International Business Machines Corporation

Google Inc.

Peter H Hochschild

Rama Krishna Govindaraju

Wilson Cheng-Yi Hsieh

Monty Montague Denneau

Alexander Lloyd

Michael James Boyer Epstein

Balaram Sinharoy

Robert Edman Felderman

Ravi Kumar Arimilli

Bruce Gerard Mealey

Satya Prakash Sharma

Richard A Swetz

Sean Quinlan

Craig Brian Stunkel

Kevin J Gildea

Henry Stanley Warren, Jr

Robert Sidney Blackmore

Ashutosh Misra

Carl Alfred Bender

Piyush Chaudhary

Donald G Grice

Fu Chung Chang

Jay Robert Herring

John Scott Houston

Leonard W Helmer, Jr

Steven J Martin

Jason E Goscinski

Bruce D Gavril

Chulho Kim

Narasimha R Adiga

Rajeev Sivaram

Ramakrishnan Rajamony

Robert William Wisniewski

Peter Kenneth Szwed

Ahmed Gheith

Hanhong Xue

Xiaowei Shen

Hazim Shafi

Patrick Joseph Bohrer

Guenter E Roeck

Jang-Soo Lee

Hain-Ching Liu

Roy Michael Bannon

Deryck X Hong

Patricia E Heywood

Yun-Pong Huang

Rama J Govindaraju

Daniel K Beece

Cynthia A Trempel

Allan Rappaport

Sridhar Raman

Yuqing Zhu

The present technology proposes techniques for generating globally coherent timestamps. This technology may allow distributed systems to causally order transactions without incurring various types of communication delays inherent in explicit synchronization. By globally deploying a number of time masters that are based on various types of time references, the time masters may serve as primary time references. Through an interactive interface, the techniques may track, calculate and record data relative to each time master thus providing the distributed systems with causal timestamps.

Generating globally coherent timestamps

The present technology proposes techniques for ensuring globally consistent transactions. This technology may allow distributed systems to ensure the causal order of read and write transactions across different partitions of a distributed database. By assigning causally generated timestamps to the transactions based on one or more globally coherent time services, the timestamps can be used to preserve and represent the causal order of the transactions in the distributed system. In this regard, certain transactions may wait for a period of time after choosing a timestamp in order to delay the start of any second transaction that might depend on it. The wait may ensure that the effects of the first transaction are not made visible until its timestamp is guaranteed to be in the past. This may ensure that a consistent snapshot of the distributed database can be determined for any past timestamp.

Ensuring globally consistent transactions

The present disclosure provides for automatically detecting errors, such as SDC, in a multi-core computing environment. For example, cores may run in an error detection mode, in which multiple cores repeat the same execution of instructions and the results are compared. Based on the results, it may be determined whether one of the cores is failing.

Pseudo lock-step execution across CPU cores

Throughput is preserved in a distributed system while maintaining concurrency by pushing a commit wait period to client commit paths and to future readers. As opposed to servers performing commit waits, the servers assign timestamps, which are used to ensure that causality is preserved. When a server executes a transaction that writes data to a distributed database, the server acquires a user-level lock, and assigns the transaction a timestamp equal to a current time plus an interval corresponding to bounds of uncertainty of clocks in the distributed system. After assigning the timestamp, the server releases the user-level lock. Any client devices, before performing a read of the written data, must wait until the assigned timestamp is in the past.

High-throughput algorithm for multiversion concurrency control with globally synchronized time

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New York, NY, United States of America

Peter H Hochschild