I have a web app that will run forever (at least for a few days) on my local machine using the technique (hack?) described in Jeff Atwood's post: https://blog.stackoverflow.com/2008/07/easy-background-tasks-in-aspnet/
However when I run it on App Harbor my app doesn't run for more than an hour or so (I'm not sure when it dies) as long as I hit the site it stays up so I'm assuming it is being killed after an idle period, but I'm not sure why.
My app doesn't save any state or persist anything. It makes web service calls and survives errors in any calls.
I turned on a ping service to keep my app alive but I'm curious why this works on my local machine but not on App Harbor?
The guys behind App Harbor pays for EC2 instances for all running apps, so they naturally want to limit the cpu usage as much as possible. One way to achieve this is to shut down unused applications very fast and only restart them when someone actually try to access them. Paid hosting should not be limited in this way.
(As far as I have been informed they are able to host around 100k sites on less than twenty medium instances which is certainly quite impressive and calls for a very economic use of resources.)
To overcome the limitation you would need a cron job to ping your app harbour site. But this of course a quite recursive problem since you need app harbour to act as a cron job ;)
AppHarbor recycles the Application Pool frequently to keep sleeping websites from using idle CPU time. This is simply the price you pay of using a shared website hosting plan.
If you really want to run a background job then you should be using AppHarbor's background workers, since this is exactly the type of task they were built to run.
http://support.appharbor.com/kb/getting-started/background-workers
Simply build a new console application that runs your logic and include it in your solution. When you push the code the workers will be started automatically. If you happen to already have other exe's in your solution make sure to edit the app.config and set the 'deploy background worker' value to false.
Related
I'm trying out Windows Azure free trial - as I understand, you can host up to 10 websites on the free account.
My question is: is there any way of hosting a website along with some kind of background processing or scheduled task with the free account on Azure? I'm almost sure that it's not because Web roles support that and not Web sites.
Is there any other alternative to host an ASP.NET MVC website with some kind of background processing on Azure for free? Everything would be purely for educational or personal purposes.
The free sites in Windows Azure Web Sites can technically run some background operations because you can spin up a background thread in the application start up; however, there are a several issues with this approach:
Idle sites will be shut down. This means that if the site isn't seeing a lot of traffic the process can be shut down. I'm not sure that the background processing would keep it alive, or even if it did how reliable that would be kicking off. It will depend heavily on the type of background processing I would think.
The web sites at the free level have CPU and memory quotas. Running something a lot in the background may cause you to hit these quota more often than if the site is more idle. Hitting the quota will shut down the site until a specific time period has past. Be very aware of these quotas if you are using the free or shared levels. If you were planning to have this background processing working a queue for instance this likely won't work out well.
You could use something like the free level of the Scheduler in the Windows Store app to kick off some work by having it call in to your web site and asynchronously kick off the back ground work. This might work and avoid the CPU quota if the amount of background work is pretty small and is completed quickly and with little resources used. Note that there is also a scheduler available with Mobile Services. For educational purposes this may just fine.
Don't forget that with the free trial you get $200 worth of Azure for 30 days. If you are really just trying things out you can easily spin up full cloud services, VMs or even shared web sites during the trial. If you shut them down when not actively working on them the $200 can give you a decent amount of time to try things out.
I have app that has few schedule tasks that get initiated at application start. These task execute the actions and then sleep for X amount of time. This works perfectly fine except for the task that run sleep longer then the default time set for recycling in the application pool.
Its a small application only intended for internal use. The app at most will only have 10-15 people logged in at the same time and the server only has this app hosted on it.
I was wondering if its safe to turn off recycling ?
I will tell you something from experience.
We do not recycling the pools and the sites run perfectly with out any issue ! The only time that we recycle pools is usual on next reboot.
Maybe in a share environment where many different programmers runs under the same pool, sites with problems and forgotten to close handlers the recycle is a must.
But inside a controlled environment where you are in control for what are running on the pool, are tested that have no this issue, not throw handled of exception, the recycle is not needed.
PS: If the asp.net is so bad that needs every now and then a reboot, then I will change language. Of course is not, is very stable and good language that can run for days (if not for ever) if the program is good and well designed. And this is from real life, with real sites, real server - not just theory.
The thread will be started on each Application_Start event.
It will be a monitoring thread which is supposed to run constantly.
So even if the app shuts down, once it is restarted the thread will start too ensuring it runs all the time.
However I need to be sure that this thread will not be stopped / shut down while the application is running.
