Thread safety issue (I think) with defaultdict

[Chris Angelico]

On Sat, Nov 4, 2017 at 2:45 AM, Steve D'Aprano
<steve+python at pearwood.info> wrote:
> So, all else being equal, which is likely to have more bugs?
>
>
> 1. Multiprocessing code with very little coupling between processes; or
>
> 2. Threaded code with shared data and hence higher coupling between threads?
>

Obviously, option 1. But that's "all else being equal". How often can
you actually have your processes that decoupled? And if you can write
your code to be completely (or largely) decoupled, what's to stop you
having your *threads* equally decoupled? You're assuming that "running
in the same memoryspace" equates to "higher coupling", which is no
more proven than any other assertion. Ultimately, real-world code IS
going to have some measure of coupling (you could concoct a scenario
in which requests are handled 100% independent of each other, but even
with a web application, there's going to be SOME connection between
different requests), so all you do is move it around (eg in a web app
scenario, the most common solution is to do all coupling through a
database or equivalent).

ChrisA