[SCIP] FiberSCIP is very slow in deterministic mode

[Vladimir V. Voloshinov]

Dear SCIP team,
we have been successfully using SCIP & FiberSCIP & ParaSCIP for a long time.
But sometimes some problems arise...
Recently we found that FiberSCIP works very very slowly in deterministic
mode.
Moreover, it looks like *Deterministic=TRUE* (in ug.set file) switches off
multithreading and regardless of *-sth* setting total CPU load becomes the
same as for the case *-sth=1*.
But performance becomes even worse than for one threaded SCIP... See
example below.

The question is: maybe there are some other ways to get a deterministic
behaviour of FiberSCIP keeping performance? The question arose when we
tried to compare FiberSCIP performance and results on different computing
environments...

Below is an example of results for some NLP global optimization problem
without discrete variables but with SOS2 constraints:
___________________________________________________________
Presolved Problem  :
  Variables       : 145 (0 binary, 0 integer, 0 implicit integer, 145
continuous)
  Constraints    : 61
Constraints      : Number
  SOS2             : 15
  linear              : 30
  nonlinear        : 16
--------------------------------------------------------------------------------------------------
It was solved with total 10% gap, *-sth=16* and *Deterministic=FALSE* in 87
sec:
_____________________________________________________
SCIP Status        : solving was interrupted [given gap reached]
Total Time         : 86.80
B&B Tree           :   nodes (total)    : 202112
Solution           :
  Primal Bound     : +3.10185241045302e-03
  Dual Bound       : +2.98514588645749e-03
Gap                : 3.90958 %
----------------------------------------------------------------------------------------

But solving time with the same settings and *Deterministic=TRUE* became
almost 50 times bigger:
_____________________________________________________
SCIP Status        : solving was interrupted [given gap reached]
Total Time         : 4216.07
B&B Tree           :   nodes (total)    : 141474
Solution           :
  Primal Bound     : +3.09812857597093e-03
  Dual Bound       : +2.98180690970866e-03
Gap                : 3.90105 %
----------------------------------------------------------------------------------------

Sincerely yours,
Vladimir V. Voloshinov,
web: GoogleScholar profile
<https://scholar.google.ru/citations?hl=en&user=-m4QhNEAAAAJ&view_op=list_works&sortby=pubdate>
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