Re: [tlug] How can my computer forget to do stuff sometimes?

[Darren Cook <darren@example.com>]

> I run Ubuntu Lucid, with the Gnome desktop, in combination with Compiz 
> and Emerald. ...
> 80 to 90 percent of the time, ... everything is great.
> 
> But now and again, I boot the computer, and something will be off. For 
> instance, the Emerald window manager won't be on, so my windows won't 
> have any frames on them. Or sometimes recenly the little icon for 
> rebooting and restarting the computer is missing from my Gnome panel.

If the component not starting is officially supported by Ubuntu then you
should file a bug report. They might pour scorn on it, as all you can
tell them is it happens on 10-20% of boots. But if enough people report
the bug eventually the programmers realize they need to make it more
tolerant of different boot timings.

Trawling your boot log files first to try and find an error message from
Emerald or whatever would be a good idea.

> from boot to boot. As far as I understand it, when the computer boots, 
> it runs through the same list of tasks to start things up, in the same 
> order every single time.

The boot sequence starts things in a fixed order, starting each thing
running in the background before going to the next. If one step involves
another machine over the network (connecting a samba drive, connecting
to an NTP server, doing a DNS lookup, etc.) then it can easily finish in
0.5 second, or finish in 10 seconds; maybe a median of 7 seconds.

Imagine this scenario:
  "A" starts running in background;
  "B" connects to a samba drive, taking 7 seconds;
  "C" starts relying on A to do work properly. It is fine.

Now this one:
  "A" starts running in background;
  "B" connects to a samba drive, taking 0.5 seconds;
  "C" starts, but A is still initializing and hasn't started accepting
connections yet. So C fails to start.

You can view the bug as either A should fully initialize before moving
to the background (*), or that C should sit around waiting longer for A
to be ready before giving up. That is a decision that needs to be made
by the distro developer; next time you meet one shake them by the hand
and thank them heartily for managing to get anything to work at all!

Darren

*: See also distro wars, and quick boot-ups being a key feature.



-- 
Darren Cook, Software Researcher/Developer

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