An Empirical Study of Flash Crowd Dynamics in a P2P-Based Live Video Streaming System

Peer-to-peer (P2P) based live video streaming system has emerged as a promising solution for the Internet video streaming applications, partly evident from commercial deployment of several large-scale P2P streaming systems. The key is to leverage the resources available at end users, which offers great potential to scale in the Internet. Flash crowd poses a unique challenge for live streaming systems, in which there could be potentially hundred of thousands of users joining the system during the initial few minutes of a live program. This adds considerable difficulty in particular for a P2P based system in quickly ramping to a scale that can provide reasonable streaming services for newly incoming peers. In this paper, we examine the system dynamics under flash crowd based on measurements obtained from the Coolstreaming system. We are particularly concerned with the impact and user behaviors during flash crowd. The results reveal a number of interesting observations: (1) the system can scale up to a limit during the flash crowd; (2) there is a strong correlation between the number of short sessions and joining rate due to the resource competition among newly joined peers; (3) the user behavior during flash crowd can be best captured by the number of retries and the impatience time.