Parallel Programming

Since multi-core systems are spreading fast, the problem of parallel programming becomes more and more urgent. However, even the majority of experienced developers are new to this sphere. The existing compilers and code analyzers allow finding some bugs, which appear during parallel code development. However, many errors are not diagnosed. The article contains description of a number of errors, which lead to incorrect behavior of parallel programs created with OpenMP.

The task of familiarizing programmers with the sphere of developing parallel applications is getting more and more urgent. This article is a brief introduction into creation of multi-thread applications based on OpenMP technology. The approaches to debugging and optimization of parallel applications are described.

The article is an introduction into parallel programs for beginners. It was published in "PC World" magazine (http://www.osp.ru/pcworld/2007/10/4623726/).

Testing parallel software is a more complicated task in comparison to testing a standard program. The programmer should be aware both of the traps he can face while testing parallel code and existing methodologies and toolkit.

The article describes a new direction in development of static code analyzers - verification of parallel programs. The article reviews several static analyzers which can claim to be called "Parallel Lint".

As developing parallel software is rather a difficult task at present, the questions of theoretical training of specialists and investigation of methodology of projecting such systems become very urgent. Within the framework of this article we provide historical and technical information preparing a programmer for gaining knowledge in the sphere of developing parallel computer systems.

In the article the question of use of the static code analyzers in modern parallel program development processes is considered. Having appeared in 70-80s as an addition to compilers, the static analyzers stopped to be popular with the developers in 90s. The reason was probably the increase of the errors diagnostics quality by the compilers. But in 2000s the interest to the static code analyzers started to increase again. It is explained by the fact that new static code analyzers were created, which started to detect quite difficult errors in programs. If the static code analyzers of the past made it possible, for example, to detect an uninitialized variable, modern static code analyzers tend to detect an unsafe access to data from several threads. The modern tendency of static code analyzers development became their use for diagnosing errors in parallel programs. In the work the situations are considered, where the use of such tools makes it possible to considerably simplify the process of creating parallel program solutions.

Initially, the article must have been titled "Comparison of diagnostic abilities of PVS-Studio (VivaMP) and Intel C/C++ Compiler ("Parallel Lint")". Absence of sufficient information about "Parallel Lint" restrained the author's abilities and the article turned out to be just a preliminary variant of the comparison. The full variant with correct comparison will be available in future. Pay attention that the article's content is relevant at the time of publishing. Further, diagnostic abilities of the both products can change.

The article briefly describes the OpenMP technology.

The article concerns the problem of excess of program creation terms as a result of a prejudice that programming is simple and even simpler.

The article describes principles on which implementation of the static code analyzer VivaMP is based. The described set of testing logical conditions allows you to diagnose some errors in parallel programs created on the basis of OpenMP technology.

The article briefly concerns methods of estimating the minimum time of executing tasks at optimal distribution of load among processors. The given methods can be used both for homogeneous and heterogeneous computer systems.