Despite decades of innovation, existing hash tables fail to achieve peak performance on modern hardware. Built around a relatively simple computation, i.e., a hash function, which in most cases takes only a handful of CPU cycles, hash tables should only be limited by the throughput of the memory subsystem. Unfortunately, due to the inherently random memory access pattern and the contention across multiple threads, existing hash tables spend most of their time waiting for the memory subsystem to serve cache misses and coherence requests.

In contrast to hardware-based isolation solutions, language-based systems support crossing of isolation boundaries with an overhead of a function call. Moreover, the strong type system of a safe language provides support for secure communication in the face of complex, semantically-rich interfaces, i.e., support for fault isolation and end-to-end zero-copy communication through isolation of object spaces and controlled ownership on the shared exchange heap. If historically, safety was prohibitive due to overheads of a managed runtime, today, languages like Rust achieve the performance of unsafe C hence empowering language-based systems to support practical isolation with fine-grained boundaries and frequent communication.

Rust is the first practical programming language that has the potential to provide fine-grained isolation of untrusted computations at the language level. A combination of zero-overhead safety, i.e., safety without a managed runtime and garbage collection, and a unique ownership discipline enable isolation in systems with tight performance budgets, e.g., databases, network processing frameworks, browsers, and even operating system kernels.