Unicorn future plans

Eric Wong normalperson at yhbt.net
Mon Jun 14 18:10:36 EDT 2010

John-Paul Bader <hukl at berlin.ccc.de> wrote:
> Hey, 
> your plans sound great except for ignoring FreeBSD ;)
> Seriously many many Servers, including many which I administrate run
> on FreeBSD and they do so very well. I'm not very familiar with the
> internals of the FreeBSD Kernel but I can assure you that it runs
> perfectly on 8 and 16 core machines and I would extremely happy if I
> could continue to use unicorn on them.

Hi John-Paul,

Reread my post carefully, not much is changing for 8-16 core users.
FreeBSD and SMP will continue to be supported.  I wasn't referring
to SMP at all when I was talking about Linux-only bits.

> It should be easier to maintain a FreeBSD version as they (FreeBSD
> developers) tend to aim for more consistency across releases than
> Linux. You said once that you don't run any BSD machines but I'd be
> happy to offer you access to one of my BSD servers for testing.

Thanks for the offer.  I'll keep it in mind if I need it again.

> Furthermore since Mac OS X and FreeBSD share many features like kqueue
> and many Ruby developers are running macs it would make even more
> sense to at least care about BSD even if its not you primary platform. 

I know, I've fixed some things on OSX platforms via FreeBSD (OSX scares
me with its GUI-ness).  Keep in mind kqueue (and epoll) are worthless
for Unicorn itself since Unicorn only handles one client at a time.

However, Rainbows! can already use kqueue/epoll with EventMachine and

> I don't want to start a flame war or say that one OS is better than
> another. Linux is certainly great but so is FreeBSD. For the SMP part
> I recommend the following page on freebsd.org:

Again, I wasn't talking about SMP at all.   SMP works fine on current
Unicorn and mid-sized servers.  When going to more cores, SMP itself
is a bottleneck, not the kernel.

With Unicorn 2.x, I'm targeting NUMA hardware that isn't available in
commodity servers yet.  Currently, NUMA makes _zero_ sense in web
application servers, but in case things change in a few years, we'll be

It may be a chicken-and-egg problem, too.  Hardware manufacturers are
slow to commoditize NUMA because a good chunk of software can't even
utilize SMP effectively :)

> To conclude I can only say that I'm running unicorn on several FreeBSD
> hosts and so far I couldn't be happier with it. As stated before, I'd
> be more than happy to continue using that setup.

Again, don't worry :)  You'll be able to continue using everything

> Kindest regards and thanks for all you efforts,

No problem.  Please don't top post in the future.

Eric Wong

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