无法从Java DelayQueue中获取项目

Question

我使用DelayQueue存储项目。在某些并发情况下，消费者无法获得任何物品。下面列出了代码示例。任何提示都会有所帮助。

        private void SelfTransferCompleted(IAsyncResult asyncResult)
        {
            Exception exceptionCaught = null;
           // bool exceptionEncountered = true;
            try
            {
                _flow.Call.EndTransfer(asyncResult);
                //Self Transfer has completed. successfully.
                exceptionEncountered = false;
                LogHelper.Log(LogTarget.FileEvent, "IVR Menu Ended self tranfer for call>" +_flow.Call.CallId);
                // cleaning up atten
                string sqlstring = "update astsxqueue set uniqueid ='" + _server.b2bCallDelId + "' where uniqueid='" + _flow.Call.CallId + "';";
                LogHelper.Log(LogTarget.FileEvent, sqlstring);
                _server.mconnector.Mysqlqueryruner(sqlstring);

            }
            catch (OperationTimeoutException orte)
            {
                LogHelper.Log(LogTarget.FileEvent, "IVR SelfTransferCompleted Operation Timeout Exception: " + orte.ToString(), 2);
                exceptionCaught = orte;
                exceptionEncountered = true;
                LogHelper.Log(LogTarget.FileEvent, "IVR SelfTransferCompleted  Trying to transfer to other agent...", 2);
                RetrieveCallAfterTransferFailure();

                LogHelper.Log(LogTarget.FileEvent, "IVR SelfTransferCompleted  Waiting for transfer to complete...");
                _server._waitForTransferComplete.WaitOne();
                LogHelper.Log(LogTarget.FileEvent, "IVR SelfTransferCompleted  Transfer completed.");

            }


            catch (FailureResponseException frte)
            {
                LogHelper.Log(LogTarget.FileEvent, "IVR SelfTransferCompleted  Failure Exception = {0}" + frte.ToString(), 2);
                exceptionCaught = frte;
                exceptionEncountered = true;
                LogHelper.Log(LogTarget.FileEvent, "IVR SelfTransferCompleted  Trying to transfer to other agent...", 2);

                RetrieveCallAfterTransferFailure();
                LogHelper.Log(LogTarget.FileEvent, "Waiting for transfer to complete...");
                _server._waitForTransferComplete.WaitOne();
                LogHelper.Log(LogTarget.FileEvent, "Transfer completed.");

            }

            catch (RealTimeException rte)
            {
                LogHelper.Log(LogTarget.FileEvent, "IVR SelfTransferCompleted  Realtime Exception = {0}" + rte.ToString(),2);
                exceptionCaught = rte;
                exceptionEncountered = true;
                LogHelper.Log(LogTarget.FileEvent, "IVR SelfTransferCompleted  Trying to transfer to other agent...", 2);
                RetrieveCallAfterTransferFailure();
                LogHelper.Log(LogTarget.FileEvent, "IVR Call is retreived waiting a bit...", 2);
                Thread.Sleep(2000);
                LogHelper.Log(LogTarget.FileEvent, "Self Transfer Call flow hold status is :>" + _flow.HoldStatus);

                LogHelper.Log(LogTarget.FileEvent, "IVR Call is retreived time passed...", 2);
                RetrieveCallAfterTransferFailure();
                LogHelper.Log(LogTarget.FileEvent, "Self Transfer Call flow hold status is :>" + _flow.HoldStatus);
                CallAgain();
                // _flow.EndHold(null);

                //   _speechSynthesizer.Speak("We did not get to a green agent. Please retry your option!");  //TEXT TO SPEEECH!
                // SpeakMenuOptions();
                // toneController.ToneReceived += toneController_ToneReceived;
                // Wait for the call to complete the transfer.
                LogHelper.Log(LogTarget.FileEvent, "Waiting for transfer to complete...");
                //_server._waitForTransferComplete.Set();
                LogHelper.Log(LogTarget.FileEvent, "Transfer completed.");

            }

        }