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

作　　者：Yun TENG Zhiyue LI Jing HUANG Guangyan ZHANG 

机构地区：[1]College of Computer Science and Technology,Jilin University,Changchun 130012,China [2]Department of Computer Science and Technology,Tsinghua University,Beijing 100084,China [3]Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education,Jilin University,Changchun 130012,China [4]Beijing National Research Center for Information Science and Technology(Tsinghua University),Beijing 100084,China

出　　处：《Frontiers of Information Technology & Electronic Engineering》2022年第11期1646-1657,共12页信息与电子工程前沿（英文版）

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)。

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.

关 键 词：Erasure code In-memory system Node fail-slow Small write Tail latency 

分 类 号：TP302[自动化与计算机技术—计算机系统结构]