Oops is a caching web proxy that uses one thread (lightweight process) for every connection. This technique does cost additional memory, but allows good concurrency of requests while avoiding the need for complex non-blocking programming. Oops was apparently designed as a wide-scale shared proxy.
Although Oops' programming model makes it easy to implement persistent connections, Oops insists on opening a separate connection to the server for every single resource fetch, which disqualifies it from production usage.