Aleksey Charapko

  • The First Datastore-driven Vehicle

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    It is not a secret that procrastination is the favorite activity of most PhD students. I have been procrastinating today, even though my advisor probably wants me to keep writing.  In the midst of my procrastination, I thought: “Why are there self-driving vehicles, but no database-driven vehicles?” As absurd as it sounds, I gave it…

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  • One Page Summary: “Musketeer: all for one, one for all in data processing systems”.

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    Many distributed computation platforms and programming frameworks exist today, and new ones constantly popping out from the industry and academia.  Some platforms are domain specific, such as TensorFlow for machine learning. Others, like Hadoop and Naiad are more general, and this generality allows for sophisticated and specialized programming abstractions to be built on top. So…

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  • One Page Summary: “Slicer: Auto-Sharding for Datacenter Applications”

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    One of the questions engineers of large distributed system must answer is “where to compute”. This is a big and important question, as we do not want to send a request originating in the US to some server in Australia. It simply makes no sense to incur the communication overhead if there are resources available…

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  • Monitoring with Retroscope: Detecting Invariant Violations

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    Earlier I briefly mentioned Retroscope, our distributed snapshot library that makes taking non-blocking, unplanned consistent global distributed snapshots possible. However, these snapshots are only good if we know how to use them well. Of course the most obvious use case is just a data backup, and despite it being an important application for snapshots, I…

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  • One Page Summary: Incremental, Iterative Processing with Timely Dataflow

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    This paper describes Naiad distributed computation system. Naiad uses dataflow model to represent the computations, but it aims to be a general dataflow framework in contrast to other specialized approaches such as TensorFlow. Similarly to other dataflow systems, the computations are represented as graphs, where vertices represent data and operations and edges carry the data…

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  • Is Java Fast Enough for Distributed Applications?

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    Lots of modern distributed systems are built with Java programming language, and consequently use Java Virtual Machine (JVM) as their execution environment. The list of such systems is rather large: Hadoop, Spark, HBase, Cassandra, Voldemort, ZooKeeper, BookKeeper, Kafka, and the list goes on and on. But is JVM fast enough for these systems? Anyone who…

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  • Globally Consistent Distributed Snapshots with Retroscope

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    Taking a consistent snapshot of a distributed system is no trivial task for the reasons of asynchrony between the nodes in the system. As the state of each machine changes in response to incoming external messages or internal events, each node may produce a log of such state changes. With the log abstraction, the problem…

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  • Gorilla – Facebook’s Cache for Time Series Data

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    Facebook operates a huge infrastructure that needs to be constantly monitored for performance and stability. Such monitoring collects huge amounts of data that must be easily accessible to various diagnosis and anomaly detection tools in order to quickly identify and react to possible issues. Many of such parameters can be represented as real-valued time series.…

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  • The Light of Voldemort

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    Few month ago I showcased how a single server of Voldemort key-value store sounds.  Sonification is a valid way to monitor systems, and has been used a lot in real applications. Geiger counter would be one of the most well-known examples of a sonified application. In some cases sonification may be the preferred form of…

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  • Pivot Tracing Part 2

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    After looking more at Pivot Tracing tool described in my earlier post, I asked myself about the limitations of such monitoring approach. Pivot tracing is not a universal tool, so it appears that there are few problems it does not address well enough. The basic idea of the Pivot Tracing is to collect the information…

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