Re: upstart: please update to latest upstream version
On Fri, Feb 24, 2012 at 01:47:59AM -0800, Steve Langasek wrote:
> > I have. Not on debian, but on debianish system with dash. And the result
> > was that shellscripts are indeed the bottleneck. We still did convert to
> > upstart since we believed it would allow us to cut down the amount of
> > shell scripts. The event based architecture however forced much more
> > shell scripting that made the boot time improvement much less than
> > hoped.
> Interesting to know, thanks. Was this done in a head-to-head comparison
> with the systemd "no shell" boot?
Systemd was not at ready that time.. Every exec has a price, and if a upstart
stanza has a pre-start and post-start script, that is already two shell execs.
Any command in shell script that is not a shell builtin is more execs. In this
sense dash is worse, as it has less builtins that bash. for example sleep is
not a builtin...
The other factor of shell scripts is psychological. Since shell scripts are
so easy to modify, people tend to litter them with unneccesary checks,
settings, workarounds and other spagethi.
> >  stuff like this:
> > -snip-
> > post-start script
> > # wait until daemon is ready
> > timeout=6
> > while [ ! -e /var/run/cups/cups.sock ]; do
> > sleep 0.5
> > timeout=$((timeout-1))
> > -snip-
> Oh dear, you've managed to find the worst upstart job in Ubuntu ;)
> If you have other stuff *like* this, I'd be interested to see it. That
> particular upstart job is needed only because of peculiarities of how cups
> starts up.
Well that was a common development idiom with upstart when our developers
realized that neither "on started" or "on starting" did what they wanted...
Some of them were got rid of by changing upstream code to emit a signal when
I just grepped an Ubuntu system to see if there were similar cases in Ubuntu as well ;)