Ray is an open source project for parallel and distributed Python. This article was originally posted here. Parallel and distributed computing are a staple of modern applications. We need to leverage multiple cores or multiple machines to speed up applications or to run them at a large scale. The infrastructure for crawling the web and responding to search queries are not single-threaded programs running on someone’s laptop but rather collections of services that communicate and interact with one another. This post will describe how to use Ray to easily build applications that can scale from your laptop to a large cluster. Why Ray? Many tutorials explain how to use Python’s multiprocessing module. Unfortunately the multiprocessing module is severely limited in …
What Is the Role of Machine Learning in Databases?
(This article was authored by Sanjay Krishnan, Zongheng Yang, Joe Hellerstein, and Ion Stoica.) What is the role of machine learning in the design and implementation of a modern database system? This question has sparked considerable recent introspection in the data management community, and the epicenter of this debate is the core database problem of query optimization, where the database system finds the best physical execution path for an SQL query. The au courant research direction, inspired by trends in Computer Vision, Natural Language Processing, and Robotics, is to apply deep learning; let the database learn the value of each execution strategy by executing different query plans repeatedly (an homage to Google’s robot “arm farm”) rather through a pre-programmed analytical …
A History of Postgres
(crossposted from databeta.wordpress.com) The ACM began commissioning a series of reminiscence books on Turing Award winners. Thanks to hard work by editor Michael Brodie, the first one is Mike Stonebraker’s book, which just came out. I was asked to write the chapter on Postgres. I was one of the large and distinguished crew of grad students on the Postgres project, so this was fun. ACM in its wisdom decided that these books would be published in a relatively traditional fashion—i.e. you have to pay for them. The publisher, Morgan-Claypool, has this tip for students and ACM members: Please note that the Bitly link goes to a landing page where Students, ACM Members, and Institutions who have access to the ACM …
Confluo: Millisecond-level Queries on Large-scale Live Data
Confluo is a system for real-time distributed analysis of multiple data streams. Confluo simultaneously supports high throughput concurrent writes, online queries at millisecond timescales, and CPU-efficient ad-hoc queries via a combination of data structures carefully designed for the specialized case of multiple data streams, and an end-to-end optimized system design. We are excited to release Confluo as an open-source C++ project, comprising: Confluo’s data structure library, that supports high throughput ingestion of logs, along with a wide range of online (live aggregates, conditional trigger executions, etc.) and offline (ad-hoc filters, aggregates, etc.) queries, and, A Confluo server implementation, that encapsulates the data structures and exposes its operations via an RPC interface, along with client libraries in C++, Java and Python. …
MARVEL: Enabling Mobile Augmented Reality with Low Energy and Low Latency
This paper presents MARVEL, a mobile augmented reality (MAR) system which provides a notation display service with imperceptible latency (<100 ms) and low energy consumption on regular mobile devices. In contrast to conventional MAR systems, which recognize objects using image-based computations performed in the cloud, MARVEL mainly utilizes a mobile device’s local inertial sensors for recognizing and tracking multiple objects, while computing local optical flow and offloading images only when necessary. We propose a system architecture which uses local inertial tracking, local optical flow, and visual tracking in the cloud synergistically. On top of that, we investigate how to minimize the overhead for image computation and offloading. We have implemented and deployed a holistic prototype system in a commercial building …
Authors: Kaifei Chen, Tong Li, Hyung-Sin Kim, David Culler, Randy Katz
SQL Query Optimization Meets Deep Reinforcement Learning
We show that deep reinforcement learning is successful at optimizing SQL joins, a problem studied for decades in the database community. Further, on large joins, we show that this technique executes up to 10x faster than classical dynamic programs and 10,000x faster than exhaustive enumeration. This blog post introduces the problem and summarizes our key technique; details can be found in our latest preprint, Learning to Optimize Join Queries With Deep Reinforcement Learning. SQL query optimization has been studied in the database community for almost 40 years, dating all the way back from System R’s classical dynamic programming approach. Central to query optimization is the problem of join ordering. Despite the problem’s rich history, there is still a continuous stream …
System Architecture Directions for Post-SoC/32-bit Networked Sensors
The emergence of low-power 32-bit Systems-on-Chip (SoCs), which integrate a 32-bit MCU, radio, and flash, presents an opportunity to re-examine design points and trade-offs at all levels of the system architecture of networked sensors. To this end, we develop a post-SoC/32-bit design point called Hamilton, showing that using integrated components enables a ∼$7 core and shifts hardware modularity to design time. We study the interaction between hardware and embedded OSes, identifying that (1) post-SoC motes provide lower idle current (5.9 µA) than traditional 16-bit motes, (2) 32-bit MCUs are a major energy consumer (e.g., tick increases idle current >50 times), comparable to radios, and (3) thread-based concurrency is viable, requiring only 8.3 µs of context switch time. We design a …
