[Scip] Assertion fails in RENS heuristic

[Daniel Karch]

Hello everyone,

I just updated from SCIP 2.0.1 to 2.1.0 and unfortunately it introduced
some problems.
Some of them I could work around, they all seem to be triggered by the RENS
heuristic (is it new?).

More precisely, the assertion gets thrown in primal.c:

  time | node  | left  |LP iter|LP it/n| mem |mdpt |frac |vars |cons |cols
|rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap
K13.3s|     1 |     0 |     0 |     - |  12M|   0 |   - | 723 |1372 |   0 |
  0 |   0 |   0 |   0 |      --      | 1.519167e+00 |    Inf
 13.4s|     1 |     0 |   571 |     - |  13M|   0 | 280 | 723 |1372 | 723
|1364 |   0 |   0 |   0 | 8.287500e-01 | 1.519167e+00 |  83.31%
 13.4s|     1 |     0 |   571 |     - |  13M|   0 | 280 | 723 |1372 | 723
|1364 |   0 |   0 |   0 | 8.287500e-01 | 1.519167e+00 |  83.31%
 14.7s|     1 |     0 |   615 |     - |  13M|   0 | 172 | 723 |1372 | 723
|1492 | 128 |   0 |   0 | 8.287500e-01 | 1.519167e+00 |  83.31%
 15.4s|     1 |     0 |   628 |     - |  13M|   0 | 164 | 723 |1372 | 723
|1496 | 132 |   0 |   0 | 8.287500e-01 | 1.519167e+00 |  83.31%
 16.0s|     1 |     0 |   634 |     - |  13M|   0 | 158 | 723 |1372 | 723
|1497 | 133 |   0 |   0 | 8.287500e-01 | 1.519167e+00 |  83.31%
 16.6s|     1 |     0 |   650 |     - |  13M|   0 | 164 | 723 |1372 | 723
|1498 | 134 |   0 |   0 | 8.287500e-01 | 1.519167e+00 |  83.31%
 17.2s|     1 |     0 |   677 |     - |  13M|   0 | 186 | 723 |1372 | 723
|1501 | 137 |   0 |   0 | 8.287500e-01 | 1.519167e+00 |  83.31%
 17.9s|     1 |     0 |   679 |     - |  13M|   0 | 182 | 723 |1372 | 723
|1503 | 139 |   0 |   0 | 8.287500e-01 | 1.519167e+00 |  83.31%
E18.2s|     1 |     0 |  1219 |     - |  13M|   0 | 182 | 723 |1372 | 723
|1503 | 139 |   0 |   0 | 8.287500e-01 | 9.525000e-01 |  14.93%
scipmincon.linux.x86_64.gnu.dbg.cpx: src/scip/primal.c:143: SCIPprimalFree:
Assertion `(*primal)->nexistingsols == 0' failed.

The stack trace is:

#0  0x00002aaaabf9e9d5 in raise () from /lib64/libc.so.6
#1  0x00002aaaabf9fed6 in abort () from /lib64/libc.so.6
#2  0x00002aaaabf97235 in __assert_fail () from /lib64/libc.so.6
#3  0x00000000005c0ec5 in SCIPprimalFree (primal=0x2238fb0,
blkmem=0x1ac8730) at src/scip/primal.c:143
#4  0x00000000005e76ab in freeTransform (scip=0x2238f40) at
src/scip/scip.c:7282
#5  0x00000000005e8fc3 in SCIPfreeTransform (scip=0x2238f40) at
src/scip/scip.c:7744
#6  0x00000000005dc124 in SCIPfreeProb (scip=0x2238f40) at
src/scip/scip.c:4357
#7  0x00000000005ce67f in SCIPfree (scip=0x7fffffffd018) at
src/scip/scip.c:586
#8  0x000000000080c5e3 in SCIPapplyRens (scip=0x1464010, heur=0x1537bd0,
result=0x7fffffffd260, minfixingrate=0.5, minimprove=0.01, maxnodes=5000,
nstallnodes=500, startsol=108 'l', binarybounds=1, uselprows=0) at
src/scip/heur_rens.c:567
#9  0x000000000080cafd in heurExecRens (scip=0x1464010, heur=0x1537bd0,
heurtiming=44, result=0x7fffffffd260) at src/scip/heur_rens.c:695
#10 0x000000000050d36d in SCIPheurExec (heur=0x1537bd0, set=0x14681d0,
primal=0x163fc90, depth=0, lpstateforkdepth=-1, heurtiming=44,
ndelayedheurs=0x7fffffffd25c, result=0x7fffffffd260) at src/scip/heur.c:398
#11 0x0000000000649729 in SCIPprimalHeuristics (set=0x14681d0,
stat=0x156bb20, primal=0x163fc90, tree=0x1774cf0, lp=0x17b0810,
nextnode=0x0, heurtiming=44, foundsol=0x7fffffffd418) at
src/scip/solve.c:241
#12 0x0000000000654e37 in solveNode (blkmem=0x14661b0, set=0x14681d0,
stat=0x156bb20, origprob=0x156c570, transprob=0x1797030, primal=0x163fc90,
tree=0x1774cf0, lp=0x17b0810, relaxation=0x163f710, pricestore=0x186f7d0,
sepastore=0x186f860, branchcand=0x17cc0f0, cutpool=0x186f8e0,
conflict=0x1774ec0, eventfilter=0x16a03c0, eventqueue=0x165bdc0,
cutoff=0x7fffffffd5bc, unbounded=0x7fffffffd5b8, infeasible=0x7fffffffd5b4,
restart=0x7fffffffd748, afternodeheur=0x7fffffffd5ac) at
src/scip/solve.c:3327
#13 0x0000000000657623 in SCIPsolveCIP (blkmem=0x14661b0, set=0x14681d0,
stat=0x156bb20, mem=0x1464120, origprob=0x156c570, transprob=0x1797030,
primal=0x163fc90, tree=0x1774cf0, lp=0x17b0810, relaxation=0x163f710,
pricestore=0x186f7d0, sepastore=0x186f860, cutpool=0x186f8e0,
branchcand=0x17cc0f0, conflict=0x1774ec0, eventfilter=0x16a03c0,
eventqueue=0x165bdc0, restart=0x7fffffffd748) at src/scip/solve.c:3878
#14 0x00000000005e8628 in SCIPsolve (scip=0x1464010) at src/scip/scip.c:7541
#15 0x000000000062dd9b in fromCommandLine (scip=0x1464010,
filename=0x7fffffffe29d "../fsg/polska.fsg") at src/scip/scipshell.c:135
#16 0x000000000062e5cd in SCIPprocessShellArguments (scip=0x1464010,
argc=3, argv=0x7fffffffde38, defaultsetname=0xfd751e "scipmincon.set") at
src/scip/scipshell.c:341
#17 0x00000000004088f4 in runSCIP (argc=3, argv=0x7fffffffde38) at
src/cppmain.cpp:82
#18 0x0000000000408abd in main (argc=3, argv=0x7fffffffde38) at
src/cppmain.cpp:120

This is hard to debug for me, since I can't deduce which part of my code is
responsible for the error, although I suspect that it has to do with the
scip_trans method in my problem data class.

Does anyone know what this error means and how I can prevent it? It occurs
only in debugging.

Thanks in advance,

  Daniel Karch
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