Re: [Haskell-cafe] [ANN](and feedback request) unagi-chan: Fast and scalable concurrent queues for x86, with a Chan-like API

On Tue, Jul 15, 2014 at 2:44 AM, Gregory Collins wrote:

On Thu, Jul 10, 2014 at 8:39 PM, Brandon Simmons wrote:

...

I'm happy to finally release unagi-chan, an implementation of high-performance concurrent FIFO queues that have an API very similar to Control.Concurrent.Chan. You can see benchmarks and documentation here:

It's difficult to overstate how much faster unagi-chan is than Control.Concurrent under contention, I'm seeing >10x improvements in the 100 readers/100 writers benchmark on this quad-core machine. I'll have to try it on the 8-core at work. Performance seems to be predictably fast as you scale the number of workers, unlike the others which asymptotically explode during contention. Really impressive work, Brandon.

Thanks a lot. And thank you for trying it out.

How close is unagi-chan to being a drop-in replacement for MVar? Since this implementation seems to clearly be better, personally I would wonder if it shouldn't just replace the existing one in the standard library.

It's a drop-in replacement for all non-deprecated functions, except for the splitting of input and output ends of the chan and the handling of async exceptions in the reader. I wouldn't be comfortable advocating for it as a replacement, personally. Mostly because of a few questions and misgivings I have about some implementation details (especially related to memory model stuff). They're all documented in the source and I'm very comfortable with people using it in production, but only after running the test suite.

Also: can you use the same technique to get a fast implementation of bounded queues?

There's a pretty straightforward path to at least some sort of "fuzzy" bounded queue that just fails (rather than the writer block), which might end up as simply a `chanSize :: InChan a -> IO Int`. Please feel free to add to the discussion here: https://github.com/jberryman/unagi-chan/issues/1 Thanks again, Brandon

G -- Gregory Collins