Authors: Hyung-Sin Kim, Michael Andersen, Kaifei Chen, Sam Kumar, William J. Zhao, Kevin Ma, David Culler
Going Fast and Cheap: How We Made Anna Autoscale
Background: In an earlier blog post, we described a system called Anna, which used a shared-nothing, thread-per-core architecture to achieve lightning-fast speeds by avoiding all coordination mechanisms. Anna also used lattice composition to enable a rich variety of coordination-free consistency levels. The first version of Anna blew existing in-memory KVSes out of the water: Anna is up to 700x faster than Masstree, an earlier state-of-the-art research KVS, and up to 800x faster than Intel’s “lock-free” TBB hash table. You can find the previous blog post here and the full paper here. We refer to that version of Anna as “Anna v0.” In this post, we describe how we extended the fastest KVS in the cloud to be extremely cost-efficient and …
MLPerf: SPEC for ML
The RISE Lab at UC Berkeley today joins Baidu, Google, Harvard University, and Stanford University to announce a new benchmark suite for machine learning called MLPerf at the O’Reilly AI conference in New York City (see https://mlperf.org/). The MLPerf effort aims to build a common set of benchmarks that enables the machine learning (ML) field to measure system performance eventually for both training and inference from mobile devices to cloud services. We believe that a widely accepted benchmark suite will benefit the entire community, including researchers, developers, builders of machine learning frameworks, cloud service providers, hardware manufacturers, application providers, and end users. Historical Inspiration. We are motivated in part by the System Performance Evaluation Cooperative (SPEC) benchmark for general-purpose computing that drove rapid, …
Anna: A Crazy Fast, Super-Scalable, Flexibly Consistent KVS 🗺
This article cross-posted from the DataBeta blog. There’s fast and there’s fast. This post is about Anna, a key/value database design from our team at Berkeley that’s got phenomenal speed and buttery smooth scaling, with an unprecedented range of consistency guarantees. Details are in our upcoming ICDE18 paper on Anna. Conventional wisdom (or at least Jeff Dean wisdom) says that you have to redesign your system every time you scale by 10x. As researchers, we asked the counter-cultural question: what would it take to build a key-value store that would excel across many orders of magnitude of scale, from a single multicore box to the global cloud? Turns out this kind of curiosity can lead to a system with pretty interesting practical …
Design and Analysis of a Query Processor for Brick
Brick is a recently proposed metadata schema and ontology for describing building components and the relationships between them. It represents buildings as directed labeled graphs using the RDF data model. Using the SPARQL query language, building-agnostic applications query a Brick graph to discover the set of resources and relationships they require to operate. Latency-sensitive applications, such as user interfaces, demand response and modelpredictive control, require fast queries — conventionally less than 100ms. We benchmark a set of popular open-source and commercial SPARQL databases against three real Brick models using seven application queries and find that none of them meet this performance target. This lack of performance can be attributed to design decisions that optimize for queries over large graphs consisting …
Authors: Gabe Fierro,
SafeBricks: Shielding Network Functions in the Cloud
With the advent of network function virtualization (NFV), outsourcing network processing to the cloud is growing in popularity amongst enterprises and organizations. Such outsourcing, however, poses a threat to the security of the client’s traffic because the cloud is notoriously susceptible to attacks. We present SafeBricks, a system that shields generic network functions (NFs) from an untrusted cloud. SafeBricks ensures that only encrypted traffic is exposed to the cloud provider, and preserves the integrity of both traffic and the NFs. At the same time, it enables clients to reduce their trust in NF implementations by enforcing least privilege across NFs deployed in a chain. SafeBricks does not require changes to TLS, and safeguards the interests of NF vendors as well …
Authors: Rishabh Poddar, Chang Lan, Raluca Ada Popa, Sylvia Ratnasamy
Opaque: Secure Apache Spark SQL
As enterprises move to cloud-based analytics, the risk of cloud security breaches poses a serious threat. Encrypting data at rest and in transit is a major first step. However, data must still be decrypted in memory for processing, exposing it to any attacker who can observe memory contents. This is a challenging problem because security usually implies a tradeoff between performance and functionality. Cryptographic approaches like fully homomorphic encryption provide full functionality to a system, but are extremely slow. Systems like CryptDB utilize lighter cryptographic primitives to provide a practical database, but are limited in functionality. Recent developments in trusted hardware enclaves (such as Intel SGX) provide a much needed alternative. These hardware enclaves provide hardware-enforced shielded execution that allows …
Announcing Ground v0.1
