First of all, I have been started to studying the C# from 6 months ago and I'm not good at English.
So I'm sorry if I say something that you cannot understand.
Now, I'm developing the application with C# that ONLY connect to MySQL server(both of remote and local).
And I use a MySql.Data.Client package, it's version 8.0.12.
This ONLY means "I don't send any queries. I want to find that I can connect to server using a UserName and Password.".
Then, I wrote this code. And I have two questions, and I want to get any advises.
sendCommand = string.Format("host={0}; userid={1}; password={2}; SslMode=none;", pIPAddress.ToString(), mOption1, mOption2);
MySqlConnection mysqlConnention = new MySqlConnection(sendCommand);
mysqlConnention.Open();
if (mysqlConnention.State.ToString() == "Open")
{
result = true;
}
mysqlConnention.Close();
Q1
The application should not send unnecessary packets to server.
However I found it from WireShark and it's "show variable" command.
I tried to change some properties about ConnectionString(in this code, it's called "send Command") because I want not to send "show variable" command. (for example, ChacheServerProperties=true, AllowBatch=false, and so on...)
Can I connect without "show variable" command?
Q2
(It's soloved but I cannot find the causion)
When I started developing this application, I used MySql.Data.Client 8.0.11.
But in that time, the MySqlConnection.Open Method was taken a long time for connection to server.(It was about 7~10 second.)
The network problems was none, and I was able to connect using cmd.exe without a long time.(It was not taken a second.)
I tried any patterns, changed server to connect, restarted OS(both of the application side and server side), changed ConnectionString properties).
MySQL server was not dying and It looked like the cause is not in MySQL server and network.(Getting the application "ServerGreeting" packet from server was no time but next action that the application send "LoginRequest" packet to server was taken a long time.)
However I was not able to slove this problem. But I updeted MySql.Data.Client version to 8.0.12, I can slove!
Is this problem caused by MySql.Data.Client 8.0.11?
And have I any solution?
The application should not send unnecessary packets to server. … Can I connect without "show variable" command?
You can, by using an alternative ADO.NET library: MySqlConnector. It sends a lot fewer packets when opening the connection (but it may not send the absolute minimum possible).
But in that time, the MySqlConnection.Open Method was taken a long time for connection to server.(It was about 7~10 second.) … Is this problem caused by MySql.Data.Client 8.0.11?
This sounds very much like MySQL bug 80030, which is a bug in 8.0.11. That case says it's going to be fixed in 8.0.13, not 8.0.12, but perhaps Oracle changed their release plans after making that comment.
This could also be fixed by using MySqlConnector, which never used an inefficient WMI query that was causing the performance problem in MySql.Data.
Related
I wrote an application that runs on Linux and uses ntpdate to query our NTP server. In some cases, ntpdate returns the error "no server suitable for synchronization found”.
I need to be able to detect the same error on our Windows application. How can i achieve that using C# (my goal is to “fail” where ntpdate fails in order to align the behavior of my 2 applications)?
Found “How to Query an NTP Server using C#?”, but unfortunately it returns the time where ntpdate returns "no server suitable for synchronization found”.
Also tried using windows commands:
“w32tm /monitor /computers:ntp_server_ip”
And
“w32tm /stripchart /computer:ntp_server_ip /dataonly /samples:1”
But i failed to understand from its output that there is an issue with the NTP server.
I have spent quite some time looking for an answer, but with no success.
Please assist.
I have a WebAPI service which connects to an Oracle database using Oracle.ManagedDataAccess.dll. Each time after a reset of the application pool (or a deployment) there is a long delay on the first OracleConnection.Open() statement. It's typically around 8 seconds. Subsequent calls are around ~0.5 seconds each.
After reading lots of suggestions regarding server OS and networking issues, i have narrowed it down to the oracle client itself. If I remote debug my code, set a breakpoint on the open statement, and then run Sysinternals Process Monitor i can confirm that the first open statement produces 544 entries, second and subsequent tests produce 2 entries.
The entries are quite random, but mostly relate to Cryptography. A quick overview of the logs:
RegOpenKey, HKLM\SOFTWARE\Microsoft\Cryptography\Defaults\Provider Types\Type 001
RegOpenKey, HKLM\SOFTWARE\Microsoft\Cryptography\Defaults\Provider\Microsoft Strong Cryptographic Provider
RegSetInfoKey, HKLM\SOFTWARE\Microsoft\Bryptography\MachineGuid
These are repeated several times, then there are sections like below:
RegQueryValue, HKLM\System\CurrentControlSet\WinSock2\Parameters\Protocol_Catalog9
RegCreateKey, HKLM\System\CurrentControlSet\Services\Tcpip\Parameters
RegCreateKey, HKLM\System\CurrentControlSet\Services\DnsCache\Parameters
RegOpenKey, HKLM\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient
Then there are several reads of the machine.config file followed by multiple TCP connect and receive to the oracle port 1521. Following this is a section reading the time zone from the registry.
