Merge branch 'master' into expr/__mul__

Author: Joao-Dionisio

CHANGELOG.md

@@ -2,10 +2,14 @@
 
 ## Unreleased
 ### Added
+- Added `getMemUsed()`, `getMemTotal()`, and `getMemExternEstim()` methods
 ### Fixed
+- Removed `Py_INCREF`/`Py_DECREF` on `Model` in `catchEvent`/`dropEvent` that caused memory leak for imbalanced usage
+- Used getIndex() instead of ptr() for sorting nonlinear expression terms to avoid nondeterministic behavior 
 ### Changed
 - Speed up `constant * Expr` via C-level API
 ### Removed
+- Removed outdated warning about Make build system incompatibility
 
 ## 6.1.0 - 2026.01.31
 ### Added

INSTALL.md

@@ -18,10 +18,6 @@ Suite](https://www.scipopt.org/). Please, make sure that your SCIP installation
 
 **Note that the latest PySCIPOpt version is usually only compatible with the latest major release of the SCIP Optimization Suite. See the table on the README.md page for details.**
 
-If you install SCIP yourself and are not using the installer packages, you need to [install the
-SCIP Optimization Suite using CMake](https://www.scipopt.org/doc/html/md_INSTALL.php#CMAKE).
-The Makefile system is not compatible with PySCIPOpt!
-
 If installing SCIP from source or using PyPI with a python and operating system that is not mentioned above, and SCIP is not installed in the global path,
 you need to specify the install location using the environment variable
 `SCIPOPTDIR`:

docs/build.rst

@@ -44,10 +44,6 @@ To download SCIP please either use the pre-built SCIP Optimization Suite availab
     * - 3.2
       - 1.0
 
-.. note:: If you install SCIP yourself and are not using the pre-built packages,
-  you need to install the SCIP Optimization Suite using CMake.
-  The Makefile system is not compatible with PySCIPOpt!
-
 Download Source Code
 ======================
 

src/pyscipopt/expr.pxi

@@ -108,7 +108,7 @@ cdef class Term:
     cdef Py_ssize_t hashval
 
     def __init__(self, *vartuple: Variable):
-        self.vartuple = tuple(sorted(vartuple, key=lambda v: v.ptr()))
+        self.vartuple = tuple(sorted(vartuple, key=lambda v: v.getIndex()))
         self.ptrtuple = tuple(v.ptr() for v in self.vartuple)
         self.hashval = <Py_ssize_t>hash(self.ptrtuple)
 
@@ -138,7 +138,7 @@ cdef class Term:
         while i < n1 and j < n2:
             var1 = <Variable>PyTuple_GET_ITEM(self.vartuple, i)
             var2 = <Variable>PyTuple_GET_ITEM(other.vartuple, j)
-            if var1.ptr() <= var2.ptr():
+            if var1.getIndex() <= var2.getIndex():
                 vartuple[k] = var1
                 i += 1
             else:

src/pyscipopt/scip.pxd

@@ -1822,6 +1822,11 @@ cdef extern from "blockmemshell/memory.h":
     void BMScheckEmptyMemory()
     long long BMSgetMemoryUsed()
 
+cdef extern from "scip/scip_mem.h":
+    SCIP_Longint SCIPgetMemUsed(SCIP* scip)
+    SCIP_Longint SCIPgetMemTotal(SCIP* scip)
+    SCIP_Longint SCIPgetMemExternEstim(SCIP* scip)
+
 cdef extern from "scip/scip_expr.h":
     SCIP_RETCODE SCIPcreateExpr(SCIP* scip,
                                 SCIP_EXPR** expr,

src/pyscipopt/scip.pxi

@@ -11268,7 +11268,6 @@ cdef class Model:
         else:
             raise Warning("event handler not found")
 
-        Py_INCREF(self)
         PY_SCIP_CALL(SCIPcatchEvent(self._scip, eventtype, _eventhdlr, NULL, NULL))
 
     def dropEvent(self, eventtype, Eventhdlr eventhdlr):
@@ -11288,7 +11287,6 @@ cdef class Model:
         else:
             raise Warning("event handler not found")
 
-        Py_DECREF(self)
         PY_SCIP_CALL(SCIPdropEvent(self._scip, eventtype, _eventhdlr, NULL, -1))
 
     def catchVarEvent(self, Variable var, eventtype, Eventhdlr eventhdlr):
@@ -11467,6 +11465,41 @@ cdef class Model:
 
         locale.setlocale(locale.LC_NUMERIC,user_locale)
 
