if you log in automatically.

Note; this is still a semi-nuclear option, it will kill any programs that are running and you will lose any unsaved work but it is safer for your computer than holding the power button.

There is also a text based task manager called "top" that you can access from a terminal or your virtual desktops but it's directions are rather long, you can get information on how it works by entering this into a terminal

man top

and the command to launch the actual "text task manager" is:

top
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Thanks! I did switch to another tty by Ctrl-Alt-F2, and top to kill the most CPU and memory consumed processes, usually Firefox. Then I switched back by Ctrl-Alt-F7, but the screen was still frozen. So what else might possibly the reason of the problem? –  Tim Jun 15 '12 at 9:54
    
Since having had the misfortune of giving up Lucid and Maverick for Precise, before which I NEVER had this trouble and now have it all the time, this is hands-down the best work-around I've tried. Thank you very much! –  Russ Bateman Apr 16 '13 at 13:43
    
Thanks a lot.... –  kernel_panic Nov 18 '13 at 16:27
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You can switch to another tty by pressing Ctrl-Alt-F2, then type command top to find out which process used too much your CPU or Memory or I/O, then kill it if you want your system be responsing. (You need to consider whether it is safe to cancel a process, usually it's fine. like a browser firefox)

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Thanks! I did switch to another tty by Ctrl-Alt-F2, and top to kill the most CPU and memory consumed processes, usually Firefox. Then I switched back by Ctrl-Alt-F7, but the screen was still frozen. So what else might possibly the reason of the problem? –  Tim Jun 15 '12 at 9:54
    
1. After the kill. make sure you do not have other process that use too much your system resource. 2. if this problem happens after some behavior you do, can you say what you did before the frozen ? maybe it is a bug. –  NagatoPain Jun 15 '12 at 12:02
    
about 2, browsing internet in firefox, edit text files in gedit, viewing pdf filesin evince, viewing djvu files in djview4, and openning directories in nautilus. –  Tim Jun 15 '12 at 12:16
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There's a safe way to reboot a frozen Ubuntu:

  • Hold down Alt+Sys Rq(PrtScn key)key combination. There will be no visible output,while hold down the key combination,
  • press these keys in the order,one by one

    R E I S U B

    Spells “busier” backwards,and the system will be reboot after B is typed in the safe way.

  • links here

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    Tim and I have had a discussion, moved to chat here, that people may find helpful. It concerns the Ctrl+Alt+F1, Ctrl+Alt+Del alternative to Alt+SysRq+REISUB (to reboot more gently when the problem is less severe), and other matters relating to the details of what occurs when various methods are used to shut down or reboot an Ubuntu system. –  Eliah Kagan Jul 8 '12 at 15:07
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