D-Programming-Language/phobos — pull request #2645 by complexmath (2014-10-27 23:39:58+00:00)
Title: Add message free list to std.concurrency

I experimented with a lock-free freelist (which turned out to be ridiculously slow) and a locked freelist. The locked freelist provided a bit of a performance advantage over no free list at all in my tests, and should scale better in large applications.