funcX: A Federated Function Serving Fabric for Science

Exploding data volumes and velocities, new computational methods and platforms, and ubiquitous connectivity demand new approaches to computation in the sciences. These new approaches must enable computation to be mobile, so that, for example, it can occur near data, be triggered by events (e.g., arrival of new data), be offloaded to specialized accelerators, or run remotely where resources are available. They also require new design approaches in which monolithic applications can be decomposed into smaller components, that may in turn be executed separately and on the most suitable resources. To address these needs we present funcX---a distributed function as a service (FaaS) platform that enables flexible, scalable, and high performance remote function execution. funcX's endpoint software can transform existing clouds, clusters, and supercomputers into function serving systems, while funcX's cloud-hosted service provides transparent, secure, and reliable function execution across a federated ecosystem of endpoints. We motivate the need for funcX with several scientific case studies, present our prototype design and implementation, show optimizations that deliver throughput in excess of 1 million functions per second, and demonstrate, via experiments on two supercomputers, that funcX can scale to more than more than 130000 concurrent workers.Comment: Accepted to ACM Symposium on High-Performance Parallel and Distributed Computing (HPDC 2020). arXiv admin note: substantial text overlap with arXiv:1908.0490

Rise of the Planet of Serverless Computing: A Systematic Review

Serverless computing is an emerging cloud computing paradigm, being adopted to develop a wide range of software applications. It allows developers to focus on the application logic in the granularity of function, thereby freeing developers from tedious and error-prone infrastructure management. Meanwhile, its unique characteristic poses new challenges to the development and deployment of serverless-based applications. To tackle these challenges, enormous research efforts have been devoted. This paper provides a comprehensive literature review to characterize the current research state of serverless computing. Specifically, this paper covers 164 papers on 17 research directions of serverless computing, including performance optimization, programming framework, application migration, multi-cloud development, testing and debugging, etc. It also derives research trends, focus, and commonly-used platforms for serverless computing, as well as promising research opportunities

Benchmarking Resource Management For Serverless Computing

Serverless computing is a way in which users or companies can build and run applications and services without having to worry about acquiring or maintaining servers and their software stacks. This new technology is a significant innovation because server management incurs a large amount of overhead and can be very complex and difficult to work with. The serverless model also allows for fine-grain billing and demand resource allocation, allowing for better scalability and cost reduction. Academic researchers and industry practitioners agree that serverless computing is an amazing innovation, but it introduces new challenges. The algorithms and protocols currently deployed for virtual server optimization in traditional cloud computing environments are not able to simultaneously achieve low latency, high throughput, and fine-grained scalability while maintaining low cost for the cloud service providers. Furthermore, in the serverless computing paradigm, computation units (i.e., functions) are stateless. Applications, specified through function workflows, do not have control over specific states or their scheduling and placement, which can sometimes lead to significant latency increases and some opportunities to optimize the usage of physical servers. Overcoming these challenges highlights some of the tension between giving programmers control and allowing providers to optimize automatically. This research identifies some of the challenges in exploring new resource management approaches for serverless computing (more specifically, FaaS) as well as attempts to deal with one of these challenges. Our experimental approach includes the deployment of an open-source serverless function framework, OpenFaaS. We focus on faasd, a more lightweight variant of OpenFaaS. Faasd was chosen over the normal OpenFaaS due to not having the higher complexity and cost of Kubernetes. As researchers in academia and industry develop new approaches for optimizing the usage of CPU, memory, and I/O for serverless platforms, the community needs to establish benchmark workloads for evaluating proposed methods. Several research groups have proposed benchmark suites in the last two years, and many others are still in development. A commonality among these benchmark tools is their complexity; for junior researchers without experience in the deployment of distributed systems, a lot of time and effort goes into deploying the benchmarking, hindering their progress in evaluating newly proposed ideas. In our work, we demonstrate that even well-regarded proposals still introduce deficiencies and deployment challenges, proposing that a simplified, constrained benchmark can be useful in preparing execution environments for the experimental evaluation with serverless services

BeeFlow: Behavior Tree-based Serverless Workflow Modeling and Scheduling for Resource-Constrained Edge Clusters

