  Long tail latency of short flows (or messages) greatly affects user-facing
applications in datacenters. Prior solutions to the problem introduce
significant implementation complexities, such as global state monitoring,
complex network control, or non-trivial switch modifications. While promising
superior performance, they are hard to implement in practice. This paper
presents CloudBurst, a simple, effective yet readily deployable solution
achieving similar or even better results without introducing the above
complexities. At its core, CloudBurst explores forward error correction (FEC)
over multipath - it proactively spreads FEC-coded packets generated from
messages over multipath in parallel, and recovers them with the first few
arriving ones. As a result, CloudBurst is able to obliviously exploit
underutilized paths, thus achieving low tail latency. We have implemented
CloudBurst as a user-space library, and deployed it on a testbed with commodity
switches. Our testbed and simulation experiments show the superior performance
of CloudBurst. For example, CloudBurst achieves 63.69% and 60.06% reduction in
99th percentile message/flow completion time (FCT) compared to DCTCP and PIAS,
respectively.
