[Boost-bugs] [Boost C++ Libraries] #5945: Error in Connected Components Result

Subject: [Boost-bugs] [Boost C++ Libraries] #5945: Error in Connected Components Result
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-09-27 06:16:11

#5945: Error in Connected Components Result
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 Reporter:  Lau Yang Hao <lauyh@…>                   |       Owner:  jewillco
     Type:  Bugs                                     |      Status:  new     
Milestone:  To Be Determined                         |   Component:  graph   
  Version:  Boost 1.47.0                             |    Severity:  Problem 
 Keywords:                                           |  
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 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!

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Ticket URL: <https://svn.boost.org/trac/boost/ticket/5945>
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