Azure Functions have a time limit of 10 minutes. Suppose I have a long-running task such as downloading a file that takes 1 hr to download.
[FunctionName("PerformDownload")]
[return: Queue("download-path-queue")]
public static async Task<string> RunAsync([QueueTrigger("download-url-queue")] string url, TraceWriter log)
{
string downloadPath = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString);
log.Info($"Downloading file at url {url} to {downloadPath} ...");
using (var client = new WebClient())
{
await client.DownloadFileAsync(new Uri(url), myLocalFilePath);
}
log.Info("Finished!");
}
Is there any hacky way to make something like this start and then resume in another function before the time limit expires? Or is there a better way altogether to integrate some long task like this into a workflow that uses Azure Functions?
(On a slightly related note, is plain Azure Web Jobs obsolete? I can't find it under Resources.)
Adding for others who might come across this post: Workflows composed of several Azure Functions can be created in code using the Durable Functions extension, which can be used to create orchestration functions that schedule async tasks, shut down, and are reawakened when said async work is complete.
They're not a direct solution for long-running tasks that require an open TCP port, such as downloading a file, (for that, a function running on an App Service Plan has no execution time limit), but it can be used to integrate such tasks into a larger workflow.
Is there any hacky way to make something like this start and then
resume in another function before the time limit expires?
If you are on a Consumption Plan you have no control over how long your Function App runs, and so it would not be reliable to use background threads that continue running after your Function entry point completes.
On an App Service plan you're running on VMs you pay for, so you can configure your Function App to run continuously. Also AFAIK you don't have to have a Function timeout on an App Service Plan, so your main Function entry point can run for as long as you want.
Or is there a better way altogether to integrate some long task like this into a workflow that uses Azure Functions?
Yes. Use Azure Data Factory to copy data into Blob Storage, and then process it. The Data Factory pipeline can call Functions both before and after the copy activity.
One additional option, depending on the details of your workload, is to take advantage of Azure Container Instances. You can have your Azure Function spin up a container, process your workload (download your file \ do some processing, etc), and then shut down your container for you. Spin up time is typically a few seconds and you only pay for what you use (no need for a dedicated app service plan or vm instance). More details on ACI here.
10 minutes (based on the timeout setting in the host.json file) after the last function of your function app has been triggered, the VM running your function app will stop.
To prevent this behavior to happen, you can have an empty Timertrigger function that runs every 5 minutes. it wont cost anything and will keep your app up and running.
I think the issue is related with the Cold Start state. Here you can find more details about it.
https://markheath.net/post/avoiding-azure-functions-cold-starts
What you can do is, create an trigger azure function that "ping" your long running function to keep it "warm"
namespace NewProject
{
public static class PingTimer
{
[FunctionName("PingTimer")]
public static async Task Run([TimerTrigger("0 */4 * * * *")]TimerInfo myTimer, TraceWriter log)
{
// This CRON job executes every 4 minutes
log.Info($"PingTimer function executed at: {DateTime.Now}");
var client = new HttpClient();
string url = #"<Azure function URL>";
var result = await client.GetAsync(new Uri(url));
log.Info($"PingTimer function executed completed at: {DateTime.Now}");
}
}}
Related
I'm getting a MessageLockLostException when performing a complete operation on Azure Service Bus after performing a long operation of 30 minutes to over an hour. I want this process to scale and be resilient to failures so I keep hold of the Message lock and renew it well within the default lock duration of 1 minute. However when I try to complete the message at the end, even though I can see all the lock renewals have occurred at the correct time I get a MessageLockLostException. I want to scale this up in the future however there is currently only one instance of the application and I can confirm that the message still exists on the Service Bus Subscription after it errors so the problem is definitely around the lock.
Here are the steps I take.
Obtain a message and configure a lock
messages = await Receiver.ReceiveAsync(1, TimeSpan.FromSeconds(10)).ConfigureAwait(false);
var message = messages[0];
var messageBody = GetTypedMessageContent(message);
Messages.TryAdd(messageBody, message);
LockTimers.TryAdd(
messageBody,
new Timer(
async _ =>
{
if (Messages.TryGetValue(messageBody, out var msg))
{
await Receiver.RenewLockAsync(msg.SystemProperties.LockToken).ConfigureAwait(false);
}
},
null,
TimeSpan.FromSeconds(Config.ReceiverInfo.LockRenewalTimeThreshold),
TimeSpan.FromSeconds(Config.ReceiverInfo.LockRenewalTimeThreshold)));
Perform the long running process
Complete the message
internal async Task Complete(T message)
{
if (Messages.TryGetValue(message, out var msg))
{
await Receiver.RenewLockAsync(msg.SystemProperties.LockToken);
await Receiver.CompleteAsync(msg.SystemProperties.LockToken).ConfigureAwait(false);
}
}
The code above is a stripped down version of what's there, I removed some try catch error handling and logging we have but I can confirm that when debugging the issue I can see the timer execute on time. It's just the "CompleteAsync" that fails.
