• stream processing
• self-adaptive software
• parallelism abstractions
• parallel programming
• autonomic systems

Nowadays, a significant part of computing systems and real-world applications demand parallelism to accelerate their executions. Although high-level and structured parallel programming aims to facilitate parallelism exploitation, there are still issues to be addressed to improve existing parallel programming abstractions. Usually, application developers still have to set non-intuitive or complex parallelism configurations. In this context, self-adaptation is a potential alternative to provide a higher-level of autonomic abstractions and runtime responsiveness in parallel executions. However, a recurrent problem is that self-adaptation is still limited in terms of flexibility, efficiency, and abstractions. For instance, there is a lack of mechanisms to apply adaptation actions and efficient decision-making strategies to decide which configurations to be enforced at run-time. In this work, we are interested in abstractions achievable with self-adaptation transparently managing the executions while the parallel programs are running (at run-time). Our main goals are to increase the adaptation space to be more representative of real-world applications and make self-adaptation more efficient with comprehensive evaluation methodologies, which can provide use-cases demonstrating the true potentials of self-adaptation.
Therefore, this doctoral dissertation provides the following scientific contributions: I) An SLR providing a taxonomy of the state-of-the-art. II) A conceptual framework to support designing and abstracting the decision-making process within self-adaptive solutions, such a conceptual framework is then employed in the technical contributions to assist in making the solutions more modular and potentially generalizable. III) Mechanisms and strategies for self-adaptive replicas in applications with single and multiple parallel stages, supporting multiple customizable non-functional requirements. IV) Mechanism, strategy, and optimizations for self-adaptation of Parallel Patterns/applications' graphs topologies. We apply the proposed solutions to the context of stream processing applications, a representative paradigm present in several real-world applications that compute data flowing in the form of streams (e.g., video feeds, image, and data analytics). A part of the proposed solutions is evaluated with SPar and another part with the FastFlow programming framework.
The results demonstrate that self-adaptation can provide efficient parallelism abstractions and autonomous responsiveness at run-time, yet achieve a competitive performance w.r.t. the best static executions. Moreover, when appropriate, we compare state-of-the-art solutions and demonstrate that our highly optimized decision-making strategies achieve significant performance and efficiency gains.