LimitTime => infinite loop

[svigerske]

Issue created by migration from Trac.

Original creator: vejlin

Original creation time: 2011-01-21 13:23:10

For some LimitTime parameter settings the program enters (what appears to be) an infinite loop, printing "Alps0240I" status lines with no progress in lower or upper bounds.

This may be hard to reproduce since it depends on machine speed.

To reproduce:

1. Use the MILPBlock example
2. Use I1_split.mps instance (attached)
3. Use I1_split.block block file (attached)
4. Set LimitTime parameter to something low (so that time expires before the root node has been fully processed, 10 seconds worked for me)
5. run program

This should terminate the program as expected

6. gradually increase LimitTime parameter and run program

At some point you see the infinite loop, for me the program terminated as expected at LimitTime = 60 seconds, but entered the infinite loop at LimitTime settings of 70 seconds and greater. Note that for higher values of LimitTime the program functions normally again. On my computer the interval in which the infinite loop occurs is quite large and difficult to miss.

[svigerske]

Attachment I1_split.mps by vejlin created at 2011-01-21 13:24:36

A reformulated version of the I1 MMKP instance

[svigerske]

Attachment I1_split.block by vejlin created at 2011-01-21 13:25:41

Block file specifying 3 x 0-1 KP and 3 x Multi-Choice KP