Opened 3 years ago

Closed 7 weeks ago

#168 closed defect (migrated)

long postprocessing

Reported by: stefan Owned by: tkr
Priority: major Component: Cbc
Version: 2.9 Keywords:
Cc:

Description

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.

Attachments (3)

cbc.mps.bz2 (16.8 MB) - added by stefan 3 years ago.
instance to reproduce the problem
log520 (14.2 MB) - added by stefan 3 years ago.
logfile
gamslog.bz2 (559.5 KB) - added by stefan 3 years ago.
log from run under GAMS

Change History (5)

Changed 3 years ago by stefan

instance to reproduce the problem

Changed 3 years ago by stefan

logfile

comment:1 Changed 3 years ago by stefan

Originally, we were running this instance from GAMS with a timelimit of 3600s. With GAMS/Cbc, I can also enable the log from Clp. It shows that after the Postprocessing changed objective line, a lot of LP solves happen again, I even see some output about strong branching.

Changed 3 years ago by stefan

log from run under GAMS

comment:2 Changed 7 weeks ago by stefan

  • Resolution set to migrated
  • Status changed from new to closed

This ticket has been migrated to GitHub and will be resolved there: https://github.com/coin-or/Cbc/issues/168

Note: See TracTickets for help on using tickets.