Dequeue request in Azure Service Bus when queue length < 10 frequently returns null

Question

I have been experimenting with Azure Service Bus queues in NodeJS. I have built the sender.js and listener.js based on their code sample in the documentation. Building a queue works fine. Dequeuing and deleting messages from the queue works fine until message length reaches 10. At this point, dequeue requests return null messages around 4 out of 5 times. If I keep looping the dequeue requests, eventually, it will dequeue and delete those last 10 messages. But, this seems highly inefficient. Has anyone else experience this problem?

listener.js

var azure = require('azure');
var async = require("async");

var connectionString = process.env.CONNECTION_STRING || "Endpoint=sb://endpoint"; // dev

console.log(process.env.CONNECTION_STRING);

var serviceBusService = azure.createServiceBusService(connectionString);
// var serviceBusService = azure.createServiceBusService();

exports.createQueue = function (req,res) {

    var body = req.body;

    serviceBusService.createQueueIfNotExists(body.queueName, function(error){
        console.log(error);
        if(!error){
            // Queue exists
            return res.send(200);
        } else {
            return res.send(500, error);   
        }
    });
};

exports.sendMessageToQueue = function (req, res) {
    var body = req.body;

    var message = {
        body: 'Test message',
        customProperties: {
            testproperty: 'TestValue'
        }};

    serviceBusService.sendQueueMessage(body.queueName, message, function(error){
        if(!error){
            // message sent
            return res.send(200);
        } else {
            return res.send(500, error);   
        }
    });
}

exports.receiveMessageFromQueue = function (req, res) {
    var body = req.body;

    serviceBusService.receiveQueueMessage(body.queueName, function(error, receivedMessage){
        if(!error){
            console.log(receivedMessage);

            // Message received and deleted
            return res.send(200,receivedMessage);
        }  else {
            return res.send(500, error);   
        }
    });
}

function _receiveMessageFromQueue(queueName,delayTimeIfQueueIsEmpty,callback) {
    serviceBusService.receiveQueueMessage(queueName, function(error, receivedMessage){
        console.log(error, receivedMessage);
        // console.log(error);
        if (error == 'No messages to receive') {
            // call the rest of the code and have it execute after 30 seconds
            setTimeout(function() {
                callback(receivedMessage);
            }, delayTimeIfQueueIsEmpty);
        } else {
            // callback immediately
            callback(receivedMessage);
        }
    });
}

function _sendQueueMessage(queueName,message,callback) {
    serviceBusService.sendQueueMessage(queueName, message, function(error){
        console.log(error);
        callback();
    });
}

function listenMessageQueue(concurrency,delayTimeIfQueueIsEmpty,queueName) {

    var taskHandler = function(task, done) {
        _receiveMessageFromQueue(task.queueName, delayTimeIfQueueIsEmpty, function(message) {
            if (message) {
                console.log('hello ' + message.body);
            }

            myQueue.push({ id: task.id + 1, queueName: queueName, url: "http://localhost/get-person/" + task.id + 1});

            done();
        });
      };

    var queueSize = concurrency;

    var myQueue = async.queue(taskHandler, queueSize);

    myQueue.drain = function() {
        console.log("All the work has been done.");
    }

    for(var i = 0; i < concurrency; i++) {
        myQueue.push({ id: i, queueName: queueName, url: "http://localhost/get-person/"+i });
    }

}

delayTimeIfQueueIsEmpty = 30000; // 30s
concurrency = 2;
queueName = "jobs";
// listen and dequeue message from azure message bus
listenMessageQueue(concurrency,delayTimeIfQueueIsEmpty,queueName);

sender.js

var azure = require('azure');
var async = require("async");

var connectionString = process.env.CONNECTION_STRING || "Endpoint=sb://endpoint";

console.log(process.env.CONNECTION_STRING);

var serviceBusService = azure.createServiceBusService(connectionString);

exports.createQueue = function (req,res) {

    var body = req.body;

    serviceBusService.createQueueIfNotExists(body.queueName, function(error){
        console.log(error);
        if(!error){
            // Queue exists
            return res.send(200);
        } else {
            return res.send(500, error);   
        }
    });
};

exports.sendMessageToQueue = function (req, res) {
    var body = req.body;

    var message = {
        body: 'Test message',
        customProperties: {
            testproperty: 'TestValue'
        }};

    serviceBusService.sendQueueMessage(body.queueName, message, function(error){
        if(!error){
            // message sent
            return res.send(200);
        } else {
            return res.send(500, error);   
        }
    });
}

exports.receiveMessageFromQueue = function (req, res) {
    var body = req.body;

    serviceBusService.receiveQueueMessage(body.queueName, function(error, receivedMessage){
        if(!error){
            console.log(receivedMessage);

            // Message received and deleted
            return res.send(200,receivedMessage);
        }  else {
            return res.send(500, error);   
        }
    });
}

function _receiveMessageFromQueue(queueName,delayTimeIfQueueIsEmpty,callback) {
    serviceBusService.receiveQueueMessage(queueName, function(error, receivedMessage){
        console.log(error, receivedMessage);
        // console.log(error);
        if (error == 'No messages to receive') {
            // call the rest of the code and have it execute after 30 seconds
            setTimeout(function() {
                callback(receivedMessage);
            }, delayTimeIfQueueIsEmpty);
        } else {
            // callback immediately
            callback(receivedMessage);
        }
    });
}

function _sendQueueMessage(queueName,message,callback) {
    serviceBusService.sendQueueMessage(queueName, message, function(error){
        console.log(error);
        callback();
    });
}

function listenMessageQueue(concurrency,delayTimeIfQueueIsEmpty,queueName) {

    var taskHandler = function(task, done) {
        _receiveMessageFromQueue(task.queueName, delayTimeIfQueueIsEmpty, function(message) {
            if (message) {
                console.log('hello ' + message.body);
            }

            myQueue.push({ id: task.id + 1, queueName: queueName, url: "http://localhost/get-person/" + task.id + 1});

            done();
        });
      };

    var queueSize = concurrency;

    var myQueue = async.queue(taskHandler, queueSize);

    myQueue.drain = function() {
        console.log("All the work has been done.");
    }

    for(var i = 0; i < concurrency; i++) {
        myQueue.push({ id: i, queueName: queueName, url: "http://localhost/get-person/"+i });
    }

}

function pushMessageQueue(concurrency,queueName) {

    var taskHandler = function(task, done) {

        var message = {
            body: String(task.id),
            customProperties: {
                url: task.url
            }};

        _sendQueueMessage(task.queueName, message, function() {
            console.log('hello ' + task.id);
            myQueue.push({ id: task.id + 1, queueName: queueName, url: "http://localhost/get-person/" + task.id + 1});
            done();
        });
      };

    var queueSize = concurrency;

    var myQueue = async.queue(taskHandler, queueSize);

    myQueue.drain = function() {
        console.log("All the work has been done.");
    }

    for(var i = 0; i < concurrency; i++) {
        myQueue.push({ id: i, queueName: queueName, url: "http://localhost/get-person/"+i });
    }

}

concurrency = 2;
queueName = "jobs";
pushMessageQueue(concurrency,queueName); // push message to queue for testing: 100 messages per call

Answer 1

finally was able to get through to Azure support and found the answer. ServiceBus by default enables partitioning. When making http requests (the NodeJS SDK for Azure ServiceBus makes http REST calls), when message count is low can result in a partitions with different sets of messages, as they have not had a chance to sync. This is resolved by creating a new Queue that disables partitioning or by increasing the keep alive or by using the DotNet SDK which allows https requests to be made.