Abstract. In this paper we describe an assume/guarantee based execution constraints synthesis algorithm for concurrent threads executing on parallel platforms. Threads are loops which can have several control points, such as the activation of loop iterations and the interaction with other threads. Real-time applications such as multimedia applications are usually specified using this kind of concurrent interacting threads. The proposed compositional algorithm outputs a set of sufficient constraints on the control points in order to meet timing objectives. The paper first presents the timed system model we use to specify such applications. Then, the constraints synthesis algorithm is presented and illustrated on a real-time video application.