Technology Brief for Apple's Grand Central Multicore Paradigm [pdf]

http://images.apple.com/macosx/technology/docs/GrandCentral_TB_brief_20090608.pdf

by nickb • 17 years ago

42 12 17 years ago

images.apple.com

swannodette2• 17 years ago

While all the Apple hardware announcements look great, I think this is possibly an even more significant announcement. C/Objective-C/C++ gets lambdas and closures! It looks like Apple has a very interesting single machine concurrency story here.

Right now I'm really enjoying Clojure- it's lockless approach to single machine concurrency is plenty, plenty fun. Unfortunately the downside of learning Clojure is that many other popular languages look downright archaic to me in this regard now. Now reading over this document, whodathunk, concurrency programming might be as fun in C as it is in Clojure!

Gary_W_Longsine3• 17 years ago

Related to this is another key performance technology in Snow Leopard, OpenCL: http://images.apple.com/macosx/technology/docs/OpenCL_TB_bri... .

jmtulloss• 17 years ago

First of all, this is awesome.

I am missing some details though. Are these true closures? What are the scoping rules? Can you read data declared outside of your block? Can you alter it? Is the only way to keep alterations safe to use a private queue? I guess time (or a closer reading) will tell.

swannodette2• 17 years ago

More information about the implementation of blocks here: http://lists.cs.uiuc.edu/pipermail/cfe-dev/2008-August/00267...

gchpaco• 17 years ago

This encourages a very different style of multicore programming than is common on desktops today, closer to that of grid systems. Very interesting to see how this develops.

Gary_W_Longsine3• 17 years ago

Apple may have been inspired in part by their experience with XGrid [http://www.apple.com/server/macosx/technology/xgrid.html], based on the NeXTSTEP application Zilla [http://www.omnigroup.com/mailman/archive/macosx-talk/2000-Se...], and perhaps by PDO (Portable Distributed Objects) [http://en.wikipedia.org/wiki/NeXTSTEP]. I mention these somewhat obscure influences in response to your grid observation. Obviously there are several other (probably more immediate) influences on GCD and OpenCL as well (LLVM, OpenGL, various academic research on parallelized programming, etc.)

agocke2• 17 years ago

I wonder how this will affect the legacy methods of concurrency in OS X -- specifically POSIX threads. I know I wrote a number of C apps using POSIX threads that worked well in OS X and in Linux. While this is nice and interesting for Mac only programs, I hope that I don't have to rewrite my cross platform apps to take advantage of the API.

wmf• 17 years ago

Obviously pthread support won't be removed; pthread programs just won't play as nice with each other as Grand Central programs.

agocke2• 17 years ago

Well I didn't really mean to suggest that it would be removed, mainly about what kind of performance hit I would take by using pthreads instead of Grand Central. In addition, how well will pthread programs and GC programs work together. Normally, the threading is handled by the scheduler in a straightforward model, but if the GC model modifies the scheduler model, I'm not really sure what the results will be.

miratom• 17 years ago

A Job Queue is a great thing to have, especially when it provided for you, but it's hardly "revolutionary."

perneto• 17 years ago

This sounds inspired by SEDA (Staged Event-Driven Architecture). http://www.eecs.harvard.edu/~mdw/proj/seda/ It was about time someone made good use of it, too!

Is there more info available? The white paper is nice, but not too packed with detail.

Technology Brief for Apple's Grand Central Multicore Paradigm [pdf]

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