[Mono-bugs] [Bug 70701][Cri] New - use of finalizers causes memory leaks

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Changed by will@cambia.com.

http://bugzilla.ximian.com/show_bug.cgi?id=70701

--- shadow/70701	2004-12-20 15:03:21.000000000 -0500
+++ shadow/70701.tmp.16133	2004-12-20 15:03:21.000000000 -0500
@@ -0,0 +1,93 @@
+Bug#: 70701
+Product: Mono: Runtime
+Version: 1.0
+OS: Red Hat 9.0
+OS Details: Fedora Core 2
+Status: NEW   
+Resolution: 
+Severity: 
+Priority: Critical
+Component: misc
+AssignedTo: mono-bugs@ximian.com                            
+ReportedBy: will@cambia.com               
+QAContact: mono-bugs@ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: use of finalizers causes memory leaks 
+
+Description of Problem:
+
+Certain allocation patterns will cause mono to leak memory.  The 
+determining factors seem to be:
+a) program must allocate a lot of memory fairly quickly
+b) there must be some "big" allocations (50-100k)
+c) some of the objects allocated must have finalizers
+
+This bug makes out product unusable after several hours due to the 
+machine swapping; the example code given here reproduces the same 
+behavior much more quickly.  Both our product and this example are OK 
+under Microsoft's .NET.
+
+Steps to reproduce the problem:
+1. Compile the following program ("mcs MemWorkout.cs"):
+
+using System;
+using System.Collections;
+
+namespace MemWorkout {
+    class MemWorkout {
+        static void Main(string[] args) {
+            ArrayList al = new ArrayList();
+            Random r = new Random(30);
+            DateTime last = DateTime.Now;
+            while (true) {
+                Alloc(al, r);
+
+                DateTime now = DateTime.Now;
+                if (now.Subtract(last).TotalSeconds > 10) {
+                    al.Clear();
+                    last = now;
+                }
+            }
+        }
+
+        static int _cnt = 0;
+
+        static void Alloc(ArrayList save, Random r) {
+            Final f = new Final(r);
+            _cnt++;
+            if (_cnt == 50) {
+                save.Add(f);
+                _cnt = 0;
+            }
+        }
+    }
+
+    class Final {
+        public Final(Random r) {
+            _b = new byte[r.Next(100000)];
+        }
+
+        ~Final() {}
+
+        private byte[] _b;
+    }
+}
+
+2. Run under mono with no command-line arguments
+3. Observe the memory usage over time using top/ps/whatever.
+
+Actual Results:
+
+After 5 minutes or so on my system, mono is using all available system 
+memory.
+
+Expected Results:
+
+Microsoft .NET continues to run the example indefinitely, as does mono if 
+line 39 (~Final() {}) is commented out.
+
+How often does this happen? 
+
+Every time.