Rain drops

raindrops is a real-time stats toolkit to show statistics. It is designed for preforming servers such as unicorn, but should support any Rack HTTP server on platforms supporting POSIX shared memory. It may also be used as a generic scoreboard for sharing atomic counters across multiple processes.
Features
• counters are shared across all forked children and lock-free
• counters are kept on separate cache lines to reduce contention under SMP
• may expose server statistics as a Rack Middleware endpoint (default: raindrops)
• middleware displays the number of actively processing and writing clients from a single request regardless of which worker process it hits.