On 12/08/2012 01:40 AM, Darren New wrote:
> http://www.infoq.com/news/2012/08/azul-zing-free
>
> I am pretty sure this means it's real-time GC.

Oh thank God. They've had this magical silver bullet all along, and now 
they've /finally/ released it to the rest of the world. How did we ever 
manage without it? :-P

I like how the algorithm description is sufficiently vague that you 
can't tell how it actually works. It claims to be able to mark 
concurrently "without live objects escaping the collector's reach", but 
doesn't explain how. It says it can delete a page after all objects have 
been relocated, and it "detects" any attempt to access a moved object, 
but again doesn't say how. (It sure /sounds/ like they're saying they do 
some O(n) operation on every single pointer read, which is of course 
absurd.) Come to think of it, they say they use page features to 
implement some of this stuff - which is interesting, since only the OS 
can do that...

Also,

   "Initial in-memory tests on the full Wikipedia English-language site 
index show Zing is truly pauseless while managing a heap in excess of 
140 GB."

Since it's impossible to have a machine with 140GB of RAM, what's the 
point of having a heap that large? It'll just spend forever swapping. 
Surely you'd get far better performance by implementing some explicit 
file handling yourself?

Post a reply to this message