Speed up Azure Service Bus Messaging with Batching

The Azure ServiceBus SDK gives us the QueueClient class which has convenient Send and Receive methods to send and receive a BrokeredMessage. But you need to be aware that sending and receiving messages individually is actually pretty inefficient compared to batching them up.

I did a quick test to see how long it would take to send 1000 messages individually with QueueClient.Send, and then receive them individually with QueueClient.Receive, and call BrokeredMessage.Complete on each one. Timings from five test runs are here:

Send (ms)	Receive (ms)
116564	276516
108713	262315
128817	295855
102973	255273
103937	251110

That’s sending a fairly pitiful 8 messages a second, and receiving is even slower at around 3-4 messages per second received and completed. And these messages aren’t even particularly large.

Here’s the sending code:

for (int n = 0; n < messages; n++)
{
    var body = $"Hello World, this is message {n}";
    var message = new BrokeredMessage(body);
    message.Properties["From"] = "Mark Heath";
    client.Send(message);
}

And here’s the receiving code:

while (received < messages)
{
    var message = client.Receive();
    if (message == null) break;
    received++;
    message.Complete();
}

Now let’s do the same thing, but using QueueClient.SendBatch and QueueClient.ReceiveBatch and QueueClient.CompleteBatch to receive and complete them.

Here’s the timings from five test runs:

Send (ms)	Receive (ms)
229	368
198	316
196	371
199	364
203	421

That’s right,  we can send all 1000, receive them and complete them in less than a second! We’re talking a speedup of over 500 times! Obviously your mileage might vary depending on your network speed and the size of the messages, but that’s still pretty incredible.

Here’s the batched sending code, which is very straightforward – just pass in an IEnumerable<BrokeredMessage>

client.SendBatch(Enumerable.Range(0, messages).Select(n =>
{
    var body = $"Hello World, this is message {n}";
    var message = new BrokeredMessage(body);
    message.Properties["From"] = "Mark Heath";
    return message;
}));

And the batched receiving code, which is also simple. Just specify how many messages you’d like in your batch and how long you want to wait before returning if there are less than that number. And to complete in a batch, you need the LockToken from each BrokeredMessage:

while (received < messages)
{
    var rx = client.ReceiveBatch(messages, TimeSpan.FromSeconds(5)).ToList();
    Console.WriteLine("Received a batch of {0}", rx.Count);
    if (rx.Count > 0)
    {
        client.CompleteBatch(rx.Select(m => m.LockToken));
        received += rx.Count;
    }
}

Now obviously not all applications lend themselves well to batching up sends or receives, but as you can see, the performance gains are so significant, it’s well worth doing wherever possible.

If you want to try this for yourself, I created LINQPad scripts in both C# and F#, which you can access in this Gist. All you need to do is provide your own Service Bus connection string.

Or you can view the F# version of my test app here:

let timed fn action =
    let s = new Stopwatch()
    printfn "Starting %s" action
    s.Start()
    fn()
    printfn "Took %dms %s" s.ElapsedMilliseconds action

let ensureQueueExists (nm:NamespaceManager) qn =
    if not (nm.QueueExists qn) then
        nm.CreateQueue qn |> ignore

let ensureQueueIsEmpty (nm:NamespaceManager) qn =
    let qd = nm.GetQueue qn
    if qd.MessageCountDetails.ActiveMessageCount > 0L then
        failwithf "%s has %d messages" qn qd.MessageCountDetails.ActiveMessageCount

let makeMessage n =
    let body = sprintf "Hello World, this is message %d" n
    let message = new BrokeredMessage (body)
    message.Properties.["From"] <- "Mark Heath"
    message
    
let sendIndividually (qc:QueueClient) count =
    let sendOne n = qc.Send (makeMessage n)
    [1..count] |> List.iter sendOne

let receiveIndividually (qc:QueueClient) count =    
    let rx = [1..count] 
                |> Seq.map (fun _ -> qc.Receive()) 
                |> Seq.takeWhile (fun bm -> not (bm = null)) 
                |> Seq.map (fun bm -> bm.Complete())
                |> Seq.length
    printfn "Got %d messages" rx

let sendBatched (qc:QueueClient) count =
    [1..count] |> List.map makeMessage |> qc.SendBatch

let rec receiveBatched (qc:QueueClient) batchSize runningTotal =
    let timeout = TimeSpan.FromSeconds 5.0
    let rx = qc.ReceiveBatch(batchSize, timeout) |> Seq.toArray
    match rx with 
    | [||] ->     
        printfn "Empty batch, total received %d" runningTotal
    | _ -> 
        let rxCount = rx.Length
        printfn "Got batch of %d messages" rxCount
        qc.CompleteBatch (rx |> Array.map (fun m -> m.LockToken))
        let totalSoFar = runningTotal + rxCount
        if totalSoFar < batchSize then
            receiveBatched qc batchSize totalSoFar

let connectionString = Util.GetPassword "Test Azure Service Bus Connection String"
let nm = NamespaceManager.CreateFromConnectionString connectionString
let queueName = "MarkHeathTestQueue"
let messages = 1000

ensureQueueExists nm queueName
ensureQueueIsEmpty nm queueName

let client = QueueClient.CreateFromConnectionString (connectionString, queueName)

timed (fun () -> sendIndividually client messages) (sprintf "Sending %d messages individually" messages)

timed (fun () -> receiveIndividually client messages) "Receiving messages individually" 

timed (fun () -> sendBatched client messages) (sprintf "Sending %d messages batched" messages)

timed (fun () -> receiveBatched client messages 0) "Receiving messages batched"

ensureQueueIsEmpty nm queueName