The Art of Debugging with GDB, DDD, and Eclipse

Extended Example

This section presents an example of debugging a shared-memory application developed using OpenMP. The necessary knowledge of OpenMP will be explained below. All that is needed is a basic understanding of threads.

OpenMP Overview

OpenMP is essentially a higher-level parallel programming interface to thread-management operations. The number of threads is set via the environment variable OMP_NUM_THREADS. In the C shell, for instance, you type

% setenv OMP_NUM_THREADS 4

at the shell prompt to arrange to have four threads.

Application code consists of C interspersed with OpenMP directives. Each directive applies to the block that follows it, delimited by left and right braces. The most basic directive is

#pragma omp parallel

This ...