The goal of this paper is to minimize service disruption, a unique phenomenon in peer-to-peer (P2P) streaming system and the major contributing factor to degrade user experience. In order to improve its streaming quality and stability, a P2P system should select peers with abundant bandwidth resource and prospect longevity as the parents of other peers. Towards this end, we propose PRW (peer resilient weight), a metric to evaluate a peer's healthiness regarding these two aspects. The theoretical background of PRW originates from the optimization framework based on the generalized flow theory. To show PRW's applicability to a wide variety of P2P streaming solutions, we propose several parent selection algorithms guided by PRW under the single-tree, multi-tree, and mesh structures. Using MSN and PPLive traces, we find our algorithms to be able to achieve lower service disruption and lower peer rejection, compared to several existing heuristics and algorithms.