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.
Related
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.
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.
This should be a simple question but I haven't managed to find the answer on google.
I would like to know, in terms an idiot can understand, exactly what application lifetime means in ASP.NET (and therefore when you can expect application start and end events to run).
I assumed it would be when you run and stop the app in IIS, but I've read things that suggest it's related to number of requests.
By default the lifetime starts with the first request to the app. And it ends after an idle timeout.
But this is configurable based on various things (including request count) in IIS.
And IIS7.5 has the ability to start an application when IIS starts, rather than waiting for the first request.
You do have to consider how the Application Pool that your site is running in is configured. Applications can be dumped in a pool with other apps or it can have its own. The pool can be restarted based on memory usage beyond a certain point, by a timer so to speak (reset daily at 3am for example) and I believe by a number of requests beyond a certain configurable number. Not a super expert on IIS so verify before you buy ;-)
After deploying an ASP.Net application to a new server, the first user to hit the app gets a long pause, presumably because the app is performing its initial compilation. However, this pause seems to also also occur after the application has timed out and unloaded itself from memory.
The first compilation would be tolerable as it only happpens once, but the 2nd one seems to me like it should be unnecessary....is there a workaround to address this issue? It would be nice to be able to extend the application timeout, but I only see a way to extend the session timeout, which I would rather not do, as this would keep all user sessions in memory for a long period of time.
That's IIS shutting down the worker process - the default is a 20 min idle time. In IIS6, you can configure the app pool and turn off the Idle timeout (on Performance tab). In IIS7, it's in the Advanced Settings.
A common way (though looks hackish to me) to keep the worker process alive is to have some program issue web requests to some URL in the application on a regular basis.
You can reduce the initial startup time by precompiling the ASP.NET app with aspnet_compiler.exe. This won't reduce the initial request time to zero (it'll still need to create the worker process and do other housekeeping.) but it'll noticeably reduce it.
I did find some recommended settings for the App Pools in IIS. The intended outcome of these settings is to reduce the number of times your application needs to go through the startup cycle. These settings should apply to IIS 6 as well as IIS 7:
Recycle Worker Process: Disable. Use this only if you have multiple websites and are trying to isolate processes.
Shutdown worker processes after being idle for (time in minutes): Disable unless you are sharing resources on your server. With this setting disabled, your website should not unload, ensuring that startup time for your site is as minimal as possible.