I have a C# Windows Service running in approximately 500 locations. When the services start they initiate a connection with a remote SignalR hub running on a VM in AWS. The connection/tunnel is then used for sending information from the server to each location throughout the day.
This has been running fine for the past 18 months, but for the past week the remote services have been losing connection and have to be restarted to reinitiate the connection with the server. I'm using SignalR 2.4.1 which doesn't have the auto reconnection feature of the newer versions.
I've noticed that it seems to be happening about every 18 hours. Nothing has changed on the clients or on the server that anyone is aware of.
I'm looking for ideas on what could be causing this. Any input would be appreciated.
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One of my customers suddenly reported that a local website I've made in Server-side Blazor only can have 4 concurrent connections. When the 5th connection is established, one of the other 4 is getting disconnected.
I Have looked through my configuration and can't see any sign of this. Connections is not limited in IIS configuration.
OS: Windows Server 2016
I have tried to debug at my local copy of the virtual machine, but here everything is working as expected.
Anyone who got a clue what I can look for?
I have a SQL Server with two databases, a production database and a development database. The .net 2.0 website hitting the production database with manual SqlConnection code is working fine. The other database is being hit from a newer ASP.NET MVC app using Entity Framework 6.2 and is getting timeout issues. The timeout takes 30 seconds the first time, but the page comes back almost instantaneously on subsequent refreshes. Both websites are on the same box as the database, so are only using "localhost" to connect. They are using SQL Server user logins, not Windows authentication.
I copied the .edmx and .tt files into a .net console app and that app has no problem hitting the database with the exact same linq query and pulling the same data that is failing.
I then created a new web site and copied just that same code into an aspx page. It fails the first time with a timeout, and then works on subsequent attempts (and a week ago, the main dev site was doing the same thing).
I separated the dev database from the SQL Server 2008 R2 server and attached it to a newly installed instance of SQL Server Express on a different port, and get the same results.
The web server is windows server 2008 standard 32-bit. I copied both websites and the console application to a new box (I thought was 2016, but it turns out it is 2008 standard 64-bit) and get the same results.
The dev site was working up until a couple of months ago. The client was using local user accounts for everything, but had a domain and wanted to do testing with windows authentication for an old vb app that hits the same database, and I had started migrating testing accounts to the domain. When the client tried to later, for an unrelated reason, change his password, we discovered that he was already using a domain account, but that his laptop could not connect to the domain. We found several other computers that could not connect, even though the machines I had connected to the domain during my testing were working fine. An outside network "friend" was brought in to figure out what was going on. At that point, I lost all track of what was actually done. I know that different network and domain configurations were tried and didn't fix the domain issues, but I don't know what. However, the production site was never rendered inoperative.
I have no idea what is going on. Does anyone else?
Oh, and in case it was a provider issue, I've also tried manual connection using OleDbconnection from the web app, and it also fails with the Timeout issue.
Update:
I spun up a new DataCenter 2016 box, installed IIS and .net on it and copied the website to that box. It has no problems hitting the database and pulling the data from the other server.
I know patches and such were updated on the original box while the domain and network were being manipulated, but I don't know how far behind they were. I suspect that some patch changed some default or inherited .net configuration options or something. I did do a "repair" on the .net installation, and that didn't make a difference. However, with the production site working fine, I'm not currently willing to uninstall .net or anything else. I'm afraid I would risk pushing this same error into the production site and the client would be screwed.
It seems that for some reason, the timeout period elapsed while attempting to consume the pre-login handshake acknowledgement.
Try increasing the connect timeout property in your connection string to 60 or more. Default is 15 (in seconds).
Example: Data Source=(LocalDB)\v11.0;Integrated Security=True;Connect Timeout=30
I have a ASP.net Web API deployed on azure and I also have there a MySql database in separate virtual machine running on linux. The problem I have is that when I restart the database and redeploy the web API from visual studio the connection between web API and mySql is working fine but after like 30 minutes I get this error:
"Unable to connect to any of the specified MySQL hosts"
If I want to make it work again i have to restart the virtual machine with database and redeploy the web API from visual studio. I am using connection string like this to connect in my web config
<add name="DefaultConnection" connectionString="Server=publicIpAddress;Port=3306;Database=db_12345_db;Uid=user;Pwd=*********;" providerName="MySql.Data.MySqlClient" />
This connection was working on server we had before we switched to azure. I suspect I did not configure azure correctly.
