SnailTrail: Generalizing Critical Paths for Online Analysis of Distributed Dataflows


Moritz Hoffmann, Andrea Lattuada, John Liagouris, Vasiliki Kalavri, Desislava Dimitrova, Sebastian Wicki, Zaheer Chothia, and Timothy Roscoe, ETH Zurich


We rigorously generalize critical path analysis (CPA) to long-running and streaming computations and present SnailTrail, a system built on Timely Dataflow, which applies our analysis to a range of popular distributed dataflow engines. Our technique uses the novel metric of critical participation, computed on time-based snapshots of execution traces, that provides immediate insights into specific parts of the computation. This allows SnailTrail to work online in real-time, rather than requiring complete offline traces as with traditional CPA. It is thus applicable to scenarios like model training in machine learning, and sensor stream processing.

SnailTrail assumes only a highly general model of dataflow computation (which we define) and we show it can be applied to systems as diverse as Spark, Flink, TensorFlow, and Timely Dataflow itself. We further show with examples from all four of these systems that SnailTrail is fast and scalable, and that critical participation can deliver performance analysis and insights not available using prior techniques.

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@inproceedings {211257,
author = {Moritz Hoffmann and Andrea Lattuada and John Liagouris and Vasiliki Kalavri and Desislava Dimitrova and Sebastian Wicki and Zaheer Chothia and Timothy Roscoe},
title = {{SnailTrail}: Generalizing Critical Paths for Online Analysis of Distributed Dataflows},
booktitle = {15th USENIX Symposium on Networked Systems Design and Implementation (NSDI 18)},
year = {2018},
isbn = {978-1-939133-01-4},
address = {Renton, WA},
pages = {95--110},
url = {},
publisher = {USENIX Association},
month = apr

Presentation Video