Dispose of ctypes to fix np.array holding on to memory for too long (fixes #108) (#109)

rstarkov · web-flow · commit 25a5c0849ff2 · 2022-12-04T22:40:50.000+01:00
* Dispose of ctypes to fix np.array holding on to memory for too long (fixes #108) * Unit test for np.array memory disposal * Dispose of temporary array in the other path through np.array
diff --git a/src/Numpy/Manual/np.array.cs b/src/Numpy/Manual/np.array.cs
@@ -42,6 +42,7 @@ public static NDarray array(NDarray @object, Dtype dtype = null, bool? copy = nu
             if (subok != null) kwargs["subok"] = ToPython(subok);
             if (ndmin != null) kwargs["ndmin"] = ToPython(ndmin);
             dynamic py = self.InvokeMethod("array", args, kwargs);
+            args.Dispose();
             return ToCsharp<NDarray>(py);
         }
 
@@ -52,7 +53,8 @@ public static NDarray<T> array<T>(T[] @object, Dtype dtype = null, bool? copy =
             var ndarray = np.empty(new Shape(@object.Length), dtype: type, order: order); 
             if (@object.Length == 0)
                 return new NDarray<T>(ndarray);
-            long ptr = ndarray.PyObject.ctypes.data;
+            var ctypes = ndarray.PyObject.ctypes;
+            long ptr = ctypes.data;
             switch ((object)@object)
             {
                 case char[] a: Marshal.Copy(a, 0, new IntPtr(ptr), a.Length); break;
@@ -80,8 +82,13 @@ public static NDarray<T> array<T>(T[] @object, Dtype dtype = null, bool? copy =
                     ndarray.imag = ndimag;
                     break;
             }
-            if (dtype !=null || subok != null || ndmin != null)
-                return new NDarray<T>(np.array(ndarray, dtype:dtype, copy: false, subok: subok, ndmin: ndmin));
+            ctypes.Dispose();
+            if (dtype != null || subok != null || ndmin != null)
+            {
+                var converted = np.array(ndarray, dtype: dtype, copy: false, subok: subok, ndmin: ndmin);
+                ndarray.Dispose();
+                return new NDarray<T>(converted);
+            }
             return new NDarray<T>(ndarray);
         }
 
diff --git a/test/Numpy.UnitTest/NumPy_array_creation.tests.cs b/test/Numpy.UnitTest/NumPy_array_creation.tests.cs
@@ -355,6 +355,43 @@ public void full_likeTest()
 #endif
         }
 
+        [TestMethod]
+        public void arrayLeakTest()
+        {
+            var arr = new double[10_000_000];
+            using (var process = System.Diagnostics.Process.GetCurrentProcess())
+            {
+                long memStart;
+                long getMemAfterGc()
+                {
+                    GC.Collect(2, GCCollectionMode.Forced, true, true);
+                    process.Refresh();
+                    return process.PrivateMemorySize64;
+                }
+                long getOutstandingMem() => getMemAfterGc() - memStart;
+
+                var ones = np.ones(10_000_000); // python runtime warmup
+                ones.Dispose();
+
+                memStart = getMemAfterGc();
+
+                ones = np.ones(10_000_000);
+                Assert.IsTrue(getOutstandingMem() > 70_000_000);
+                ones.Dispose();
+                Assert.IsTrue(getOutstandingMem() < 1_000_000);
+
+                var array = np.array(arr);
+                Assert.IsTrue(getOutstandingMem() > 70_000_000);
+                array.Dispose();
+                Assert.IsTrue(getOutstandingMem() < 1_000_000);
+
+                array = np.array(arr, np.float32);
+                Assert.IsTrue(getOutstandingMem() > 30_000_000);
+                array.Dispose();
+                Assert.IsTrue(getOutstandingMem() < 1_000_000);
+            }
+        }
+
         [TestMethod]
         public void arrayTest()
         {
