[Cbc-tickets] [COIN-OR Branch-and-Cut MIP Solver] #168: long postprocessing

[COIN-OR Branch-and-Cut MIP Solver]

#168: long postprocessing
-------------------+-----------------
Reporter:  stefan  |      Owner:  tkr
    Type:  defect  |     Status:  new
Priority:  major   |  Component:  Cbc
 Version:  2.9     |   Keywords:
-------------------+-----------------
 If I run the attached instance with a timelimit of 520 seconds, the
 current Cbc stable/2.9 (rev 2279) takes very long in postprocessing.

 That is, there are lines like
 {{{
 Cbc0003I Exiting on maximum nodes
 Cbc0005I Partial search - best objective 1e+50 (best possible -38096162),
 took 10927 iterations and 200 nodes (343.07 seconds)
 ...
 Cbc0005I Partial search - best objective -37399096 (best possible
 -38600836), took 0 iterations and 0 nodes (412.40 seconds)
 }}}
 in the output, but after printing
 {{{
 Cgl0014I Postprocessing changed objective from -37399091 to -37399098 -
 possible tolerance issue - try without preprocessing
 }}}
 it takes very long to terminate.

 Also the final summary indicates that Cbc spend more than an hour for the
 postprocessing, even though it has already almost hit the timelimit before
 that:

 {{{
 Time (CPU seconds):             4559.80
 Time (Wallclock seconds):       4568.20

 Total time (CPU seconds):       4562.79   (Wallclock seconds):
 4571.37
 }}}

 I attach the MPS file and a log from running with -loglevel 4.

--
Ticket URL: <https://projects.coin-or.org/Cbc/ticket/168>
COIN-OR Branch-and-Cut MIP Solver <http://projects.coin-or.org/Cbc>
An LP-based branch-and-cut MIP solver.