[Cbc] Meaning of number of nodes (getNodeCount())

[Kish Shen]

Hi,

I have been looking at terminating the MIP search for Cbc with setting 
of CbcMaxNumNode, and I am not sure I understand how the number of node 
is calculated:

I tried setting CbcMaxNumNode on solving a version of the bell3a 
problem, using CbcSolver. On a normal run of the solve, I used 
getNodeCount() returned 15532, which I assumed is the number of nodes 
(linear solves) performed for the complete MIP.

I then reran the problem, setting CbcMaxNumNode to 2500. However, this 
did not terminate the MIP early, and the problem appears to be solved to 
completion, again with 15532 nodes.

I then noticed that in the message printing, I only saw one status 
message of the form:

"After 1000 nodes, ....."

so it seems that the search finished before 2000 nodes was reached 
(because I didn't see a message "After 2000 nodes...."), and yet 
getNodeCount() is substantially larger than 2000.

When I set CbcMaxNumNode to 200, the MIP search did terminate early at 
200 nodes.

This seems to suggest that some extra number is added to the node count 
when the MIP is finished -- does anyone know what the extra node count 
is for?

Thanks in advance for any information/help!

Cheers,

Kish

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