[SCIP] Difficulty in restarting B&B; SCIPreleaseVar Assertion failed with my constraint handler

[Dev Anand]

Dear Scipers,

I am new to SCIP. I am trying to implement my own brancher in scip. My
brancher requires storing some relevant information at each branching node.
The FAQ provided in SCIP documentation guided me to create a
constraint_handler for this. As mentioned I took the help of constraint
handler of the coloring problem
(examples/Coloring/src/cons_storeGraph.c)).  To get the data stored in a
constraint, I have written external methods to my constraint handler.
The brancher works fine and my constraint handler helps in storing and
fetching the relevant data at each branching node. But, when the branch
restarts I get the error message just after the solver calls
SCIPsetExitsolPlugins.
The message I get is:
SCIPreleaseVar: Assertion `(*var)->scip == scip' failed.

When I debugged, I found that after executing SCIP_DECL_CONSEXITSOL and
SCIP_DECL_CONSDELETE in my constraint handle without any error, it stuck on
SCIPsepaExitsol in deinitialization method of *clique* *separator.*
When I further looked into it, the tcliquegraphFree in sepa_clique.c, calls
the method SCIPreleaseVar. And surprisingly the first variable itself, when
I check (*var)->scip = 0x0, failed with  Assertion `(*var)->scip == scip'
failed.

Currently, I am only adding one constraint to my constraint handler when
the B&B process is about to begin (in the method SCIP_DECL_CONSINITSOL).
So, I am not using SCIP_DECL_CONSACTIVE and SCIP_DECL_CONSDEACTIVE methods.
I use my external methods to fetch and store the consdata information.

I would like to know how my constraint handle is linked with the tclique
separator. I am finding difficulty in resolving this issue. Please help me
to resolve it.

Regards,
Devanand
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