Error in Connected Components Result

[Lau Yang Hao <lauyh@…>]

I've been using the connected components function from the parallel Boost graph library. The function has helped my coding and I'm grateful to the authors. I have tested the function on various graphs and verified its results. However, in one test case, the function leaves a vertex out of its rightful component when running with 16 processes. The problem does not occur when running with fewer processes. As the graph where the problem occurs is complicated, I would be unreasonable to ask for too much help in resolving the problem. However, any pointers would be greatly appreciated.

In the attached code, I build and run the connected components function on a graph. I build the graph from 16 attached files numbered 'a' to 'p'. The i-th file contains the number and owner-local pairs of adjacent vertices of consecutive vertices to be stored on the i-th process. After adding the vertices and edges between them, I first verify there is an edge between the problem vertex (0,20) and another vertex, then run the connected components function. Then printing the parent of problem vertex and its children shows the vertex is in a separate component from its neighbor.

It would be great if you could look over the code and point out any obvious errors. Thank you!

[Lau Yang Hao <lauyh@…>]

source and input files