Merge pull request #16295 from stephentoub/cs_random

Delay Random allocation in ConcurrentStack
dotnet · Feb 19, 2017 · c97abfa · c97abfa
2 parents 6d3e8dd + c0a0c55
commit c97abfa
Showing 1 changed file with 13 additions and 2 deletions.
diff --git a/src/System.Collections.Concurrent/src/System/Collections/Concurrent/ConcurrentStack.cs b/src/System.Collections.Concurrent/src/System/Collections/Concurrent/ConcurrentStack.cs
@@ -653,7 +653,7 @@ private int TryPopCore(int count, out Node poppedHead)
             Node head;
             Node next;
             int backoff = 1;
-            Random r = new Random(Environment.TickCount & Int32.MaxValue); // avoid the case where TickCount could return Int32.MinValue
+            Random r = null;
             while (true)
             {
                 head = _head;
@@ -694,7 +694,18 @@ private int TryPopCore(int count, out Node poppedHead)
                     spin.SpinOnce();
                 }
 
-                backoff = spin.NextSpinWillYield ? r.Next(1, BACKOFF_MAX_YIELDS) : backoff * 2;
+                if (spin.NextSpinWillYield)
+                {
+                    if (r == null)
+                    {
+                        r = new Random();
+                    }
+                    backoff = r.Next(1, BACKOFF_MAX_YIELDS);
+                }
+                else
+                {
+                    backoff *= 2;
+                }
             }
         }
 #pragma warning restore 0420