System.Threading.Tasks - Limit The Number Of Concurrent Tasks?
May 24, 2010
I have just started to look at the new "System.Threading.Tasks" goodness in .Net 4.0, and would like to know if there is any build in support for limiting the number of concurrent tasks that run at once, or if this should be manually handled.
E.G: If I need to call a calculation method 100 times, is there a way to set up 100 Tasks, but have only 5 execute simultaneously? The answer may just be to create 5 tasks, call Task.WaitAny, and create a new Task as each previous one finishes. I just want to make sure I am not missing a trick if there is a better way to do this.
In my ASP.NET website, I am having a function which has to be automatically performed once every 2-3 mins on its own, i.e. without user intervention. This function contains database access.
Can I use threading to perform this process in background?
If Yes, How can I use that?
Edit
Also I am not looking for a solution which includes windows service because I am using shared hosting. So I dont have all the rights to access the host computer.
I am a beginner of C# programming. I have read a few books about C#.net. But I cannot find some exercises in the books. Someone told me to build up a blog to practice my coding.
But it is a huge task for a beginner. I just want some tasks to have a step by step learning process.
I used Castle Windsor before and had this routine that fired the certain method of all classes that implement a certain interface.If I recall correctly, the interface was IBootStrapTask and only had an excecute method. Then, for instance, I'd place all my route registrations in one of these, and know it get fired on application startup.Have to admit I did not understand the code to well, so I'm even more unsure how can I do this. I'm using structure map now. (still knowing very little about it)
When we talk about WebForms we say, for Administrative tasks, you must have an Admin folder to separate the admin task.
In MVC how i will treat my Admin tasks?
I will go for Admin Area or Admin Controllers,
Because if i will write controller for Admin tasks, each and every task will be written in one controller (AdminController) or if i will write Area -> Controller, means i will need to write at-least two controllers for each feature.
Second if we breaks the application in Areas (as modules) how i will manage Admin task for each Area.
We have a timer process (a JQuery plugin) that redirects after X number of minutes to the login page, all via JavaScript. When the timer hits zero, I want to run a task (could be anything; however, in this specific scenario, it's a web service call).
The issue I'm having is the web service that runs with the finish-up processes is not being called. The web service call happens, the redirect happens, I don't see any errors (I have try/catch statements around the setTimeout call), but no WS call.
As part of the web application I am working on there will be functionality to export data from the web application into a windows application copying the data between the database for the web application and the windows application. The databases for these two programs could have been combined but are being kept apart for simplicity.The utility to export the data can be triggered manually from the web application but it is also required that this task can be scheduled to run by the user (once a day, on web app shutdown etc)
I envisage this to be run as a service - I have created services for windows applications before but this is the first time I have needed to create this for a web application. Searching on goggle, I have found an msdn magazine article that suggests creating a web service and then creating a windows service which would call into this web service. So in my situation, I am thinking that I would create a web service which would contain the data transfer functionality between the web application and the windows application. Then I would create a windows service which would be installed as part of installing the web application, which would then call into the web service (at pre-defined intervals) using settings configured by the user within the web application (so that the data transfer functionality can be scheduled).Does this seem the correct solution? I would appreciate any advice on how I might achieve the above.
I need reliable way to run 10 different tasks simultaneously. For instance the first one would be sending emails, while the next one is cleaning rows from a specific table... so on an so forth.
I've used the Thread class and while it works well on my development machine (VS2010 internal web server) non of these threads seems to be working at all on my production server. And I don't know of an effective way to debug the problem on the production server.
I saw this technique which encourage you to register cache objects. Since the application fires a callback when a cached item expires, then it's possible to run any code to mimic threading behavior. It seems a little Micky Mouse like.
This is my first forray into ASP.NET MVC, having been doing WebForms for nearly 6 years now. I've read through various tutorials and guides on getting started with MVC, but I've a few questions about how you're meant to do things:
UserControls for entities
In an application I wrote a few years ago (using WebForms) there were many entities that had an associated postal address (which existed as an instance of an Address class), so I created a UserControl that contained fields for working with addresses. During the page lifecycle I would pass the business object's .Address property to the UserControl for display and for population upon a successful and valid postback. How would I do something like this in MVC? My current project has a similar situation where common sets of fields are repeated throughout the application and all 'map' to the same class.
Modifying the page/view on 'postback'
Say I'm working on a data-entry form for an online B2B ordering system, where the user manually enters order items into a series of textboxes arranged in a table. The system can only provide so-many textboxes at a time (usually 5 or 10). If the user ran out of textboxes they would click an "Add more rows" button that performed a postback that was caught by that button's server-side .Click event handler. The page's class would then add more rows to the page; ASP.NET's stateful nature made this easy to implement. But in MVC there is no ViewState and I haven't found much information about how you'd do this, or anything like this. All of the tutorials and guides assume a form posting is only for data submission.
Multiple tasks per page/form
In a similar vein to the above, how do you create views that perform multiple tasks? In my above example I cited a webform that had two buttons: one to submit the form for actual processing, and another button that just modified the page (by adding more data-entry rows).Given that Controllers' actions are bound to URIs rather than what combination of fields were submitted, does this mean that I would have to interpret the posted data myself and branch based on that?
