I am working on windows azure cloud service. First time when i click on login button it takes 6 to 7 seconds but after sometime when i click on same login button it takes 2 seconds. I am not able to understand why it is happening so though the server side code is same for both processing but subsequent calls are quiet faster than first call ?.
"First-hit" delay is very common with ASP.NET applications. There is the overhead of JIT compilation, and various "pools" (database connections, threads, etc) may not be initialized. If you have an ASP.NET Web Forms application, each .aspx page is compiled the first time it is accessed, not when the server starts up. Also the various caching mechanisms (server or client) that make subsequent requests faster are not initialized on that first hit. And on the very first hit, any code in Application_Start will be run, setting up routing tables and doing any other initialization.
There are various things you can do to prevent your users from seeing this delay. The simplest is to write some kind of automated process that hits every page and run it after deploying a new release. There are also modules for IIS that will run code ahead of the Application_Start, when the site is actually deployed. Search for "ASP.NET warmup" to find those.
You may also experience delays after a period of inactivity, if your ASP.NET App Pool is recycled - this resets a bunch of things and causes start-up code to be run again on the next request. You can ameliorate this effect by setting up something to ping a page on your site frequently so that if the app pool is recycled it is warmed up again automatically, instead of on the next actual user request. Using an uptime monitoring service will work for this, or a Scheduled Task within the Azure ecosystem itself.
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I'm currently experiencing some hangs on production environment, and after some investigation I'm seeing a lot of request queued up in the worker process of the Application Pool. The common thing is that every request that is queued for a long time is a web api request, I'm using both MVC and Web API in the app.
The requests are being queued for about 3 hours, when the application pool is recycled they immediately start queueing up.
They are all in ExecuteRequestHandler state
Any ideas for where should I continue digging?
Your requests can be stalled for a number of reasons:
they are waiting on I/O operation e.g database, web service call
they are looping or performing operations on a large data set
cpu intensive operations
some combination of the above
In order to find out what your requests are doing, start by getting the urls of the requests taking a long time.
You can do this in the cmd line as follows
c:\windows\system32\inetsrv\appcmd list requests
If its not obvious from the urls and looking at the code, you need to do a process dump of the w3wp.exe on the server. Once you have a process dump you will need to load it into windbg in order to analyze what's taking up all the cpu cycles. Covering off windbg is pretty big, but here's briefly what you need to do:
load the SOS dll (managed debug extension)
call the !runaway command
to get list of long running threads dive into a long running thread
by selecting it and calling !clrstack command
There are many blogs on using windbg. Here is one example. A great resource on analyzing these types of issues is Tess Ferrandez's blog.
This is a really long shot without having first hand access to your system but try and check the Handler mappings in IIS Manager gui for your WebApi. Compare it with IIS settings of your DEV or any other Env where it works.
IF this isnt the issue then do a comparison of all other IIS settings for that App.
Good luck.
I have an Rest API that is hosted in IIS8. The API is not called very frequently, perhaps 30 times per day. It seems that when the API is called it takes quite a while to get the first result, subsequent calls a short time later return very quickly. It seems that IIS is releasing resources and unloading the API and resources after a period of time.
Is there a way to force IIS to keep API up and active so that every time a request comes it responds quickly?
Couple of ways are mentioned here - Can you prevent your ASP.NET application from shutting down?
Other then that there is Application Initialization module http://iis.net/downloads/microsoft/application-initialization. Application Initialization module makes sure your process is up and running and loaded with all the necessary libraries, however it works only on IIS 7.5 and greater and framework 4.0 and above.
I have a WebAPI application running on Azure WebSites. It is running in Basic mode and I have the option to make it "Always On". There seems to be conflicting information online about what this means exactly. I know the effect, but the "how" matters a lot here. In particular, does something automatically hit an endpoint in my application periodically? If so, can I control the endpoint it hits?
As I mentioned, it is a Web API application and the default route does non-trivial work and results in a notable amount of outbound traffic and it will also result in items being placed onto a work queue that will eventually be processed. I want the application always on (no cold start times) but I don't want some service making requests of application.
