Develop Reference

First Call to Web API is very slow C#

I have my Asp.Net WebApi hosted on Godaddy windows shared hosting.
When I access my api from different devices/machines, It takes around 30 sec for first request; after that, it works fine.
What is the issue? Can I make my web api run all the time? If so, how?
I have used Entity framework code first approach . Every time I face this issue when I call this api from my website which is:
Rs Travels - Go to holidays, click on domestic, see the slowness of web api.
Is there any way I can improve the performance of the web api?

If the API is not used often, it will take time on the first request to make things ready, it's the same if you restart IIS generally, things need to warm up.
Internally, we have a custom healthcheck system that calls specific URLs to monitor them, but as a consequence, it also keeps the service alive.
You could also do this fairly simply by creating a windows scheduler task locally, or on any server that simply calls the API periodically. It might be best to implement a specific Monitor method that performs any other keepalives that might be relevant.
Try this as an example Open Website from windows scheduler

It would be kinda difficult to change it since you do not own the web server (and thus its pool). You could try to call the api before you will actually need it (imagine a splash screen). Then it will be ready when you will actually need it. Of course, this will not work if form the initial page you are calling the API...

This worked for me !
https://stackoverflow.com/a/9474978/6426192
static Thread keepAliveThread = new Thread(KeepAlive);
protected void Application_Start()
{
keepAliveThread.Start();
}
protected void Application_End()
{
keepAliveThread.Abort();
}
static void KeepAlive()
{
while (true)
{
WebRequest req = WebRequest.Create("http://www.mywebsite.com/DummyPage.aspx");
req.GetResponse();
try
{
Thread.Sleep(60000);
}
catch (ThreadAbortException)
{
break;
}
}
}

Creating new AppDomain calling method in same class as the AppDomain in made

I want to start below potentially long running thread in it's own AppDomain to prevent the webserver from aborting it during recycling. It compiles fine, however during runtime I get this cryptic error
Type is not resolved for member 'MyCore.MyWebService,MyCore,
Version=5.0.0.0, Culture=neutral, PublicKeyToken=null'.
How do I find out what member is not resolved?
Are there any better ways running a long standing thread in a MVC business service layer, that does not get aborted by the server recycling mechanism?
Here is the code:
namespace MyCore
{
[Serializable]
public class MyWebService : IMyWebService
{
AppDomain domain = AppDomain.CreateDomain("Domain");
Thread.CurrentThread.Name = "MVCThread";
domain.SetData("lDatabaseID", lDatabaseID);
domain.DoCallBack(() =>
{
long lID = Convert.ToInt64(AppDomain.CurrentDomain.GetData("lDatabaseID"));
Thread thread = new Thread(
(() =>
{
PopulateTables(lID );
}));
thread.Name = "DomThread";
thread.Start();
});
}
}

IIS is heavily optimised to respond very quickly to hundreds of small simultaneous requests and just isn't the right tool for what you're attempting. You can try to work around that but in the long term you'll be better off building a tool that is designed for long-running tasks. You've then got a pre-packaged solution the next time this problem arises.
The basic idea is to create an external application that does your background processing with some way to pass tasks to it and get results back. I like using the database to communicate as most web applications that need baground processing already use a database. Add a 'tasks' table with {status, startedDateTime, finishedDateTime, parameters, etc}, then write an external application that will periodically look for a new task, complete it and update the database. Your web site can poll the database for status or your application could make an AJAX call to notify the web site when a job has completed (a small iframe in the web site header that shows waiting / completed tasks can be useful if someone will be waiting for the job to complete and is easy to do).
EDIT: Before you do the above review HangFire (which works inside IIS, as a Windows Service or as a console app). Same principles, but a pre-packaged solution. Note that I haven't implemented this yet but it looks good.
Although it's a bit of work to set up, handing this task off to a Windows Service is a good approach if you might have multiple tasks and need them responded to quickly. There are a lot of tutorials on the web that will help you create a Windows Service, such as http://www.codeproject.com/Articles/106742/Creating-a-simple-Windows-Service but you'll have to build a simple task executor on top of that so if that's the way you want to go I'd look for a pre-built task engine (I couldn't find one quickly but I'm probably using the wrong search phrase).
But that's overkill if turn-around time isn't important and a better approach for you might be to create a small console application that will be started every five minutes by task scheduler. It would connect to the database, execute any waiting tasks then shut down again. This is easier to debug and install than a Windows service and achieves the same goal of moving the task execution out of IIS.
Remember that you still have to detect and handle Windows shutdown so that you don't get half-finished orphaned jobs - at the very least just tag that task as aborted and exit cleanly.

