I have an application where it seems that for different users there is a different timeout and for some users the timeout is too soon.
It is a C#/.NET application that runs an ASPX based Website. Basically, you fill out a form and click on submit and then must wait a few minutes and you get the results. When I am connected to the system and perform this action it takes around nine minutes and I see the results.
But if another user performs this action after five minutes he gets displayed a “This page can’t be displayed” message in is browser (internet explorer – the rest of the message is “Make sure the web address http:// … is correct, Look for the page with bing, Refresh the page in a few minutes”).
A little more background:
First the nine minutes seem long, but there is a huge amount of data (collection of datapoints over a span of a year) that is processed and displayed, and basically it works, so I don’t think it is necessary to discuss this point. For a lesser amount of data there are no problems.
The data from the database is obtained via C# and it performs the queries to a MS SQL database.
First I thought it would help to set in the web.config in the httpRuntime tag the executionTimeout attribute. But the compilation tag has the debug flag set to true (and the application is deployed as release via visual studio on the server) – so the debug flag (as far I understand) overrides the executionTimeout anyways.
The Server on which the application is running is Windows Server 2012 R2 and for the site I also set under IIS in the advanced settings in the behavior / limits area the connection timeout on a higher value. But this hasn’t any effect.
I think I am missing some point, because as far I understand the deployed application doesn’t have any timeouts set (because of the debug flag) and this behavior seems user specific.
Do you have any hints or ideas where I can look for?
Edit
In the comments was suggested to check the SQL Server logs for errors, the log was error free.
As it turned out, it was a problem due to an older version of the browser that had some strict timeout settings. By switching to another version, this behavior doesn't show anymore.
Related
I have an blazor server-side app deployed on average 100 site which generally works pretty well.
But for very few site, end-users complain about micro disconnection/reconnection on the app (they see the components-reconnect-modal few seconds).
I logged some information on the OnConnectionUpAsync and OnConnectionDownAsync of the CircuitHandler to see whats happen, and effectively i notice some log showing a lot of time client disconnected for one, two or three seconds. But i don't have the reason
There is an average of maybe 50 and 100 end user connected at the same time at the app on this site.
I really don't know how to start to investigate this case. This client have a server well dimensionnate, with recent windows server, the configuration is OK.
I don't have specific configuration or parameters on the app
I would suspect the problem is on the network of my client (so not specific on my app, like shutdown of the network for 3 second), but The client assure me is network works very well and he don't have any problems with his others apps.
Have you any idea what i can do to have more information on this problem ?
do you know some tools which can test the network and show potentials problems ?
thanks in advance
I've been trying to diagnose an issue pertaining to thousands of hung/stuck EndRequest requests in IIS. This is becoming a large problem for us as we're hitting the concurrent connection cap after about a week or two and have to recycle the whole application pool to clear the request list.
Because this is a live application, I have limited troubleshooting options, so anything that would halt or bring down the application pool I am not allowed to do.
IIS Information
Concurrent connection cap is set to its maximum of 65535.
Configuration debug in the web config is set to false and we have a
timeout set at 110 seconds.
Windows Server 2012 R2 Version 6.2 (Build 9200)
IIS Version 8.5.9600.16384
The long running requests have 0 data transfer, checked with
WireShark.
I'm pretty much at a loss on why these aren't timing out. I've set all the appropriate settings - the ones I could find from MSDN and other sources. We have a very, very hard time replicating this on our development environment so it's been blind testing for the most part. I've found articles and such on other state hangs, but I cannnot find anything on why a request in the EndRequest state will not time out.
Advanced Settings Page:
https://postimg.org/image/gxec32kmt/
Application Pool Requests Page:
https://postimg.org/image/qupcw57o5/
Web Config:
https://postimg.org/image/5xt4rh1xh/
Update 1
I did a bit of digging into our fallback that is supposed to close connections after an hour of no usage. We seem to currently have 10,153 sessions still active with a last active time of 3 days ago. I've stepped through this function quite a bit and it seems to be working as intended. It goes through the list of sessions and anyone over an hour of inactivity has their WebSocketHandler.Close() method called. However it seems some sessions are refusing to close after the method is being called. We have logging in place to tell us if any exceptions are being thrown during the run but it seems as though it's running as expected.
This was my mistake. I was running against an old sessions data pull. A current pull of the session data shows no sessions running greater then their specified time. This means that the WebSocketHandler.Close() was called on them and they were removed from our in-memory list.
