Nu: Achieving Microsecond-Scale Resource Fungibility with Logical Processes

We propose logical processes, a new abstraction that splits the classic UNIX process into units of state called proclets. Proclets can be migrated quickly within data center racks, to provide fungibility and adapt to the memory and compute resource needs of the moment. We prototype logical processes in Nu, and use it to build three different applications: a social network application, a MapReduce system, and a scalable key-value store. We evaluate Nu with 32 servers. Our evaluation shows that Nu achieves high efficiency and fungibility: it migrates proclets in ≈100µs; under intense resource pressure, migration causes small disruptions to tail latency-the 99.9 th percentile remains below or around 1ms-for a duration of 0.54-2.1s, or a modest disruption to throughput (<6%) for a duration of 24-37ms, depending on the application.