Alright after having mucked with Hangfire, I finally got it to work in .Net 4.0 and MVC 3. Had to install Common.Logging.Core 2.2.0, since the NuGet installed the wrong version (3.3.0)
In my Initial controller I added the following
namespace Core.Controllers
{
...
public void Configuration(IAppBuilder app)
{
app.UseHangfire(config =>
{
config.UseSqlServerStorage(ConnectionString.GetTVConnectionString());
config.UseServer();
});
}
...
}
ConnectionString.GetTVConnectionString() gets the connection string from the config file.
Up top I added the following
[assembly: OwinStartup(typeof(Core.Controllers.BaseController))]
In the code that starts the background thread I added the following, passing in a long instead of the class and having the job load the POCO class from the db.
BackgroundJob.Enqueue(() => PopulateTables(lDatabaseID, JobCancellationToken.Null));
The Enqueue() function returns a job id, that later can be used to cancel the job if needed, through the BackgroundJob.Delete(jobid) function.
In the job method I then have this
while (idxMin < max)
{
try
{
cancellationToken.ThrowIfCancellationRequested();
....
}
catch (JobAbortedException jobEx)
{
....
}
}
It's important to use dependency injection, so my class had a parameter less constructor added that re-reads the connection string rather than have it passed in.
public MyWebService ()
: this(ConnectionString.GetTVConnectionString())
{
}
public MyWebService (string sConnStr)
{
msConnStr = sConnStr;
}
After that it seems to run pretty well. A number of tables are added to the database specified in the connection string. So far it seems like the jobs survive recycling on the webserver.

ASP MVC app resets on long running thread

In my ASP MVC 5 app I have this database related operation that I've to perform once in month maybe and it takes about 30 - 60 minutes.
I start this action like this:
Repository dbForCategories = new Repository();
dbForCategories.Database.CommandTimeout = 60000;
var t = Task.Factory.StartNew(async delegate
{
var crs = new ProductCategoryRelationsSetter(dbForCategories, categoryService);
crs.AddProductsCategoriesRelations(oneLineTree);
}, CancellationToken.None, TaskCreationOptions.LongRunning, TaskScheduler.Default);
After about 5 minutes of working in background Im getting logged out of application. I think that the app resets because some static variables Im using are reset.
In elmah i don't have any errors. I put my code in Try Catch block.
Only hope in you guys:)

As #David mentioned, it's probably best to go the Windows Service route:
Write the item to a database table
Let a Windows Service poll the table every month (or however often you need it to).
If it finds a new item in the queue, let the Windows Service perform the operation.
Why not do Background threads in ASP.NET?
The server may recycle Application pool at some point and will not know to wait for your Task on a separate thread. (Discussed in this SO question)
.NET 4.5.2 onward. You can fire and forget short tasks
For interest sake you can use HostingEnvironment.QueueBackgroundWorkItem (see here) and the server will respect the background item and not recyle the App pool while it's busy, BUT ONLY for up to 90 seconds. anything longer and Windows Service is your best bet.
HostingEnvironment.QueueBackgroundWorkItem(ct => yourAsyncWork(ct));

Hangfire is wonderful for stuff like this.
https://www.nuget.org/packages/Hangfire/

how to create cron job in asp.net(v4.0) to run method every 30mins

I need some guidance on creating and running a Cron Job in asp.net(C#.net) to run every 30 minutes.i have created a class in that i have written code for getting tweets, facebook feeds.
i have created another page in that i have one button to download tweets and save in database.
If i want to get tweets i have to click on sync button every time.
i want to create cron job so that the database will get automatically synchronized with new tweets,facebook feeds.
Thanks

You can follow any one of the following approaches
Create a console app with the logic to fetch the tweets and feeds, and use a Task scheduler to run it for every 30 mins.
You could build a windows service, which polls the feeds within a timer and updates the db.
You could checkout this scheduler which is a rough equivalent to cron jobs. Personally haven't tried it. Check out this SO