So in a few words, does anybody know if asp.net could shut down such a thread without actualy stopping / recycling the application.
As a matter of design, you shouldn't depend on asp.net to run threads like this. Little things like app recycling can cause you a lot of trouble.
Instead, create a windows service to execute the thread. This way you don't have to worry about it.
Update
I just wanted to add a little more information.
IIS has the ability to execute your app across multiple threads and processes. A standard site installation usually only has a single process (aka: web garden) assigned which spins up around 20 threads to handle request processing.
However, any IIS administrator can easily add more processes to the mix. They usually do this when a site can hose a single process either because request processing takes too long, or the number of handler threads isn't enough, or as a temporary measure if the app has enough problems that a single thread will hose the entire process fairly often.
If you have a thread being spun on app start, then it will create one for each worker process the site has. This may be unexpected behavior to you or your successors.
Also, monitoring apps are almost always completely separate to the application they are monitoring. One of the primary reasons is that in the event the monitored process dies, hangs, or otherwise becomes unresponsive then the monitoring app itself still needs to carry on and log this information. Otherwise the monitored process could very well hose the monitoring app itself.
So, do yourself a favor and move this to its own process. The best way to do this on an IIS server is to create a windows service and give it the appropriate execution rights to do what you need.
I have a WCF service installed on IIS7. I noticed that the first call to my service is always very very slow. The subsequent calls are much faster & acceptable.
If there are no calls made to the service for some time, it again goes to sleep mode. After this the next call again takes a long long time.
Any remedies for this problem?
It is because of process management on IIS. When there are no calls for certain period of time IIS release the recourses and stops the process.
This is why you can notice that it is slow for first request and for requests after a long delay. Because while the first request or after long period of silence IIS loads everything from scratch. JIT complier runs and etc...
Also note :
When you are hosting WCF services on IIS, the WCF services enjoy all the features of ASP.NET applications. You have to be aware of these features because they can cause unexpected behavior in the services world. One of the major features is application recycling, including application domain recycling and process recycling. Through the IIS Management Console, you can configure different rules when you want the recycling to happen. You can set certain thresholds on memory, on time, and on the amount of processed requests. When IIS recycles a worker process, all the application domains within the worker process will be recycled as well
If you need automatic starting: The Windows Service Control Manager allows you to set the startup type to automatic, so that as soon as Windows starts, the service will be started, without an interactive logon on the machine. So you can use Windows service as a host.
More details you can check in Hosting and Consuming WCF Services.
There is another approach through which you can make it better. We have some kind of scehduled process which keeps hitting our server like every 5 mins with very light 'fetch' requests to keep all servers "hot" (by loading most of the required dlls etc) so that user experience is far better.
I agree it is not a fool proof way but still is something you can consider apart from increasing the recycling settings in IIS.
I have two diffrent web services(running on local machine) and pointing to one application pool(1.Can I do that?Is it any performance concern?).I have not much knowledge about how the applicationpool will works.
the other .Net application is using two webservices,but frequently one webservice is not responding which internally calling by ssis package with in the .Net application.
what might be the reason and how to make sure it responds all the time, is there any better way to improve the performance?
if am missing or any further information, Comments Welcome
Yes you can have multiple web applications using to the same application pool.
Is it a performance concern? If it is really high traffic or is faulty code, then perhaps.
Application pools allow pushing sites to different processes, reducing the risk of each affecting the other. If one app pool contains an application/web application that has a memory leak, the leak will only affect that particular process, at least directly. Each process can be recycled either by time or system parameters, which mitigates risks of having something in a bad state.
Performance? Another benefit to app pools is the ability to have multiple instances running simultaneously (a similar thing when putting each app in its own pool). The benefit of this is that more request can be handled at a time. The down-side is that you cannot use in-process session state and your application state will be duplicated for each instance of the process. You would need to consider how much 'stuff' you keep in session and how your caching scheme would be effected, but, it has potential for giving a web application more scalability.
You mention call SSIS... I am assuming that is a long-running service, so you would probably want to push the call to that process to some sort of queue that can process outside of the web service request. MSMQ might work for you. If using a queue as such, you would initiate the running of the code, then have a way of checking on the status of the call to see if it is done.
I agree with Greg Ogle but one more point I think is worth mentioning. Splitting the applications into multiple app pools will also give you an added benefit when it comes to troubleshooting if there are any issues. If you have the various applications split out, you can tell specifically what app pool is related to what w3wp.exe process in the time of need. Like say when that w3wp.exe process is taking 98% of your cpu.