+    def getMemUsed(self):
+        """
+        Gets the total number of bytes used in block and buffer memory.
+
+        Returns
+        -------
+        int
+
+        """
+        return SCIPgetMemUsed(self._scip)
+
+    def getMemTotal(self):
+        """
+        Gets the total number of bytes in block and buffer memory
+        (i.e., total allocated, including unused).
+
+        Returns
+        -------
+        int
+
+        """
+        return SCIPgetMemTotal(self._scip)
+
+    def getMemExternEstim(self):
+        """
+        Gets the estimated number of bytes used by external software,
+        e.g., the LP solver.
+
+        Returns
+        -------
+        int
+
+        """
+        return SCIPgetMemExternEstim(self._scip)
+
     def getNLPs(self):
         """
         Gets total number of LPs solved so far.

src/pyscipopt/scip.pyi

@@ -1153,6 +1153,9 @@ class Model:
     def getNLPIterations(self) -> Incomplete: ...
     def getNLPRows(self) -> Incomplete: ...
     def getNLPs(self) -> Incomplete: ...
+    def getMemUsed(self) -> int: ...
+    def getMemTotal(self) -> int: ...
+    def getMemExternEstim(self) -> int: ...
     def getNLeaves(self) -> Incomplete: ...
     def getNLimSolsFound(self) -> Incomplete: ...
     def getNNlRows(self) -> Incomplete: ...

tests/test_event.py

@@ -1,4 +1,4 @@
-import pytest, random
+import pytest, weakref, gc, random
 
 from pyscipopt import Model, Eventhdlr, SCIP_RESULT, SCIP_EVENTTYPE, SCIP_PARAMSETTING, quicksum
 
@@ -189,4 +189,42 @@ def eventexec(self, event):
     m.includeEventhdlr(ev, "var_event", "event handler for var events")
 
     with pytest.raises(Exception):
-        m.optimize()
+        m.optimize()
+
+def test_catchEvent_does_not_leak_model():
+    """catchEvent should not artificially increment the Model's reference count.
+
+    Previously, catchEvent called Py_INCREF(self) on the Model, and dropEvent
+    called Py_DECREF(self). In practice these calls are often unbalanced — event
+    handlers commonly catch events without a matching drop (e.g. calling
+    catchEvent in eventinit but omitting dropEvent in eventexit). Each unmatched
+    catchEvent permanently inflated the Model's refcount, preventing garbage
+    collection.
+    """
+
+    class SimpleEvent(Eventhdlr):
+        def eventinit(self):
+            self.model.catchEvent(SCIP_EVENTTYPE.NODEFOCUSED, self)
+
+        def eventexit(self):
+            pass  # intentionally no dropEvent, which is bad practice
+
+        def eventexec(self, event):
+            pass
+
+    m = Model()
+    m.hideOutput()
+    ev = SimpleEvent()
+    m.includeEventhdlr(ev, "simple", "test event handler")
+    m.addVar("x", obj=1, vtype="I")
+    m.optimize()
+
+    ref = weakref.ref(m)
+
+    del ev
+    gc.collect()
+    assert ref() is not None, "Model was garbage collected — event handler absorbed a reference"
+
+    del m
+    gc.collect()
+    assert ref() is None, "Model was not garbage collected — catchEvent likely leaked a reference"

tests/test_model.py

@@ -642,3 +642,23 @@ def test_getSolVal():
         m.getVal("not_a_var")
     with pytest.raises(TypeError):
         m.getSolVal(sol, "not_a_var")
+
+
+def test_memory_methods():
+    m = Model()
+
+    # Memory values should be non-negative even on an empty model
+    assert m.getMemUsed() >= 0
+    assert m.getMemTotal() >= 0
+    assert m.getMemExternEstim() >= 0
+
+    # Total allocated should be at least as much as actively used
+    assert m.getMemTotal() >= m.getMemUsed()
+
+    # After adding variables and solving, memory usage should increase
+    x = m.addVar("x", vtype="C", obj=1.0)
+    m.addCons(x >= 0)
+    m.optimize()
+
+    assert m.getMemUsed() > 0
+    assert m.getMemTotal() > 0