As soon as your Azure Website is marked as AlwaysOn, your site root will be hit within a few seconds. We also make sure your site is up and running on all the workers (if you have configured auto scale option or such). After that, if the worker process crashes, alwaysOn makes sure that it comes back up.
You cannot control the endpoint that it hits.
I have a classic ASP application that has been stable for years and now we're having all kinds of problems with it. After moving the app between machines and wiping the original so we could have a fresh install of windows, we've come to the following "symptom". The app pools do not appear to allow for multiple simultaneous requests. Here's what we are seeing:
The app runs normally for most people, but when someone within one of the app pools accesses a long-running script (usually one with lots of DB access) all of the other users in the pool must wait for that script to complete. Once the script completes, everyone else's requests run. This initially made us suspect the DB connection string or something.
UNTIL... we noticed also that large file uploads into our system also cause the app pool to stop responding. What's interesting about this is that we're using the SAFileup COM+ object to do our uploads, which has a progress display in a pop-up window. When you go to upload the file, the progress display comes up, but then never refreshes to show upload progress. If you wait it out, however, the file will eventually upload and the other pending requests will process as normal.
Our app pools are in the default configuration, using the IWAM account to launch. I checked to ensure that the IWAM account has all the appropriate permissions. It does.
We've tried a variety of DB connection strings, none solved the problem (though I'm thinking it's not the DB connection string). Just in case someone thinks it is, here's our connection string: "Provider=SQLNCLI;Trusted_Connection=yes;Server=(local);Database=demo;". It couldn't be simpler. This string was previously not a problem.
I fussed with the web gardens thing and it does, indeed, make the system respond to multiple requests, but each worker thread in the garden has its own session state which causes our users to get booted when their request gets randomly assigned to a new worker thread. Only having a single worker process in the garden was never an issue before anyway.
I've used SQL Profiler and sp_who2 to see if during the long-running scripts there are any deadlocks or blocks on the SQL Server. There are not.
The issues initially started after we had installed some patches from Microsoft. We wiped a machine clean and installed Win2k3 server, then SP2, and then didn't patch anymore after that. The problem remained, so it doesn't appear to have been a patch.
I'm pretty much at a loss now... does anyone have any experience with similar issues? If so, how were they fixed?
Check that you don't have ASP debugging enabled on the server. This will force the ASP script engine to run on a single thread.
Sounds like an limit on the number of concurrent incoming requests to the IIS or the Windows Server..
Check out http://blogs.msdn.com/b/david.wang/archive/2006/04/12/howto-maximize-the-number-of-concurrent-connections-to-iis6.aspx and http://forums.iis.net/p/1152112/1880908.aspx#1880908 on how to tweak the settings.
I have a web application that's consuming a WCF service. Both are slow on warmup after IIS reset or app pool recycle. So, as a possiible solution I installed Application Warm-Up for IIS 7.5 and set it up for both web site and wcf service.
My concern is, it doesn't seem to make any difference - first time I hit the site it still takes long time to bring it up. I checked event logs, there are no errors. So I'm wondering if anything special needs to be done for that module to work.
In IIS manager, when you go into the site, then into Application Warm-Up, the right-hand side has an "Actions" pane. I think you need the following two things:
Click Add Request and add at least one URL, e.g. /YourService.svc
Click Settings, and check "Start Application Pool 'your pool' when service started"
Do you have both of these? If you don't have the second setting checked, then I think the warmup won't happen until a user hits the site (which probably defeats the purpose of the warmup module in your case).
There is a new module from Microsoft that is part of IIS 8.0 that supercedes the previous warm-up module. This Application Initialization Module for IIS 7.5 is available a separate download.
The module will create a warm-up phase where you can specify a number of requests that must complete before the server starts accepting requests. Most importantly it will provide overlapping processes so that the user will not be served by the newly started process before it is ready.
I have answered a similar question with more details at How to warm up an ASP.NET MVC application on IIS 7.5?.
After you have fixed possible software/code optimizations allow me to suggest that each and evey code needs processing via hardware cpu. And our server skyrocketed in performance when we went to a multicore cpu and installed more GIGS of ram and connected UTP-6 cable insetad of standard UTP 5e cable onto the server... That doesnt fix your problem but if you are obsessed with speed as much as us, then you will be interested in the various dimensions that bottleneck speed.