[parsec-users] Segmentation Fault for freqmine

Saugata Ghose sg532 at cornell.edu
Fri Jan 16 14:43:44 EST 2009


I compiled the serial versions of the benchmarks, and ran into a  
problem with the freqmine benchmark.  I was wondering if anyone else  
had encountered it.  On one of my machines, everything compiled fine,  
and the test ran successfully.  However, on the second machine, I  
compiled and executed the test, and freqmine would produce a seg fault.

I traced this back to the global thread_mapfile variable in  
fp_tree.cpp.  It turns out that when sort is first called, for some  
strange reason, it nulls the thread_mapfile pointer, which in turn  
produces a segmentation fault when the pointer is read next.  The  
nulling seems to happen at the moment sort is called.  If I insert a  
dummy MapFile ** pointer right after thread_mapfile's declaration, the  
program executes fine and produces identical outputs to the run on the  
machine that did not seg fault.

Has anyone else experienced something similar?  Is there a workaround  
for this?  My suspicion is that the sumntype array is hitting a  
negative index access (indicating incorrect program behavior), but it  
seems odd that this doesn't affect the other build that I have.

Thanks,
-Saugata


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