We’re excited to be releasing v0.1 of the Ground project! Ground is a data context service. It is a central repository for all the information surrounding the use of data in an organization. Ground concerns itself with what data an organization has, where that data is, who (both human beings and software systems) is touching that data, and how that data is being modified and described. Above all, Ground aims to be an open-source, vendor neutral system that provides users an unopinionated metamodel and set of APIs that allow them to think about and interact with data context generated in their organization. Ground has many use cases, but we’re focused on two specific ones at present: Data Inventory: large organizations …
Reinforcement Learning brings together RISELab and Berkeley DeepDrive for a joint mini-retreat
On May 2, RISELab and the Berkeley DeepDrive (BDD) lab held a joint, largely student-driven mini-retreat. The event was aimed at exploring research opportunities at the intersection of the BDD and RISE labs. The topical focus of the mini-retreat was emerging AI applications, such as Reinforcement Learning (RL), and computer systems to support such applications. Trevor Darrell kicked off the event with an introduction to the Berkeley DeepDrive lab, followed by Ion Stoica’s overview of RISE. The event offered a great opportunity for researchers from both labs to exchange ideas about their ongoing research activity and discover points of collaboration. Philipp Moritz started the first student talk session with an update on Ray — a distributed execution framework for emerging …
RISELab Announces 3 Open Source Releases
Part of the Berkeley tradition—and the RISELab mission—is to release open source software as part of our research agenda. Six months after launching the lab, we’re excited to announce initial v0.1 releases of three RISElab open-source systems: Clipper, Ground and Ray. Clipper is an open-source prediction-serving system. Clipper simplifies deploying models from a wide range of machine learning frameworks by exposing a common REST interface and automatically ensuring low-latency and high-throughput predictions. In the 0.1 release, we focused on reliable support for serving models trained in Spark and Scikit-Learn. In the next release we will be introducing support for TensorFlow and Caffe2 as well as online-personalization and multi-armed bandits. We are providing active support for early users and will be following Github issues …
Declarative Heterogeneity Handling for Datacenter and ML Resources
Challenge Heterogeneity in datacenter resources has become the fact of life. We identify and categorize a number of different types of heterogeneity. When talking about heterogeneity, we generally refer to static or dynamic attributes associated with individual resources. Previously the levels of heterogeneity were fairly benign and limited to a few different types of processor architectures. Now, however, it has become a common trend to deploy hardware accelerators (e.g., Tesla K40/K80, Google TPU, Intel Xeon PHI) and even FPGAs (e.g., Microsoft Catapult project). Nodes themselves are connected with heterogeneous interconnects, oftentimes with more than one interconnect option available (e.g., 40Gbps ethernet backbone, Infiniband, FPGA torus topology). The workloads we consolidate on top of this diverse hardware differ vastly in their success metrics (completion …
Grail Quest: A New Proposal for Hardware-assisted Garbage Collection
Many big data systems are written in garbage-collected languages and GC has a substantial impact on throughput, responsiveness and predicability of these systems. However, despite decades of research, there is still no “Holy Grail” of GC: a collector with no measurable impact, even on real-time applications. Such a collector needs to achieve freedom from pauses, high GC throughput and good memory utilization, without slowing down application threads or using substantial amounts of compute resources. In this paper, we propose a step towards this elusive goal by reviving the old idea of moving GC into hardware. We discuss the trends that make it the perfect time to revisit this approach and present the design of a hardware-assisted GC that aims to …
Authors: Martin Maas, Krste Asanovic, John Kubiatowicz
Serverless Scientific Computing
For many scientific and engineering users, cloud infrastructure remains challenging to use. While many of their use cases are embarrassingly parallel, the challenges involved in provisioning and using stateful cloud services keep them trapped on their laptops or large shared workstations. Before getting started, a new cloud user confronts a bewildering number of choices. First, what instance type do they need ? How do they make the compute/memory tradeoff? How large do they want their cluster to be? Can they take advantage of dynamic market-based instances (spot instances) that can disappear at any time? What if they have 1000 small jobs, each of which takes a few minutes — what’s the most cost-effective way of allocating servers? What host operating …
SparkR: Scaling R Programs with Spark
R is a popular statistical programming language with a number of extensions that support data processing and machine learning tasks. However, interactive data analysis in R is usually limited as the R runtime is single threaded and can only process data sets that fit in a single machine’s memory. We present SparkR, an R package that provides a frontend to Apache Spark and uses Spark’s distributed computation engine to enable large scale data analysis from the R shell. We describe the main design goals of SparkR, discuss how the high-level DataFrame API enables scalable computation and present some of the key details of our implementation.
