Short Tail:taming tail latency for erasure-code-based in-memory systems

作     者：Yun TENG Zhiyue LI Jing HUANG Guangyan ZHANG Yun TENG;Zhiyue LI;Jing HUANG;Guangyan ZHANG

作者机构：College of Computer Science and TechnologyJilin UniversityChangchun 130012China Department of Computer Science and TechnologyTsinghua UniversityBeijing 100084China Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of EducationJilin UniversityChangchun 130012China Beijing National Research Center for Information Science and Technology(Tsinghua University)Beijing 100084China 

出 版 物：《Frontiers of Information Technology & Electronic Engineering》 (信息与电子工程前沿（英文版）)

年 卷 期：2022年第23卷第11期

页      面：1646-1657页

核心收录：

学科分类：0808[工学-电气工程] 08[工学] 0835[工学-软件工程] 081201[工学-计算机系统结构] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China(No.62025203) the Changchun Key Scientific and Technological Research and Development Project,China(No.21ZGN30)。 

主　　题：Erasure code In-memory system Node fail-slow Small write Tail latency 

摘      要：In-memory systems with erasure coding(EC)enabled are widely used to achieve high performance and data availability.However,as the scale of clusters grows,the server-level fail-slow problem is becoming increasingly frequent,which can create long tail latency.The influence of long tail latency is further amplified in EC-based systems due to the synchronous nature of multiple EC sub-operations.In this paper,we propose an EC-enabled in-memory storage system called ShortTail,which can achieve consistent performance and low latency for both reads and writes.First,ShortTail uses a lightweight request monitor to track the performance of each memory node and identify any fail-slow node.Second,ShortTail selectively performs degraded reads and redirected writes to avoid accessing fail-slow nodes.Finally,ShortTail posts an adaptive write strategy to reduce write amplification of small writes.We implement ShortTail on top of Memcached and compare it with two baseline systems.The experimental results show that ShortTail can reduce the P99 tail latency by up to 63.77%;it also brings significant improvements in the median latency and average latency.