Additional Info;
Service Bus Topic has Partitioning Enabled
I have tried renewing it at 80% of the threshold (48 seconds), 30% of the Threshold (18 seconds) and 10% of the Threshold (6 seconds)
I've searched around for an answer and the closest thing I found was this article but it's from 2016.
I couldn't get it to fail in a standalone Console Application so I don't know if it's something I'm doing in my Application but I can confirm that the lock renewal occurs for the duration of the processing and returns the correct DateTime for the updated lock, I'd expect if the lock was truely lost that the CompleteAsync would fail
I'm using the Microsoft.Azure.ServiceBus nuget package Version="4.1.3"
My Application is Dotnet Core 3.1 and uses a Service Bus Wrapper Package which is written in Dotnet Standard 2.1
The message completes if you don't hold onto it for a long time and occasionally completes even when you do.
Any help or advice on how I could complete my Service Bus message successfully after an hour would be great
The issue here wasn't with my code. It was with Partitioning on the Service Bus topic. If you search around there are some issues on the Microsoft GitHub around completion of messages. That's not important anyway because the fix I used here was to use the Subscription forwarding feature to move the message to a new Topic with partitioning disabled and then read the message from that new topic and I was able to use the exact same code to keep the message locked for a long time and still complete it successfully
Scenario: A Azure WebJob that will get all the Vendor record from NetSuite via WSDL.
Problem: The dataset is too large. Even with service set to 12 minutes time out. It still time out and the code failed.
NetSuite have a async process that basically run whatever you want on the server and it will return a JobId that allowed you to check the process on the server.
What I did currently is by making a search call first asking for all the Vendor records and it is to be process on the server. After I got the JobId, i wrote a void Recursion that check if the job is finish on the server with Thread Sleep set to 10 minutes.
private static bool ChkProcess(VendorsService vendorService, string jobId)
{
var isJobDone = false;
//Recursion
void ChkAsyncProgress(bool isFinish)
{
if (isFinish) return;
var chkJobProgress = vendorService.NsCheckProcessStatus(jobId);
if (chkJobProgress.OperationResult.IsFinish) isJobDone = true;
Thread.Sleep(TimeSpan.FromMinutes(10));
ChkAsyncProgress(isJobDone);
}
ChkAsyncProgress(false);
return isJobDone;
}
It work but is there a better approach?
Thanks
I think that since you're working with Azure already, with Service BUS you can implement a really low cost solution for this (if not free, depending on how much frequent is your job running)
Basically it's a queue where you enqueue messages (which can be objects with properties too, so they could also contain your result of the elaboration potentially).
A service bus is used to enqueue.
An azure function of type ServiceBusTrigger listens automatically if any new message on service bus has arrived and gets triggered if so (or, you can set messages to be enqueued, but be available after a certain future time only).
So, in the webjob code, at the end you could add code to enqueue a message which will mark the webjob has finished elaboration.
The azure function will get immediately noticed as soon as the message gets in the queue and you can retrieve the data without polling constantly for job completion, as azure will take care of all of that for you for a ridiculous price and without any effort by you.
Also, these task aren't priced timely based, but execution based, so you will pay only when it effectively put a message in queue.
They have a certain number of executions free, so it might be that you don't even need to pay anything.
Here some microsoft code sample for doing so.
I am new to azure web app, Is there any way to redirect the page first then execute the remaining code? I am stuck in situation where I have to redirect my page first, then execute the remaining code... Actually I have deployed my code on azure web app which has request timeout for about 4 mins (which is not configurable), my code take approx 15 min to execute, I want to redirect to main page and execute the remaining code in background. I have tried threads and parallel programming also still no luck.. I am not able to overcome the time frame my web page get request time out every time. Is there a way anyone can suggest?
Thanks for help!
/*functionA and functionB are not execute after redirecting.*/
private static async Task <int> functionA(para1, para2)
{
Task<int> temp1 = await functionB(y,z);
return int;
}
private static async Task<int> functionB(para1, para2)
{
return int;
}
/* This method will execute first */
private string functionC(para1, para2, para3)
{
console.log("hello world");
redirect.response("www.xyz.com");
Task<int> temp = await functionA(x,y);
return str; //return string type value
}
If you've got heavy processing that will result in a HTTP timeout, I suggest looking into offloading processing to a WebJob or Azure Function. It would work as follows:
Your Azure WebApp receives a HTTP request for a long-running operation. It gathers the necessary information, creates a Service Bus Queue message, and fires the message off. Your WebApp then responds to the user by telling them that the processing has begun.
Provision a separate WebJob or Azure Function that monitors your Service Bus Queue for messages. When a message is received, the WebJob/Function can perform the processing.
You will probably want to tell your user when the operation has completed and what the result is. You have a few options. The slickest would be to use SignalR to push notifications that the operation has completed to your users. A less sophisticated would be to have your WebJob/Function update a database record, then have your HTTP clients poll for the result.
I've personally used this pattern with Service Bus Queues/WebJobs/SignalR, and have been very pleased with the results.
