Folly

Facebook’s library of high-performance C++ components designed to scale across massive distributed systems.

Folly provides a collection of C++17 reusable components used internally at Meta to handle extreme performance requirements. It excels where the standard library falls short, offering optimized tools like AtomicHashMap, the asynchronous Futures framework, and the high-speed FBString implementation. By prioritizing cache efficiency and reduced lock contention, Folly enables engineers to write low-latency code that manages thousands of concurrent connections (via Proxygen) or heavy data processing loads with minimal overhead.

https://github.com/facebook/folly