If your intended 30-minute scheduled task is meant to be a discrete transactional action (like, for instance, your example of synchronizing some database values), then you may want to take a look at the Revalee open source project.
You can use it to schedule web callbacks at specific times. In your case, you could schedule a web callback (30 minutes in the future). When your ASP.NET application receives the callback, it can schedule the next 30 minute callback as well as perform whatever tasks you need it to handle every half-hour. When your ASP.NET application launches for the very first time, then you would schedule the first web callback. Since your web application is being called back, you do not need to worry about your web application unloading (which it will do periodically on IIS, for example).
For example using Revalee, you might do the following:
Register a future (30 minutes from now) callback when your application launches via the ScheduleThirtyMinuteCallback() method (see below).
private DateTimeOffet? previousCallbackTime = null;
private void ScheduleThirtyMinuteCallback()
{
// Schedule your callback 30 minutes from now
DateTimeOffset callbackTime = DateTimeOffset.Now.AddMinutes(30.0);
// Your web service's Uri, including any query string parameters your app might need
Uri callbackUrl = new Uri("http://yourwebapp.com/Callback.aspx");
// Register the callback request with the Revalee service
RevaleeRegistrar.ScheduleCallback(callbackTime, callbackUrl);
previousCallbackTime = callbackTime;
}
When the web scheduled task activates and calls your application back, you perform whatever action you need to do every 30 minutes and you schedule the next callback too. You do this by adding the following method call (CallbackMonitor()) to your Callback.aspx page handler.
private void CallbackMonitor()
{
if (!previousCallbackTime.HasValue
|| previousCallbackTime.Value <= DateTimeOffset.Now.AddMinutes(-30.0))
{
// Perform your "30 minutes have elapsed"-related tasks
// ...do your work here...
// Schedule subsequent 30 minute callback
ScheduleThirtyMinuteCallback();
}
}
To be clear, the Revalee Service is not an external 3rd party online scheduler service, but instead a Windows Service that you install and fully control on your own network. It resides and runs on a server of your own choosing, most likely your web server (but this is not a requirement), where it can receive callback registration requests from your ASP.NET application.
If, however, your 'run every 30 minutes' task is a long running task, then you probably do not want to embed that functionality within your ASP.NET application.
I hope this helps.
Disclaimer: I was one of the developers involved with the Revalee project. To be clear, however, Revalee is free, open source software. The source code is available on GitHub.

How to run long-lasting process asynchronously under asp.net?

.net 4.5, asp.net mvc: What is the best way to run long-lasting process (1-2 minutes) from ASP.NET application giving it should be run in a single-threaded environment, I mean the process is initiated for one user at a time only, executions for all other users have to wait till the current execution is done? The scenario is the following: user clicks button that run some sort of long-lasting calculations, http response returned to the user immediately, then user has to request status of the calculations with separate request manually. Asp.net http session abortion should not lead to the process termination, it should keep going. The process might be run on the same or separate server.

I'll show you how to perform this task with http://hangfire.io – incredibly easy way to perform fire-and-forget, delayed and recurring tasks inside ASP.NET applications. No Windows Service required.
First, install the package through NuGet. If you have any problems, please see the Quick Start guide in the official documentation.
PM> Install-Package Hangfire
Open your OWIN Startup class and add the following lines:
public void Configure(IAppBuilder app)
{
GlobalConfiguration.Configuration.UseSqlServerStorage("connection_string");
app.UseHangfireDashboard();
app.UseHangfireServer();
}
Then write the method that will do the long-running work (I applied attribute to perform only one method at a time):
[DisableConcurrentExecution]
public void LongRunning()
{
// Some processing stuff
}
And then call a method in background as fire-and-forget to respond user immediately:
public ActionResult Perform()
{
BackgroundJob.Enqueue(() => LongRunning());
return View();
}
If you want to notify a user about job completion, consider using SignalR and append the LongRunning method correspondingly.

.Net 4.5.2 adds QueueBackgroundWorkItem that you can use to schedule a task. If you don't control the server (when it's rebooted), the 90 second default delay of appPool shut down won't work (unless you can detect the task didn't complete and run it on another server). For more details see "QueueBackgroundWorkItem to reliably schedule and run background processes in ASP.NET"

I would suggest using a product such as NServiceBus to offload the processing and run it in single threaded mode. The advantage to this is that all requests will be processed in order and the processing can be offloaded from the web server as you don't really want long running processes to happen on a web server.

If you control the server, and need more simplicity that a full framework like Hangfire, you can make a console app (.exe), and make any thing..., then you can call the .exe with Process.Start Method, you can call the .exe from SQL Server to, service, etc.