Hoard

The Hoard memory allocator is a very fast, memory-efficient and scalable memory allocator
The Hoard memory allocator is a very fast, memory-efficient and scalable memory allocator. Hoard runs on a variety of platforms, including Linux, Solaris, and Windows.

Hoard is a drop-in replacement for malloc() that can dramatically improve application performance, especially for multithreaded programs running on multiprocessors. No change to your source is necessary. Just link it in or set just one environment variable.

Multithreaded programs often do not scale because the heap is a bottleneck. When multiple threads simultaneously allocate or deallocate memory from the allocator, the allocator will serialize them.

Programs making intensive use of the allocator actually slow down as the number of processors increases. Your program may be allocation-intensive without you realizing it, for instance, if your program makes many calls to the C++ Standard Template Library (STL).

False Sharing
The allocator can cause other problems for multithreaded code. It can lead to false sharing in your application: threads on different CPUs can end up with memory in the same cache line, or chunk of memory. Accessing these falsely-shared cache lines is hundreds of times slower than accessing unshared cache lines.

Blowup
Multithreaded programs can also lead the allocator to blowup memory consumption. This effect can multiply the amount of memory needed to run your application by the number of CPUs on your machine: four CPUs could mean that you need four times as much memory. Hoard is a fast allocator that solves all of these problems.