Asynchronous operations in Azure storage queues and WebJobs can help in situation as stated
i have referred this
https://dev.office.com/patterns-and-practices-detail/2254
I want to create some functions in ASP.NET Web API, which should be executed daily at specific time and do specific task like update statuses/Records/Generating Emails, SMS.
Should i create a TaskService in Code
using System;
using Microsoft.Win32.TaskScheduler;
class Program
{
static void Main(string[] args)
{
// Get the service on the local machine
using (TaskService ts = new TaskService())
{
// Create a new task definition and assign properties
TaskDefinition td = ts.NewTask();
td.RegistrationInfo.Description = "Does something";
// Create a trigger that will fire the task at this time every other day
td.Triggers.Add(new DailyTrigger { DaysInterval = 2 });
// Create an action that will launch Notepad whenever the trigger fires
td.Actions.Add(new ExecAction("notepad.exe", "c:\\test.log", null));
// Register the task in the root folder
ts.RootFolder.RegisterTaskDefinition(#"Test", td);
// Remove the task we just created
ts.RootFolder.DeleteTask("Test");
}
}
}
or should i create a .bat file and create a new task in Task Scheduler.
As you have mentioned in the question, you need to do the specific tasks like update statuses/Records/Generating Emails, SMS etc.
So database access comes into the scenario and on the other hand, you will have to send emails and SMS's which may require third party libraries or other configuration setting access.
Thus, to do all this it will be better to go with code implementation via which you can maintain your changes and requirements well enough.
About the ".bat file and windows scheduler", you need to have great skills using the limited batch commands available to fulfill your requirement.
So, my suggestion is code, .exe and windows scheduler task.
Also, this should be a separate application, don't mix it up with Web API code. You can always create a new project in the web API solution with web API project and reuse whatever code is possible.
You should do this outside your web code. This is because your webapp should have no access to the task system or web service. By default IIS 7.5+ runs app's in their own limited user account (https://www.iis.net/learn/manage/configuring-security/application-pool-identities).
If you want to have a reliable tasks scheduling wherein you can apply time interval depend on your choice, I recommend [quartz]: https://www.quartz-scheduler.net/. Quartz allow to add/edit/delete/etc a scheduled task easily, manageable and no CPU overhead.
Moreover Quartz is an open source job scheduling system that can be used from smallest apps to large scale enterprise systems.
I recommend you to try Hangfire. It's free and you can use it for free in commercial app. Ducumentation you can find here.
I want to trigger an Azure Webjob 24Hours after I have added a record to a database using .NET . Obviously there will be multiple tasks for the Webjob to handle, all at their designated time. Is there a way ( in the Azure Library for .NET) in which i can schedule this tasks ?
I am free to use Message Queues , but I want to try and avoid the unnecessary polling of the WebJob for new messages.
If you want to trigger the execution of a WebJob 24 hours after a record insertion in a SQL database I would definitely use Azure Queues for this. So after you insert the record, just add a message to the queue.
In order to do this you can easily leverage the initialVisibilityDelay property that can be passed to the CloudQueue.AddMessage() method. This will make the message invisible for 24 hours in your case, and then it will appear to be processed by your Webjob. You don't have to schedule anything, just have a Continuous WebJob listening to a queue running.
Here's some sample code:
public void AddMessage(T message, TimeSpan visibilityDelay)
{
var serializedMessage = JsonConvert.SerializeObject(message);
var queue = GetQueueReference(message);
queue.AddMessage(new CloudQueueMessage(serializedMessage), null, visibilityDelay);
}
private static CloudQueue GetQueueReference(T message)
{
var storageAccount = CloudStorageAccount.Parse("Insert connection string");
var queueClient = storageAccount.CreateCloudQueueClient();
var queueReference = queueClient.GetQueueReference("Insert Queue Name");
queueReference.CreateIfNotExists();
return queueReference;
}
Hope this helps
Since the event of adding a record to the database is the trigger here, You can use Azure Management Libraries to create a Azure Scheduler Job to execute after 24hrs from the time the db record is inserted. Azure Scheduler Jobs can do only 3 things : make HTTP/HTTPS requests or Put Message in Queue. Since you do not want to poll queues, here are two options
Deploy the existing Web Job as Wep API where each task is reachable by unique URLs, so that the scheduler task can execute the right HTTP/HTTPS request
Create a new WebAPI/Wep API which takes accepts request (like a man in the middle) and pro-grammatically run the existing web job on demand, again using Azure management libraries.
Please let me know if any of these strategies help.
To invoke a WebJob from your Website,is not good idea rather than you can add the WebJob code inside your Website and simply call that code. you can still easily use the WebJob SDK from inside your Website.
https://github.com/Azure/azure-webjobs-sdk-samples
we wouldn't recommend to invoke the WebJob from your Website is that the invocation contains a secret you rather not store on your Website (deployment credentials).
Recommendation:
To separate WebJob and Website code, the best thing to do is to communicate using a queue, the WebJob listens on the queue and the Website pushes the request to the queue.