Aleksey Charapko

  • One Page Summary. Aegean: Replication beyond the client-server model

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    One Page Summary.  Aegean: Replication beyond the client-server model This paper builds o n a key observation about the operation of complex distributed applications. Namely, microservice style of application rarely follows a simple client-server architecture, where a client makes a request and the server (or servers) respond to a request. Instead, many applications often use…

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  • One Page Summary: Ring Paxos

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    This paper (Ring Paxos: A high-throughput atomic broadcast protocol) has been out for quite some time, but it addresses a problem still relevant in many distributed consensus protocols. Ring Paxos aims to reduce the communication load in the Paxos cluster and provide better scalability. As we have shown in our SIGMOD 2019 paper, communication is…

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  • Paper Summary: Bolt-On Global Consistency for the Cloud

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    This paper appeared in SOCC 2018, but caught my Paxos attention only recently. The premise of the paper is to provide strong consistency in a heterogeneous storage system spanning multiple cloud providers and storage platforms. Going across cloud providers is challenging, since storage services at different clouds cannot directly talk to each other and replicate the…

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  • Keep The Data Where You Use It

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    As trivial as it sounds, but keeping the data close to where it is consumed can drastically improve the performance of the large globe-spanning cloud applications, such as social networks, ecommerce and IoT. These applications rely on some database systems to make sure that all the data can be accessed quickly. The de facto method…

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  • Looking at State and Operational Consistency

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    Recently I rediscovered the “The many faces of consistency” paper by Marcos Aguilera and Doug Terry. When I first read the paper two years ago, I largely dismissed it as trivial, and, oh boy, now I realized how wrong I was at that time.  It is easy to read for sure, and may appear as…

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  • Python, Numpy and a Programmer Error: Story of a Bizarre Bug

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    While recently working on my performance analysis for Paxos-style protocols, I uncovered some weird quirks about python and numpy. Ultimately, the problem was with my code, however the symptoms of the issue looked extremely bizarre at first. Modeling WPaxos required doing a series of computations with numpy. In each step, I used numpy to do…

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  • One Page Summary: “PaxosStore: High-availability Storage Made Practical in WeChat”

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    PaxosStore paper, published in VLDB 2017, describes the large scale, multi-datacenter storage system used in WeChat. As the name may suggest, it uses Paxos to provide storage consistency. The system claims to provide storage for many components of the WeChat application, with 1.5TB of traffic per day and tens of thousands of queries per second…

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  • Modeling Paxos Performance in Wide Area – Part 3

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    Earlier I looked at modeling paxos performance in local networks, however nowadays people (companies) use paxos and its flavors in the wide area as well. Take Google Spanner and CockroachDB as an example. I was naturally curious to expand my performance model into wide area networks as well. Since our lab worked on WAN coordination…

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  • Modeling Paxos Performance – Part 2

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    In the previous posts I started to explore node-scalability of paxos-style protocols. In this post I will look at processing overheads that I estimate with the help of a queue or a processing pipeline. I show how these overheads cap the performance and affect the latency at different cluster loads. I look at the scalability for…

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  • Paxos Performance Modeling – Part 1.5

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    This post is a quick update/conclusion to the part 1. So, does the network variations make any impact at all? In the earlier simulation I showed some small performance degradation going from 3 to 5 nodes. The reality is that for paxos, network behavior makes very little difference on scalability, and in some cases no difference at…

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