<font size=2 face="sans-serif">We are seeing a segfault from Cbc when
both multi-threading and equal-cost variable aggregation are enabled. The
segfault occurs right after Cbc works through its root cuts. The
Cbc version is the trunk build of March 20; it's not stable because Dr.
Forrest had just added equal-cost variable aggregation.</font>
<br>
<br><font size=2 face="sans-serif">Here is a log of Cbc output. I
can supply an MPS model, but it's the same one I sent to Dr. Forrest in
March.</font>
<br>
<br><font size=2 face="sans-serif">bin/cbc ../last-problem.mps -extrav
8 -threads 104 -solve</font><font size=3> </font><font size=2 face="sans-serif"><br>
Welcome to the CBC MILP Solver <br>
Version: Trunk (unstable) <br>
Build Date: Mar 20 2013 <br>
Revision Number: 1876 </font><font size=3><br>
</font><font size=2 face="sans-serif"><br>
command line - bin/cbc ../last-problem.mps -extrav 8 -threads 104 -solve
(default strategy 1)</font><font size=3> </font><font size=2 face="sans-serif"><br>
At line 1 NAME BLANK</font><font size=3>
</font><font size=2 face="sans-serif"><br>
At line 2 ROWS</font><font size=3> </font><font size=2 face="sans-serif"><br>
At line 1694 COLUMNS</font><font size=3> </font><font size=2 face="sans-serif"><br>
At line 7264 RHS</font><font size=3> </font><font size=2 face="sans-serif"><br>
At line 7664 BOUNDS</font><font size=3> </font><font size=2 face="sans-serif"><br>
At line 7883 ENDATA</font><font size=3> </font><font size=2 face="sans-serif"><br>
Problem BLANK has 1690 rows, 218 columns and 10834 elements</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Coin0008I BLANK read with 0 errors</font><font size=3> </font><font size=2 face="sans-serif"><br>
extraVariables was changed from 0 to 8</font><font size=3> </font><font size=2 face="sans-serif"><br>
threads was changed from 0 to 104</font><font size=3> </font><font size=2 face="sans-serif"><br>
Continuous objective value is 496912 - 0.01 seconds</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Cgl0003I 0 fixed, 35 tightened bounds, 2 strengthened rows, 0 substitutions</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Cgl0004I processed model has 346 rows, 218 columns (218 integer) and 2983
elements</font><font size=3> </font><font size=2 face="sans-serif"><br>
Problem has 218 integers (0 of which binary) and 0 continuous</font><font size=3>
</font><font size=2 face="sans-serif"><br>
218 integer have nonzero objective, 0 have zero objective, 8 different
nonzero (taking abs)</font><font size=3> </font><font size=2 face="sans-serif"><br>
48 variables have objective of 1</font><font size=3> </font><font size=2 face="sans-serif"><br>
1 variables have objective of 4</font><font size=3> </font><font size=2 face="sans-serif"><br>
28 variables have objective of 16.29</font><font size=3> </font><font size=2 face="sans-serif"><br>
28 variables have objective of 31.58</font><font size=3> </font><font size=2 face="sans-serif"><br>
8 variables have objective of 233.333</font><font size=3> </font><font size=2 face="sans-serif"><br>
35 variables have objective of 1235.43</font><font size=3> </font><font size=2 face="sans-serif"><br>
35 variables have objective of 1430.12</font><font size=3> </font><font size=2 face="sans-serif"><br>
35 variables have objective of 2441.3</font><font size=3> </font><font size=2 face="sans-serif"><br>
Replacing model - 7 new variables</font><font size=3> </font><font size=2 face="sans-serif"><br>
Cbc0012I Integer solution of 594089.87 found by DiveCoefficient after 0
iterations and 0 nodes (0.19 seconds)</font><font size=3> </font><font size=2 face="sans-serif"><br>
Cbc0038I Full problem 353 rows 225 columns, reduced to 307 rows 135 columns
- too large</font><font size=3> </font><font size=2 face="sans-serif"><br>
Cbc0031I 11 added rows had average density of 185.27273</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Cbc0013I At root node, 11 cuts changed objective from 497140.24 to 499066.93
in 100 passes</font><font size=3> </font><font size=2 face="sans-serif"><br>
Cbc0014I Cut generator 0 (Probing) - 0 row cuts average 0.0 elements, 4
column cuts (4 active) in 0.768 seconds - new frequency is 1</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Cbc0014I Cut generator 1 (Gomory) - 1621 row cuts average 213.4 elements,
0 column cuts (11 active) in 0.561 seconds - new frequency is 1</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Cbc0014I Cut generator 2 (Knapsack) - 0 row cuts average 0.0 elements,
0 column cuts (0 active) in 0.045 seconds - new frequency is -100</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Cbc0014I Cut generator 3 (Clique) - 0 row cuts average 0.0 elements, 0
column cuts (0 active) in 0.001 seconds - new frequency is -100</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Cbc0014I Cut generator 4 (MixedIntegerRounding2) - 0 row cuts average 0.0
elements, 0 column cuts (0 active) in 0.106 seconds - new frequency
is -100</font><font size=3> </font><font size=2 face="sans-serif"><br>
Cbc0014I Cut generator 5 (FlowCover) - 0 row cuts average 0.0 elements,
0 column cuts (0 active) in 0.235 seconds - new frequency is -100</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Cbc0014I Cut generator 6 (TwoMirCuts) - 225 row cuts average 165.6 elements,
0 column cuts (0 active) in 0.143 seconds - new frequency is -100</font><font size=3>
</font><font size=2 face="sans-serif"><br>
Segmentation fault (core dumped)</font>
<br>