I've been getting very excited about Node.js recently:
http://simonwillison.net/2009/Nov/23/node/
It's basically Twisted / Tornado but in JavaScript, and with the huge
advantage that, because it's brand new, it doesn't have any legacy
blocking APIs. Database access looks like this:
c.query("select * from articles").addCallback(function(rows) {
pretty_print(rows);
});
Even filesystem access is non-blocking:
posix.cat("/etc/passwd").addCallback(function(content) {
puts(content);
});
This made me think about non-blocking IO and Django. Theoretically,
many of the services that Django provides could be used in a non-
blocking environment such as that provided by Twisted or Tornado:
* URL routing shouldn't need to be blocking - it's just dispatching to
a function based on a regex (though this is stymied by thread locals)
* Form handling shouldn't need to block on I/O
* If we cache templates in memory instead of reading from disk each
time, rendering them shouldn't need to block on IO either
* SQL statement generation with the ORM shouldn't need to block either
That last one is particularly interesting to me. My understanding is
that much of the ORM refactoring for multi-db consisted of improving
the separation of SQL generation from actual database interaction.
Being able to do something like this would still be incredibly useful:
def my_async_view(request, response):
query = Blog.objects.filter(pubdate__year = 2009).exclude
(tag__slug = 'sport')
def done(rows):
response.render('blog.html', {'rows': rows})
db.execute_async(query, done)
The db.execute_async method would take a queryset and a callback,
execute the query asynchronously and pass the result to that callback.
I've invented an imaginary potential async replacement for the
blocking response=view(request) idiom.
I don't think async support should be baked in to Django core, but
it's a very interesting thing to think about. Should we eventually
break Django up in to smaller reusable libraries this kind of thing
would be an exciting use case.
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