Update 2
NETSTAT using netstat -s on pastebin: https://pastebin.com/embed_js/qBbZ4gJ1
Update 3
Correction to update 1. Can a connection close be called and fail? If so, then we're accidentally orphaning the reference to the connection in our server. I would still expect the IIS timeout to kick in however, there must be some catches to it collecting requests.
Very very strange issue here... Apologies in advance for the wall of text.
We have a suite of applications running on an EC2 instance, all connecting to an RDS instance.
We are hosting the staging and production applications on the same EC2 server.
With one of the applications, as soon as the staging app is moved to prod, over 250 or so connections to the DB are opened, causing the RDS instance to max out CPU usage and make the entire suite slow down. The staging application itself does not have this issue.
The issue can be replicated by both deploying the app via our Octopus setup, and also physically copy pasting the BIN/Views folder from staging to live.
The connections are instant, boosting the CPU usage to 99% in less than a minute.
Things to note...
Running how to see active SQL Server connections? will show the bulk connections, none of which have a LoginName.
Resource monitor on the FE server will list the connections, all coming from a IIS, seemingly scanning all outbound ports, attempting to connect to the DB server on its port. FE server address and DB server address blacked out respectively. Only a snippet of all all of the connections.
The app needs users to log in to perform 99.9% of tasks. There is a public "Forgot your password" method that was updated to accept either a username or password. No change to the form structure or form action URL, just an extra check in the back.
Other changes were around how data was to be displayed and payment restrictions under certain conditions. Both of which require a login.
Things I've tried...
New app pools
Just giving it a few days to forget this ever happened
Not using Octopus to publish
Checking all areas that were updated between versions to see if a connection was not closed properly.
Really at a loss as to what is happening. This is the first time that I've seen something like this. Especially strange that staging is fine, but the same app on another URL/Connection string fails so badly.
The only think I can think of would potentially be some kind of scraper that is polling the public form, but that makes no sense as why isn't it happening with the current app...
Is there something in AWS that can monitor the calls that are being made? I vaguely remember something in NewRelic being able to do so.
Any suggestions and/or similar experiences are welcomed.
Edits.
Nothing outstanding in logs for the day of the issue (yesterday)
No incoming traffic to match all of the outbound requests
No initialisation is performed by the application on startup
Update...
We use ADO for most of our queries. A query was updated to get data from different tables. The method name and parameters were not changed, just the body of the query. If I use sys.dm_exec_sql_text to see what is getting sent to the DB, I can see that is IS the updated query that is being sent in each of the hundreds of connections. They are all showing as suspended though... Nothing has changed in regards to how that query is sent to the server, just the body of the query itself...
So, one of the other queries that was published in the update broke it. We reverted only that query and deployed a new version, and it is fine.
Strangely enough, it's one that is being run in one form or another over the entire suite. But just died under any sort of load that wasn't staging, which is why I assumed it would be the last place to look.
This question is really around analysis - how do I analyze what's causing the problem?
Situation - we have a C# webservice configured through IIS 7.5, and a website in the same intranet domain hitting the webservice with POST and GET methods. Server is windows 2008 r2 64-bit, C# is 4.0. The first call of the day is slow (30-60 seconds), though I have not checked if I try again later in the day is it slow as well. Subsequent calls are 2-3 seconds. When checked using FireFox web console or firebug, the time is spent on "Waiting" for the webservice.
Things I've tried :-
Setting no recycle time for the webservice AppPool
Setting no idle time-out for the webservice AppPool
Setting proxy bypassonlocal = true and usesystemdefault = false in case it's a proxy look up issue
Nothing's worked so far. My thought is that even if it's C# compile to machine code on first run, it shouldn't 'expire' if the AppPool does not time-out or recycle, yet it is slow everyday.
So flat out of options, how do I go about trying to find the source of the problem? Any diagnostics I can run on the server to check what the webservice is doing?
From your description it sounds as if your webservice might be going to sleep given the first call after a period of inactivity is slow and subsequent calls are faster.
I've seen this behaviour occur on many of my .NET IIS applications, can be frustrating to say the least!
This is however, default .NET behaviour, but there are ways of keeping your application awake, especially as of .NET4.
I refer you to the following article as a first step. Give it a go and see if this makes any difference for you:
https://www.simple-talk.com/blogs/2013/03/05/speeding-up-your-application-with-the-iis-auto-start-feature/
Good luck!
