CSC4700-Tasks & Concurrency (2nd Part)

About this Video

• Video Title: CSC4700-Tasks & Concurrency (2nd Part)
• Channel: Stellar at LSU
• Speakers: (Speaker name not explicitly mentioned in transcript, but presumed to be a professor at LSU)
• Duration: 01:10:11

Introduction

This video lecture continues a discussion on task-based parallelism in C++, focusing on asynchronous parallelism and unique methods for mitigating scalability issues in fork-join parallelism. The lecturer introduces extensions to standard futures implemented in HPX, a C++ library developed at LSU, to improve parallel application writing.

Key Takeaways

1. Mitigating Fork-Join Parallelism Scalability Issues: The lecture addresses the scalability problems of fork-join parallelism, particularly when iterations take varying amounts of time. A novel method to improve load balancing is presented.
2. HPX Library Introduction: HPX, an open-source C++ library, is introduced as a tool for building shared memory and distributed parallel applications with uniform APIs. It's highlighted as compatible with the C++ standard and easily integrated using CMake.
3. Extensions to Standard Futures: The lecture details extensions to standard futures in HPX, including creating ready futures, compositional facilities (sequential and parallel composition using then and when_all), and asynchronous parallel algorithms (dataflow).
4. co_await Keyword for Simplified Asynchronous Programming: The co_await keyword in C++17 is presented as a way to simplify asynchronous programming, enabling the writing of sequential-looking code that implicitly manages asynchronous operations and dependencies.
5. Futurization Technique: The lecture introduces "futurization," a technique to transform sequential code into a futurized, fully parallelized version by creating a dependency tree of futures, improving performance by overlapping tasks and avoiding synchronization delays.