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< 		/// A queue with an extra Int32 for keeping track of busy connections.
---
> 		/// Keeps track of available and busy connections.
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< 		private class ConnectorQueue : Queue<NpgsqlConnector>
---
> 		private class ConnectorQueue
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< 			/// The number of pooled Connectors that belong to this queue but
< 			/// are currently in use.
---
> 			/// Connections available to the end user
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< 			public Int32 UseCount = 0;
---
> 			public Queue<NpgsqlConnector> Available = new Queue<NpgsqlConnector>();
> 
> 			/// <summary>
> 			/// Connections currently in use
> 			/// </summary>
> 			public HashSet<NpgsqlConnector> Busy = new HashSet<NpgsqlConnector>();
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< 					if (Queue.Count > 0)
---
> 					if (Queue.Available.Count > 0)
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< 						if (Queue.Count + Queue.UseCount > Queue.MinPoolSize)
---
> 						if (Queue.Available.Count + Queue.Busy.Count > Queue.MinPoolSize)
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< 								Int32 diff = Queue.Count + Queue.UseCount - Queue.MinPoolSize;
---
> 								Int32 diff = Queue.Available.Count + Queue.Busy.Count - Queue.MinPoolSize;
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< 								toBeClosed = Math.Min(toBeClosed, Queue.Count);
---
> 								toBeClosed = Math.Min(toBeClosed, Queue.Available.Count);
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< 									Connector = Queue.Dequeue();
---
> 									Connector = Queue.Available.Dequeue();
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< 			// Fix queue use count. Use count may be dropped below zero if Queue was cleared and there were connections open.
< 			if (Queue.UseCount < 0)
< 			{
< 				Queue.UseCount = 0;
< 			}
< 
< 
< 			if (Queue.Count > 0)
---
> 			if (Queue.Available.Count > 0)
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< 				Connector = Queue.Dequeue();
---
> 				Connector = Queue.Available.Dequeue();
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< 				Queue.UseCount++;
---
> 				Queue.Busy.Add(Connector);
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< 			else if (Queue.Count + Queue.UseCount < Connection.MaxPoolSize)
---
> 			else if (Queue.Available.Count + Queue.Busy.Count < Connection.MaxPoolSize)
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< 				Queue.UseCount++;
---
> 				Queue.Busy.Add(Connector);
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< 				while (Queue.Count + Queue.UseCount < Connection.MinPoolSize)
---
> 				while (Queue.Available.Count + Queue.Busy.Count < Connection.MinPoolSize)
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< 					Queue.Enqueue(Spare);
---
> 					Queue.Available.Enqueue(Spare);
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< 					Queue.UseCount--;
---
> 					Queue.Busy.Remove(Connection.Connector);
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> 				Connector.Close(); // Release connection to postgres
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< 			Queue.UseCount--;
---
> 			bool InQueue = Queue.Busy.Contains(Connector);
> 			Queue.Busy.Remove(Connector);
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< 				Queue.Enqueue(Connector);
---
> 				if (InQueue)
> 					Queue.Available.Enqueue(Connector);
> 				else
> 					Connector.Close();
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< 			while (Queue.Count > 0)
---
> 			while (Queue.Available.Count > 0)
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< 				NpgsqlConnector connector = Queue.Dequeue();
---
> 				NpgsqlConnector connector = Queue.Available.Dequeue();
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> 
> 			// Only connections in busy list will be re-added to pool; connections currently in use should be closed
> 			Queue.Busy.Clear();