ConcurrentQueueSegment allows spinning threads to sleep. (#44265)

* Allow threads to sleep when ConcurrentQueue has many enqueuers/dequeuers. * Update src/libraries/System.Private.CoreLib/src/System/Collections/Concurrent/ConcurrentQueueSegment.cs Co-authored-by: Stephen Toub <[email protected]> * Apply suggestions from code review Co-authored-by: Stephen Toub <[email protected]> Co-authored-by: AMD DAYTONA EPYC <[email protected]> Co-authored-by: Stephen Toub <[email protected]>
dotnet · Nov 5, 2020 · ce4772d · ce4772d
1 parent ae47aa2
commit ce4772d
Showing 1 changed file with 6 additions and 3 deletions.
diff --git a/...raries/System.Private.CoreLib/src/System/Collections/Concurrent/ConcurrentQueueSegment.cs b/...raries/System.Private.CoreLib/src/System/Collections/Concurrent/ConcurrentQueueSegment.cs
@@ -37,6 +37,9 @@ internal sealed class ConcurrentQueueSegment<T>
         internal ConcurrentQueueSegment<T>? _nextSegment; // SOS's ThreadPool command depends on this name
 #pragma warning restore 0649
 
+        /// <summary>Threshold to spin before allowing threads to sleep when there is contention.</summary>
+        private const int Sleep1Threshold = 8;
+
         /// <summary>Creates the segment.</summary>
         /// <param name="boundedLength">
         /// The maximum number of elements the segment can contain.  Must be a power of 2.
@@ -183,7 +186,7 @@ public bool TryDequeue([MaybeNullWhen(false)] out T item)
                 }
 
                 // Lost a race. Spin a bit, then try again.
-                spinner.SpinOnce(sleep1Threshold: -1);
+                spinner.SpinOnce(Sleep1Threshold);
             }
         }
 
@@ -244,7 +247,7 @@ public bool TryPeek([MaybeNullWhen(false)] out T result, bool resultUsed)
                 }
 
                 // Lost a race. Spin a bit, then try again.
-                spinner.SpinOnce(sleep1Threshold: -1);
+                spinner.SpinOnce(Sleep1Threshold);
             }
         }
 
@@ -301,7 +304,7 @@ public bool TryEnqueue(T item)
                 }
 
                 // Lost a race. Spin a bit, then try again.
-                spinner.SpinOnce(sleep1Threshold: -1);
+                spinner.SpinOnce(Sleep1Threshold);
             }
         }