Authors: Shivaram Venkataraman, Ali Ghodsi, Ion Stoica
MiniCrypt: Reconciling Encryption and Compression for Big Data Stores.
More and more applications and web services generate larger and larger amounts of confidential data, such as user and financial data. On one hand, these systems must use encryption to ensure confidentiality, while on the other hand, they want to use compression to reduce costs and increase performance. Unfortunately, encryption and compression are in tension, leading many existing systems to support one but not the other. We propose MiniCrypt, the first big data keyvalue store that reconciles encryption and compression, without compromising performance. At the core of MiniCrypt is an observation on data compressibility trends in key-value stores, which enables grouping key-value pairs in small key packs, together with a set of new distributed systems techniques for retrieving, updating, merging …
Authors: Wenting Zheng, Raluca Ada Popa, Ion Stoica, Rachit Agarwal, Frank Li
Opaque: An Oblivious and Encrypted Distributed Analytics Platform.
As enterprises move to cloud-based analytics, the risk of cloud security breaches poses a serious threat. Encrypting data at rest and in transit is a major first step. However, data must still be decrypted in memory for processing, exposing it to an attacker who has compromised the operating system or hypervisor. Trusted hardware such as Intel SGX has recently become available in latest-generation processors. Such hardware enables arbitrary computation on encrypted data while shielding it from a malicious OS or hypervisor. However, it still suffers from a significant side channel: access pattern leakage. We present Opaque, a package for Apache Spark SQL that enables very strong security for SQL queries: data encryption, computation verification, and access pattern leakage protection (a.k.a. …
Authors: Wenting Zheng, Raluca Ada Popa, Ion Stoica, Joseph Gonzalez, Ankur Dave, Jethro Beekman
Proteus: agile ML elasticity through tiered reliability in dynamic resource markets
Many shared computing clusters allow users to utilize excess idle resources at lower cost or priority, with the proviso that some or all may be taken away at any time. But, exploiting such dynamic resource availability and the often fluctuating markets for them requires agile elasticity and effective acquisition strategies. Proteus aggressively exploits such transient revocable resources to do machine learning (ML) cheaper and/or faster. Its parameter server framework, AgileML, efficiently adapts to bulk additions and revocations of transient machines, through a novel 3-stage active-backup approach, with minimal use of more costly non-transient resources. Its BidBrain component adaptively allocates resources from multiple EC2 spot markets to minimize average cost per work as transient resource availability and cost change over time. …
Authors: Aaron Harlap, Alexey Tumanov, Andrew Chung, Gregory R. Ganger, Phil Gibbons
Morpheus: Towards Automated SLOs for Enterprise Clusters
Modern resource management frameworks for largescale analytics leave unresolved the problematic tension between high cluster utilization and job’s performance predictability—respectively coveted by operators and users. We address this in Morpheus, a new system that: 1) codifies implicit user expectations as explicit Service Level Objectives (SLOs), inferred from historical data, 2) enforces SLOs using novel scheduling techniques that isolate jobs from sharing-induced performance variability, and 3) mitigates inherent performance variance (e.g., due to failures) by means of dynamic reprovisioning of jobs. We validate these ideas against production traces from a 50k node cluster, and show that Morpheus can lower the number of deadline violations by 5x to 13x, while retaining cluster-utilization, and lowering cluster footprint by 14% to 28%. We demonstrate …
Authors: C. Curino, I. Menache, S. Narayanamurthy, Alexey Tumanov, J. Yaniv, R. Mavlyutov, I. Goiri, S. Krishnan, J. Kulkarni, S. Rao
Clipper: A Low-Latency Online Prediction Serving System
Machine learning is being deployed in a growing number of applications which demand real-time, accurate, and robust predictions under heavy query load. However, most machine learning frameworks and systems only address model training and not deployment. In this paper, we introduce Clipper, a general-purpose low-latency prediction serving system. Interposing between end-user applications and a wide range of machine learning frameworks, Clipper introduces a modular architecture to simplify model deployment across frameworks and applications. Furthermore, by introducing caching, batching, and adaptive model selection techniques, Clipper reduces prediction latency and improves prediction throughput, accuracy, and robustness without modifying the underlying machine learning frameworks. We evaluate Clipper on four common machine learning benchmark datasets and demonstrate its ability to meet the latency, accuracy, …
Authors: Dan Crankshaw, Xin Wang, Giulio Zhou, Michael J. Franklin, Joseph Gonzalez, Ion Stoica