From db549777e27b8ff7196fea50f441cd84a5debc39 Mon Sep 17 00:00:00 2001
From: Matthias Miltenberger <matthias.miltenberger@gmail.com>
Date: Sat, 30 Oct 2021 13:39:36 +0200
Subject: [PATCH 1/2] fix concurrent solve test

---
 tests/test_lp_concurrent.py | 25 -------------------------
 tests/test_model.py         | 13 +++++++++++++
 2 files changed, 13 insertions(+), 25 deletions(-)
 delete mode 100644 tests/test_lp_concurrent.py

diff --git a/tests/test_lp_concurrent.py b/tests/test_lp_concurrent.py
deleted file mode 100644
index 42004f473..000000000
--- a/tests/test_lp_concurrent.py
+++ /dev/null
@@ -1,25 +0,0 @@
-from pyscipopt import LP
-
-def test_lp():
-    # create LP instance, minimizing by default
-    myLP = LP()
-
-    # create cols w/o coefficients, 0 objective coefficient and 0,\infty bounds
-    myLP.addCols(2 * [[]])
-
-    # create rows
-    myLP.addRow(entries = [(0,1),(1,2)] ,lhs = 5)
-    lhs, rhs = myLP.getSides()
-    assert lhs[0] == 5.0
-    assert rhs[0] == myLP.infinity()
-
-    assert(myLP.ncols() == 2)
-    myLP.chgObj(0, 1.0)
-    myLP.chgObj(1, 4.0)
-
-    solval = myLP.solveConcurrent()
-
-    assert round(5.0 == solval)
-
-if __name__ == "__main__":
-    test_lp()
diff --git a/tests/test_model.py b/tests/test_model.py
index 0eaf655b8..f86fac33b 100644
--- a/tests/test_model.py
+++ b/tests/test_model.py
@@ -78,6 +78,15 @@ def test_model():
 
     assert s.getStatus() == 'unbounded'
 
+def test_solve_concurrent():
+    s = Model()
+    x = s.addVar("x", vtype = 'C', obj = 1.0)
+    y = s.addVar("y", vtype = 'C', obj = 2.0)
+    c = s.addCons(x + y <= 10.0)
+    s.setMaximize()
+    s.solveConcurrent()
+    assert s.getStatus() == 'optimal'
+    assert s.getObjVal() == 20.0
 
 def test_multiple_cons_simple():
     def assert_conss_eq(a, b):
@@ -177,4 +186,8 @@ def test_model_ptr():
 
 if __name__ == "__main__":
     test_model()
+    test_solve_concurrent()
+    test_multiple_cons_simple()
+    test_multiple_cons_names()
+    test_multiple_cons_params()
     test_model_ptr()

From 62445e65178550eec222a2b585f232c6a80e749f Mon Sep 17 00:00:00 2001
From: Matthias Miltenberger <matthias.miltenberger@gmail.com>
Date: Sat, 30 Oct 2021 14:02:01 +0200
Subject: [PATCH 2/2] add check for available TPI for concurrent solve

---
 src/pyscipopt/scip.pxd | 3 +++
 src/pyscipopt/scip.pyx | 8 ++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/pyscipopt/scip.pxd b/src/pyscipopt/scip.pxd
index 8e39c1a82..d2bfbfdfe 100644
--- a/src/pyscipopt/scip.pxd
+++ b/src/pyscipopt/scip.pxd
@@ -1681,6 +1681,9 @@ cdef extern from "scip/scip_tree.h":
 cdef extern from "scip/scip_var.h":
     SCIP_RETCODE SCIPchgVarBranchPriority(SCIP* scip, SCIP_VAR* var, int branchpriority)
 
+cdef extern from "tpi/tpi.h":
+    int SCIPtpiGetNumThreads()
+
 cdef class Expr:
     cdef public terms
 
diff --git a/src/pyscipopt/scip.pyx b/src/pyscipopt/scip.pyx
index 17da39408..78ad7d24f 100644
--- a/src/pyscipopt/scip.pyx
+++ b/src/pyscipopt/scip.pyx
@@ -3096,8 +3096,12 @@ cdef class Model:
     def solveConcurrent(self):
         """Transforms, presolves, and solves problem using additional solvers which emphasize on
         finding solutions."""
-        PY_SCIP_CALL(SCIPsolveConcurrent(self._scip))
-        self._bestSol = Solution.create(self._scip, SCIPgetBestSol(self._scip))
+        if SCIPtpiGetNumThreads() == 1:
+            warnings.warn("SCIP was compiled without task processing interface. Parallel solve not possible - using optimize() instead of solveConcurrent()") 
+            self.optimize()
+        else:
+            PY_SCIP_CALL(SCIPsolveConcurrent(self._scip))
+            self._bestSol = Solution.create(self._scip, SCIPgetBestSol(self._scip))
 
     def presolve(self):
         """Presolve the problem."""