Re: [Xen-devel] xend leaks/bugs/etc

[Jacob Gorm Hansen <jacobg@xxxxxxx>]

Ian Pratt wrote:

> > > I think the goal should be to have the least amount of code 
> > > (regardless of language) in whatever is running as a daemon.
> > Exactly - the least amount of code that meets functional 
> > requirements. 
>
> It's hard to beat python for this sort of thing...
Not if you factor in the footprint of the python compiler and runtime 
and its large set of standard modules, and its unpredictable runtime 
performance (memory leaks and lack of static checking). It seems to me 
the 'python for xend' experiment has failed, and that this is further 
evidenced by that fact that a) Anthony/IBM has decided to write a 
competing implementation from scratch b) Xend developers blame Twisted, 
and now c) Twisted developers blame Xend. Short of name-calling, I do 
not see how we can proceed from here.
No other serious OS has vital components written in interpreted 
dynamically typed languages, I do not see why Xen needs to be the only 
one. Perhaps it is true that development is a little faster in Python (I 
have extensive Python experience, yet I have felt much more comfortable 
reading and modifying code in the C-implemented parts of the system than 
in Xend which remains a complete blackbox to me), but still we are 
making users pay for our (perceived) increased productivity with their 
memory, their system stability, and their runtime performance. I am not 
an engineer, but to me this seems like poor engineering.
The Intermezzo project tried something similar some years back, having a 
kernel component in C and a user-level file server in Perl. While there 
was great progress in the beginning, the project more or less died when 
the limitations of Perl were reached. A rewrite in C was attempted, but 
at that point the project had run out of steam.
Jacob

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