When I connect to IBM MQ QueueManager using multi-threading, it does not connect all of the requests to MQ. Few connect and few fail. If I use thread count as 1 then all the request are connected. When I increase thread count to 2 or 3 then few will success and few will fail.

When I connect without UserId and Password, multithreading is working properly.

public class AML_MQIntegration : IDisposable
{
    #region Decalrations
    MQQueue objMQQueue;
    MQMessage objPutMQMessage;
    MQMessage objReadMQMessage;
    MQQueueManager objMQQueueManager;

    public AML_MQIntegration()
    {
       
                    Hashtable properties = new Hashtable();
                    properties.Add(MQC.TRANSPORT_PROPERTY, MQC.TRANSPORT_MQSERIES_MANAGED);
                    properties.Add(MQC.HOST_NAME_PROPERTY, Common.FTS_MQ_HostName);
                    properties.Add(MQC.CHANNEL_PROPERTY, Common.QUEUE_CHANNEL);
                    properties.Add(MQC.PORT_PROPERTY, Common.FTS_MQ_Port);

                    properties.Add(MQC.USER_ID_PROPERTY, Common.FTS_MQ_UserId);
                    properties.Add(MQC.PASSWORD_PROPERTY, Common.FTS_MQ_Password);

                    properties.Add(MQC.USE_MQCSP_AUTHENTICATION_PROPERTY, true);

                    Common.WriteFTSLog("HOST_NAME_PROPERTY " + Common.FTS_MQ_HostName + Environment.NewLine);
                    Common.WriteFTSLog("CHANNEL_PROPERTY " + Common.QUEUE_CHANNEL + Environment.NewLine);
                    Common.WriteFTSLog("PORT_PROPERTY " + Common.FTS_MQ_Port + Environment.NewLine);
                   
                    objMQQueueManager = new MQQueueManager(Common.QUEUEMANAGER_NAME, properties);                                               
               
    }

    public string PutMessageOnQueue_Inward(string message, string strMessageID)
    {

        //bool isSuccess = true;
        string writeQueueName = Common.WRITE_MESSAGE_QUEUENAME_INWARD;
        try
        {
            objMQQueue = objMQQueueManager.AccessQueue(writeQueueName, MQC.MQOO_OUTPUT + MQC.MQOO_FAIL_IF_QUIESCING);

            objPutMQMessage = new MQMessage();

            //UTF-8 character encoding
            objPutMQMessage.CharacterSet = 1208;
            objPutMQMessage.WriteString(message);

            objPutMQMessage.Format = MQC.MQFMT_STRING;
            objPutMQMessage.MessageType = MQC.MQMT_DATAGRAM;
            objPutMQMessage.Report = MQC.MQRO_NONE;

            objMQQueue.Put(objPutMQMessage);
            objMQQueueManager.Commit();


            if (objMQQueue.OpenStatus)
            {
                objMQQueue.Close();
            }
        }
        catch (Exception ex)
        {
            //LogMQ("Error while putting message in to MQ ," + ex.Message + " " + ex.StackTrace, "MQ_Error_");
            Common.WriteFTSLog("Exception for PutMessageOnQueue_Inward strMessageID:" + strMessageID + Environment.NewLine + ex.Message + ex.StackTrace);
            //isSuccess = false;
            message = null;
        }

        finally
        {
            objMQQueue.Close();
            objMQQueueManager.Disconnect();
        }
        //return isSuccess;

        return message;
    }
    }

    public void ProcessInwardInstCovAMLRequestSendProcess(AMLRequestDetails AmlRequestDetail)
    {
        DAL_InwardAMLProcess objDAL_AMLDetails = new DAL_InwardAMLProcess();
        string Error = string.Empty;

        using (AML_MQIntegration objMQIntegration = new AML_MQIntegration())
        {
            try
            {                   
                if (!string.IsNullOrEmpty(AmlRequestDetail.Request))
                {                       
                    string XMLSend = objMQIntegration.PutMessageOnQueue_Inward(AmlRequestDetail.Request, AmlRequestDetail.AmlSRQId.ToString());

                    if (!string.IsNullOrEmpty(XMLSend))
                    {
                        if (objDAL_AMLDetails.UpdateAMLScreeningRequestInstCov(AmlRequestDetail.AmlSRQId, "U", ref Error))
                            Common.WriteFTSLog("Successfully Saved Inward AML Request Send status for Inward AML Request Id: " + AmlRequestDetail.AmlSRQId);
                        else
                            Common.WriteFTSLog("Failed Saving Inward AML Request Send status for Inward AML Request Id: " + AmlRequestDetail.AmlSRQId);
                    }
                    else
                    {
                        Common.WriteFTSLog("Failed during Request Send for Inward AML Request Id: " + AmlRequestDetail.AmlSRQId);
                        objDAL_AMLDetails.UpdateAMLScreeningRequestInstCov(AmlRequestDetail.AmlSRQId, "E", ref Error);
                    }
                }
            }
            catch (Exception ex)
            {
                Common.WriteFTSLog("Exception occured during Request Send for Inward AML Request Id: " + AmlRequestDetail.AmlSRQId + " " + ex.Message.ToString() + ex.StackTrace);
                objDAL_AMLDetails.UpdateAMLScreeningRequestInstCov(AmlRequestDetail.AmlSRQId, "E", ref Error);
                Common.handleErrorLogInService(ex);
            }
        }
    }