concurrency

HPX V1.5 released -- STE||AR Group

The STE||AR Group has released V1.5 of HPX -- A C++ Standard library for parallelism and concurrency.

HPX V1.5 Released

The newest version of HPX (V1.5) is now available for download! This is a big release with many changes and improvements. We have added numerous new features, adapted a lot of facilities to improve C++20 conformance. We have also continued our work on modularizing and making HPX lighter, improved its usability, stability, and performance. Please see here for full release notes.

    HPX is a general purpose parallel C++ runtime system for applications of any scale. It implements all of the related facilities as defined by the C++ Standard. As of this writing, HPX provides the only widely available open-source implementation of the new C++17 parallel algorithms. Additionally, HPX implements functionalities proposed as part of the ongoing C++ standardization process, such as large parts of the features related parallelism and concurrency as specified by the upcoming C++20 Standard, the C++ Concurrency TS, Parallelism TS V2, data-parallel algorithms, executors, and many more. It also extends the existing C++ Standard APIs to the distributed case (e.g. compute clusters) and for heterogeneous systems (e.g. GPUs).

    HPX seamlessly enables a new Asynchronous C++ Standard Programming Model that tends to improve the parallel efficiency of our applications and helps reducing complexities usually associated with parallelism and concurrency.

 

There Is A New Future -- Felix Petriconi

Version 1.0 of a new C++ future and channel library has been released.

There Is A New Future

by Sean Parent, Foster Brereton and Felix Petriconi

About the library:

This library provides high level abstractions for implementing algorithms that eases the use of multiple CPU cores while minimizing the contention.

The future implementaton differs in several aspects compared to the C++11/14/17 standard futures: It provides continuations and joins, which were just added in a C++17 TS. But more important this futures propagate values through the graph and not futures. This allows an easy way of creating splits. That means a single future can have multiple continuations into different directions. An other important difference is that the futures support cancellation. So if one is not anymore interested in the result of a future, then one can destroy the future without the need to wait until the future is fullfilled, as it is the case with std::future (and boost::future). An already started future will run until its end, but will not trigger any continuation. So in all these cases, all chained continuations will never be triggered. Additionally the future interface is designed in a way, that one can use build in or custom build executors.

Since one can create with futures only graphs for single use, this library provides as well channels. With these channels one can build graphs, that can be used for multiple invocations.

Serializing access to Streams -- Marco Foco

A new blog post containing runnable code from the Italian C++ Community:

Serializing access to Streams

by Marco Foco

From the article:

Two or more threads were writing to cout using the form:

cout << someData << "some string" << someObject << endl;

And one of the problems was that data sent from one thread often interrupted another thread, so the output was always messed up. [...] I started designing a solution by giving myself some guidelines, here listed in order of importance...

Range comprehensions with C++ lazy generators -- Paolo Severini

From a totally unnecessary blog (we beg to differ):

Range comprehensions with C++ lazy generators

by Paolo Severini

From the article:

Lazy evaluation is a powerful tool and a pillar of functional programming; it gives the ability to construct potentially infinite data structures, and increases the performance by avoiding needless calculations ...

... Functional languages like Haskell have the concept of list comprehensions ... In C#, of course, we have LINQ ... It would be nice to have something similar in an eager language like C++ ... now the lazy, resumable generators proposed by N4286 seem perfect for this purpose ... We can use the VS2015 CTP prototype to experiment with this idea ...

Lock-Free Data Structures. The Evolution of a Stack -- Max Khiszinsky

Max Khiszinsky describes in his recent blog article different approaches to develop concurrent containers.

Lock-Free Data Structures. The Evolution of a Stack

by Max Khiszinsky

From the article

Describing the known algorithms would be quite boring, as there would be a lot of [pseudo-]code, plenty of details that are important but quite specific. After all, you can always find them in the references I provide in articles. What I wanted was to tell you an interesting story about exciting things. I wanted to show the development of approaches to designing concurrent containers.

C++ SIMD parallelism with Intel Cilk Plus and OpenMP 4.0

A new video from Meeting C++ 2014

C++ SIMD parallelism with Intel Cilk Plus and OpenMP 4.0

by Georg Zitzlsberger

From the talk description:

Performance is one of the most important aspects that comes to mind if deciding for a programming language. Utilizing performance of modern processors is not as straight forward as it has been decades ago. Modern processors only rarely improve serial execution of applications by increasing their frequency or adding more execution units.