Sparrow is a high throughput, low latency distributed cluster scheduler. Sparrow is designed for applications that require frequent research allocations due to launching very short jobs (e.g., jobs composed of 100ms tasks). To ensure that scheduling does not become a bottleneck, Sparrow distributes scheduling over several loosely coordianted machines. Each scheduler uses a constant-time scheduling algorithm based on on-demand feedback acquired by probing slave machines. Sparrow can perform task scheduling in milliseconds, two orders of magnitude faster than existing approaches.