(Sorry if this is a really long question, it said to be specific)
The company I work for has a number of sites, which have been running for some time with no problems. The applications are a mix of ASP.NET 2.0, 3.5, and 4.0, all using an ADO.NET to connect to a SQL Server Standard instance (on the same webserver) all being hosted with IIS7.
The problem began when we moved to an upgraded webserver. We made every effort to set up the server, db instance and IIS with the exact same settings (except for the different machine name, and the fact that we had upgraded from SQLExpress to Standard), and as far as we could tell, we did. Both servers are running Windows Server 2008 R2 (all current updates applied), and received a default install.
The problem is very apparent when starting up one of these applications. When you reach the login page of our application, the page itself loads extremely fast. This is true even when you load the page from a new machine that could not possibly have the page cached, with IIS caching disabled. The problem is actually visible when you enter your login information and click the login button. Because of the (not great)design of our databases, the login process must access a number of databases, theoretically up to 150 separate DBs, but in practice usually 2. The problem occurs even when only 2 databases (the minimum) are opened. Not a great design, but we have to live with it for now.
When trying to initially open a connection to the database, the entire process stops for about 20 seconds every time, regardless of whether you are connecting to 2 dbs or 40. I have run a .NET profiler (jetbrains dottrace) against the process, and the only information I could take from it was that one or all of the calls to sqlconnection.open() was accounting for 90% of the time. This only happens on first-use of the application, but the problem is compounded by the fact that IIS seems to disregard the recycling settings we have set for it, and recycles the application after a few minutes of idle, causing the problem to occur again.
I also tried to use the SQL Server profiler to see which database operations were the cause of the slowdown, but because of all the other DB activity, (and the fact that I had to do this on our production server, because the problem doesnt occur in our test environments) I couldn't pin down the exact operation that was causing the stoppage. I will try coming in late at night and shutting down the production sites to run the SQL profiler, but I might not be able to do this right away.
In the course of researching the problem, I have tried a couple solutions
Thinking it might be a name resolution problem, I tried modifiying both the hosts file on the webserver as well as giving the connectionstrings an IP address instead of the servername to resolve, with no difference. I have heard of the LLMNR protocol causing problems like this, but I think trying to connect by IP or resolving with the hosts file should have eliminated that possibility, tho i admit I never tried actually turning off LLMNR.
I have increased the idle timeouts, recycling intervals etc in IIS, but this doesn't even seem to be respected, much less solving the problem. This leads me to believe there is a setting overriding the IIS application settings on the machine.
multiple other code fixes, none of which made any difference. Is a SqlServer setting causing the problem?
other stuff that i forgot by now.
Any ideas, experience or whatevers would be greatly appreciated in helping me solve this problem!
I would advise using a non-tcp connection if you are still running the SQL instance on the local machine. SQL Server supports several protocols, tcp, named pipes, and shared memory are the more common.
Named Pipes
Data Source=np:computer\instance
Shared Memory
Data Source=lpc:computer\instance
Personally I prefer the Shared Memory. Remember you need to enable these protocols, and to avoid configuration mistakes I suggest you disable all you are not using.
see http://msdn.microsoft.com/en-us/library/ms187892.aspx
IIS Reset
In IIS7 there are two ways to configure the idle-timeout. Both begin by clicking on the "Application Pools" section and right-clicking the appropriate app domain. If you click the "Recycling..." option there is one setting. The other is in "Advanced Settings..." under the section for "Process Model" you will find "Idle Time-out (minutes)" which set to zero disables the process timeout. This later option is the one that works for us.
If I were you I'd solve this problem first as restarting the appdomain and/or worker process is always painful even if you don't have a 20 second lag.
Some ideas:
from the web server, can you ping the db server and get a "normal"
response, or are you seeing a similar delay?
if you're seeing a delay, run a tracert to see if you can nail down where the slowness is occurring
try using a tool like QueryExpress (http://www.albahari.com/queryexpress.aspx) which doesn't require an install to run. You can download this EXE and run it from your web server. See if you can connect to your db using this and run queries in a normal fashion.
Try something like SysInternals' TcpView (http://technet.microsoft.com/en-us/sysinternals/bb897437) to take a look at your open connections and see what activity is happening on your server and how much data is being sent to and received from your db server.
Just some initial thoughts on where I'd start to look based upon your problem description. I hope this helps. Good luck with things!
With IIS not respecting recycling settings: did restarting IIS/rebooting change the behavior?