I wrote at a number of occasions (here or here), that it could be really beneficial to use a different memory allocator for highly-threaded workloads, as the standard allocator is well ... the standard, however not very effective as soon as many threads comes into play.

I didn't wrote about this as it was in my phase of silence but there was some change in the allocator area, Solaris 10 got a revamped mtmalloc allocator in version Solaris 10 08/11 (as described in "libmtmalloc Improvements"). The new memory allocator was introduced to Solaris development by the PSARC case 2010/212.

But what's the effect of this new allocator and how does it works? Rickey C. Weisner wrote a nice article with "How Memory Allocation Affects Performance in Multithreaded Programs" explaining the inner mechanism of various allocators but he also publishes test results comparing Hoard, mtmalloc, umem, new mtmalloc and the libc malloc. Really interesting read and a must for people running applications on servers with a high number of threads.