Any idea how to fix this issue ? Thanks
Connections Dropped
When connecting to a Azure SQL Database, idle connections may be terminated by a network component (such as a firewall) after a period of inactivity. There are two types of idle connections, in this context:
Idle at the TCP layer, where connections can be dropped by any number
of network devices.
Idle by the SQL Azure Gateway, where TCP keepalive messsages might be occurring (making the connection not idle from a TCP perspective), but not had an active query in 30 minutes. In this scenario, the Gateway will determine that the TDS connection is idle at 30 minutes and terminate the connection.
https://github.com/sidorares/node-mysql2/issues/316
Hope this works for you.
I have a c# app that exports data from the database to the user's Exchange Calendar, using Microsoft.Exchange.WebServices (15.0.0.0). My app is DotNet 4.5.2 and I use Visual Studio 2013.
The app has been working fine for a year, and even now works 95% of the time. The app runs constantly on machine that I am logged into and monitor. This is a low volume process, perhaps 50 items get exported per day at most.
Every couple of days, the program will give this error:
"The request failed. Unable to connect to the remote server"
when the app is attempting to create an EWS connection to the server.
It will do this for maybe 10-20 items. So I shut it down, run it again, and it works perfectly fine on all the records that failed before.
This is my first EWS app, but I've been programming 30+ years and do have somewhat little knowledge of internet based apps.
Any helpful information or suggestions would be greatly appreciated!
Thank you kind people!
The internet often works, but should never be considered reliable. Anything using it should handle errors, and retry if desired. The classic approach is Exponential backoff. Its possible something nasty is going on, like your ISP swapped your IP address, or just intermittent failure. I don't know anything EWS specific, but there may also be sources of flaky issues there as well.
I am trying to solve the problem of very long response times from MySQL when opening a connection using the MySQL Connector for .net.
I have installed MySQL 5.5 running on an Azure VM (Server 2008) with --skip-name-resolve, and the database user accounts' host restrictions are using IP addresses. I am using the latest MySQL Connector for .net in my WCF service running on Azure (in the same location US- East, I have been using a trial subscription, no affinity set). My connection string in the WCF service is using the internal IP address of the VM hosting MySQL as the server parameter value. I also have "pooling = true;Min Pool Size=2;" just in case (I have tried without these parameters too).
When tracing the WCF the query response time once the service is running and processing requests are pretty good (even where each query result is unique and so not being cached) and I have no issues with the performance of MySQL providing it's getting hit frequently.
But the huge problem I haven't been able to crack is the length time it takes to get the connection to MySQL Open after no calls to the database have been made for about 3 or 4 minutes. If no database calls are made for a few minutes it takes 8 or 9 seconds or more to open the connection again. I wrapped the actual "conn.open();" with trace statements before and after calling, and this is the behaviour I am seeing logged time and time again after a few minutes of inactivity.
Incidentally, I have also tried (and still am using) the 'using' style of connection handling to ensure that the MySQL Connector is managing the connection pool.
e.g.:
using (var conn = new MySqlConnection(Properties.Settings.Default.someConnectionString)) { ... statements ..}
I feel like I have reached a dead end on this one so any suggestions would be greatly appreciated.
I can explain your question "the length time it takes to get the connection to MySQL Open after no calls to the database have been made for about 3 or 4 minutes. If no database calls are made for a few minutes it takes 8 or 9 seconds or more to open the connection again." why it happens:
The Windows Azure websites uses concept of hot (active) and cold (inactive) sites in which if a websites has no active connection the site goes it cold state means the host IIS process exits. When a new connection is made to that websites it takes a few seconds to get the site ready and working. While you have MySQL backend associated to this website, it take a few more seconds longer to get the requested served as there is some time taken by IIS host process to get started. That is the reason after few minutes of in activity the the response time is longer.
You can see the following presentation for more details on Windows Azure Hot (active) and Cold (inactive) Websites:
http://video.ch9.ms/teched/2012/na/AZR305.pptx
As this time, I am not sure and do not know how you can keep the websites always hot, even if moving to shared website or it is not possible at all. What I can suggest you to write your issue to Windows Azure WebSites Forum and someone from that team will provide you an appropriate answer.