Finally, in many web applications you have the main form in the middle, but also things on the periphary of the page (e.g. a sidebar) that might have their own logic. For example, in one WebForms application I wrote last year there was a 'Quick contact' form in a UserControl located elsewhere on the page. When the user clicked the form's button the UserControl's logic handled the postback details independently of the page containing the UserControl (but there was only one <form> element in the whole rendered page). The user was returned to the page they clicked the button on, with everything in identical state as to how it was before, exccept for the UserControl which reported that the email was sent. Again, MVC's stateless nature would make something like this hard to implement, unless there are some techniques not covered in the tutorials?
I am experimenting AsyncController feature. What I did is set up two tasks to run in parallel. As in the code below, the problem is that sometime all tasks finished and return successfully, sometime only one task finish and sometime each task finish half of it's work and return. It is weird, what did I do wrong?
I have realized that Trace.Write is not a good way of tracing as it is gives you the time since last entry which makes no sense if more threads are writing.
I am writing a quick-and-dirty in-house ASP.NET application that needs to be able to run a task after a specific period of time. If it was a proper application, I'd probably use a windows service but I don't really want to bother with the extra complexity of that.I could put code in the BeginRequest handler to check whether any such tasks are due, but of course nothing would happen if nobody is using the application.at the moment the best option I can think of is something like ShellExecute("nohup sleep 1000; wget http://server/dummypage.aspx") (if you'll excuse the mixed windows/unix nomenclature).
I would like to makea windows service. whenever the user of my ASP.NET application has to do a time-consuming task, the IIS would give the task to the service which will return a token(a temporary name for the task) and in the background the service would do the task. At anytime, the user would see the status of his/her task which would be either pending in queue, processing, or completed. The service would do a fixed number of jobs in parallel, and would keep a queue for the next-incoming tasks. In addition there would be a WinForms application for system administrator that would allow adding special ADMIn tasks such as "Clean orphaned files" or "archive data of inactive users".
Can you point me to something that can jump start me on this as a whole concept - I know I can google for windows services and I am able to do it myself from scratch but time is of the Essence so maybe you know of something that is already there and i can use block to build out of.
I'm looking for ways to improve a web page that initiates a long-running (>2 minutes) server-side task. The current version of the page just clocks for the full duration of the task, which can be very frustrating to the user.
I already have a few ideas about how I could improve the user's experience, but they all would involve the use of AJAX to some extent. Because of previous experiences that I've had on this project, I know that not all users have JavaScript enabled or available.
Assuming that the server-side process has already been optimized as much as possible, what else could I do to improve the experience of all users as much as possible?
and so on (many more records). Now, whenever a record reaches its' end time, how can I execute SQL commands to delete that data (or mark as finished) and UPDATE another table?
This needs to be running constantly so I was thinking of building it into a Windows Service but can you suggest a better way of doing it?
My application have 2 Roles. Admin and Student. I created some tasks for these 2 roles by using LoginView ( Edit RoleGroup). As user login both can see there allocated tasks.
But I want to allocate some admin tasks to some student(s) not for all. How can I do it?
I am into shared hosting and they do not allow me to use windows scheduler... So what are the ways of achieving scheduled tasks ie(timed mail) in asp.net... I just saw background process by Jeff Atwood blog... Is it relaible? Or any other ways of doing scheduled tasks...
Then i found quartz.net but i can't find a simple example that embeds quartz.net into an asp.net(without installing a Quartz.Net server as a standalone windows service)...
I need to invoke a long running task from an ASP.NET page, and allow the user to view the tasks progress as it executes.
In my current case I want to import data from a series of data files into a database, but this involves a fair amount of processing. I would like the user to see how far through the files the task is, and any problems encountered along the way.
Due to limited processing resources I would like to queue the requests for this service.
I have recently looked at Windows Workflow and wondered if it might offer a solution?
I am thinking of a solution that might look like:
ASP.NET AJAX page -> WCF Service -> MSMQ -> Workflow Service *or* Windows Service
How to search text from Contacts/Tasks/Notes using textbox? I mean if I type "Test" he should find any Contacts/Tasks/Notes that contain word "test" in: tasks name, person name, person surname, person address, telephone number and notes.
I need two select buttons in my gridview for two different tasks and I'd like to change color of selected row.If I use command field selected row changes color, but I don't know how to distinguish which button has been chosen.If I use linkbutton I can pass commandname but selected row doesn't change color
3) Finally adding the reference of service contract project in a Hosting project (Console Application) with complete configurations.
I am adding one more windows app project as a client.When i am trying to add the service reference using the address "http://localhost:8000/Tasks", VS 2008 displays the below error.
There was an error downloading 'http://localhost:8000/Tasks'.
Unable to connect to the remote server
No connection could be made because the target machine actively refused it 127.0.0.1:8000
Metadata contains a reference that cannot be resolved: 'http://localhost:8000/Tasks'.
Could not connect to http://localhost:8000/Tasks. TCP error code 10061: No connection could be made because the target machine actively refused it 127.0.0.1:8000.
Unable to connect to the remote server
No connection could be made because the target machine actively refused it 127.0.0.1:8000
If the service is defined in the current solution, try building the solution and adding the service reference again.