Serverless computing has gained popularity in edge computing due to its flexible features, including the pay-per-use pricing model, auto-scaling capabilities, and multi-tenancy support. Complex Serverless-based applications typically rely on Serverless workflows (also known as Serverless function orchestration) to express task execution logic, and numerous application- and system-level optimization techniques have been developed for Serverless workflow scheduling. However, there has been limited exploration of optimizing Serverless workflow scheduling in edge computing systems, particularly in high-density, resource-constrained environments such as system-on-chip clusters and single-board-computer clusters. In this work, we discover that existing Serverless workflow scheduling techniques typically assume models with limited expressiveness and cause significant resource contention. To address these issues, we propose modeling Serverless workflows using behavior trees, a novel and fundamentally different approach from existing directed-acyclic-graph- and state machine-based models. Behavior tree-based modeling allows for easy analysis without compromising workflow expressiveness. We further present observations derived from the inherent tree structure of behavior trees for contention-free function collections and awareness of exact and empirical concurrent function invocations. Based on these observations, we introduce BeeFlow, a behavior tree-based Serverless workflow system tailored for resource-constrained edge clusters. Experimental results demonstrate that BeeFlow achieves up to 3.2X speedup in a high-density, resource-constrained edge testbed and 2.5X speedup in a high-profile cloud testbed, compared with the state-of-the-art.Comment: Accepted by Journal of Systems Architectur

RFaaS: RDMA-Enabled FaaS Platform for Serverless High-Performance Computing

The rigid MPI programming model and batch scheduling dominate high-performance computing. While clouds brought new levels of elasticity into the world of computing, supercomputers still suffer from low resource utilization rates. To enhance supercomputing clusters with the benefits of serverless computing, a modern cloud programming paradigm for pay-as-you-go execution of stateless functions, we present rFaaS, the first RDMA-aware Function-as-a-Service (FaaS) platform. With hot invocations and decentralized function placement, we overcome the major performance limitations of FaaS systems and provide low-latency remote invocations in multi-tenant environments. We evaluate the new serverless system through a series of microbenchmarks and show that remote functions execute with negligible performance overheads. We demonstrate how serverless computing can bring elastic resource management into MPI-based high-performance applications. Overall, our results show that MPI applications can benefit from modern cloud programming paradigms to guarantee high performance at lower resource costs

QoS-Aware Resource Management for Multi-phase Serverless Workflows with Aquatope

Multi-stage serverless applications, i.e., workflows with many computation and I/O stages, are becoming increasingly representative of FaaS platforms. Despite their advantages in terms of fine-grained scalability and modular development, these applications are subject to suboptimal performance, resource inefficiency, and high costs to a larger degree than previous simple serverless functions. We present Aquatope, a QoS-and-uncertainty-aware resource scheduler for end-to-end serverless workflows that takes into account the inherent uncertainty present in FaaS platforms, and improves performance predictability and resource efficiency. Aquatope uses a set of scalable and validated Bayesian models to create pre-warmed containers ahead of function invocations, and to allocate appropriate resources at function granularity to meet a complex workflow's end-to-end QoS, while minimizing resource cost. Across a diverse set of analytics and interactive multi-stage serverless workloads, Aquatope significantly outperforms prior systems, reducing QoS violations by 5x, and cost by 34% on average and up to 52% compared to other QoS-meeting methods

Adapting Microservices in the Cloud with FaaS

This project involves benchmarking, microservices and Function-as-a-service (FaaS) across the dimensions of performance and cost. In order to do a comparison this paper proposes a benchmark framework

Topology-based Scheduling in Serverless Computing Platforms

In the past few years, Function as a Service (FaaS) solutions, and Serverless computing in general, have become a significant topic both in terms of general interest and research effort. Allowing users to run stateless code in the cloud without worrying about the underlying infrastructure for scheduling, management and scaling, the ease of use of these approaches still comes with various trade-offs and challenges. In this thesis, the issue of data locality is observed, using an extension of the Apache OpenWhisk framework to provide users the ability to select the node they wish to use to schedule some of their functions, allowing the code to be run closer to the data it manipulates. Additionally, a topology-based scheduling approach is implemented for the framework, where load balancers are instructed to prioritize nodes in their same topological zone; this way, users can specify a preferred load balancer for different functions, with no need to know the position and name of all other nodes in the cluster. This modified version of the OpenWhisk framework is then compared with the standard OpenWhisk implementation, along with two other serverless frameworks, Fission and OpenFaaS, using a test suite composed of different use cases, using both existing projects from the Wonderless dataset and custom-built functions targeting different aspects of the paradigm. The role of data locality considerations and topology-based policies is analyzed, showing their importance in a multi-zone cluster with nodes in various geographical locations, where latency between them and the remote data used by the functions can be significant