My question is, why is the oracle client doing all of this at first open? Is there any way i can predetermine the answer to some of these questions? (like configure the time zone so it doesn't have to 'ask' Oracle for it)?
Only time I have seen something like this was when the address in the tns connect descriptor was not fully qualified, ie host=computername, instead of host=computername.domain.com.
Issue is likely dns resolution as it goes thru suffixes. I imagine you could put in an ip and eliminate dns altogether as a test. Consider posting your tns entry and connection string as well.
FYI, a lot of things are happening when that first connection is created, ie the pool is established and connections are actually opened vs just fetched from the pool, initial parameters for self-tuning are initialized, etc, so i think number of reg reads is probably a red hearing.
We migrated some piece of old software to a new server. We used SQL Server 2008 Enterprise in the past and now we are using SQL Server 2014 Enterprise on a new machine, so it should be faster now.
The old software is legacy software and about to expire, therefore I don't want to put much effort in fixing it. But for some reason there is a C# function running a SQL query against the database for which I get the error message
Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
All I read about that is, that I have to extend the timeout time by using CommandTimeout. But unfortunately everything runs under "context connection = true". Therefore, it would take quite a bit work to rebuild this function with an opportunity to change the timeout.
And I'm asking myself, why did this run on the old machine and way it won't on the new one. So it has to do something about the new machine or the new SQL Server engine. Is there any way to change the standard timeout of 30 seconds for a command in the .NET Framework or in the SQL Server?
Thanks a lot for any suggestions!
You can set the timeout of a command with the CommandTimeout property:
var cmd = new SqlCommand { CommandTimeout = 60 }
Ok, I didn't find a sollution for the problem, yet, but the timeout is not really the source of the problem. I gained access to the old system and run some tests and it turned out that the same function on the old machine with the old server software runs a lot faster, such that there is no timeout.
Hence, I have to focus on server speed and database tuning.
Thanks to everyone who occupied himself with this question!
Edit:
I found a solution to my problem, indirectly. I couldn't find out, why the execution of the statement on the new machine takes so long. But it turned out that the statement itselft uses table variables. I changed them to a local temporary table in the database tempdb. Now the execution takes less than one second instead of more than 7 minutes!
For me, it looks like a problem with some cache or a miss-configured SQL server. Unfortunately, I'm not really the server administrator and I will not twiddle with it. But I will mention it to the administrators. At least, the program runs now perfectly.
I am working with a program that is meant to publish to and read from an existing TIBCO EMS hosted on a server separate from the program. I have referenced the sample code provided with the TIBCO installation, resulting in a big chunk of the program. Here is the code snippet that I am having troubles with:
1 QueueConnectionFactory factory = new TIBCO.EMS.QueueConnectionFactory(serverUrl);
2 QueueConnection connection = factory.CreateQueueConnection(username,password);
3 QueueSession session = connection.CreateQueueSession(false, Session.AUTO_ACKNOWLEDGE);
When line 1 runs, it goes through alright. When line 2 runs, it goes through alright, however, the connection object is null, resulting in an error during line 3 where a NullReferenceException occurs.
I would have at least expected that line 2 would return some sort of error to show that the request timed out, the credentials were wrong, the url is inaccessible, or at least something to let me know what the issue is, but there is nothing like that, until it hits line 3.
Does it have to do with the configuration of my application? All I have done to get this working is include the TIBCO.EMS.dll as a reference and worked with the code from there.
Could it have something to do with the fact that I am connected to a VPN that requires a proxy? If so, how can I set up that proxy in my code?
Any help would be greatly appreciated. Thank you.
The issue was that I was using the wrong version of the .NET framework to work with the Tibco integration. The version I was using was farther along than the original.
It would think that your server URL is incorrect.
try different urls maybe like tcp://localhost:7222 (where localhost can be the IP/Name of the remote server)
install EMS locally on you workstation and see if you can connect to it. (Default admin with no password)
I have run into a frustrating issue which I originally thought was a connection leak but that does not seem to be the case. The secnario is this: the data access for this application is using the Enterprise Libraries (v4) from Microsoft. All data access calls are wrapped in using statements such as
using (DbCommand dbCommand = db.GetStoredProcCommand("sproc"))
{
db.AddInParameter(dbCommand, "MaxReturn", DbType.Int32, MaxReturn);
...more code
}
Now the index of this application makes 8 calls to the database to load everything and I can bring the application to its knees by refreshing the index about 15 times. It seems that when the the database reaches 113 connections is when I recieve this error. Here is what makes this weird:
I have run similar code with the entlib on high traffic sites and have NEVER had this problem ever.
If I kill all the connections to the database and get the production application back up and running everytime I refresh the application I can run this SQL
SELECT DB_NAME(dbid) as 'Database Name',
COUNT(dbid) as 'Total Connections'
FROM sys.sysprocesses WITH (nolock)
WHERE dbid > 0
GROUP BY dbid
I can see the number of connections actively increasing with each page refresh. Running the same code on my local box with the same connection string does not cause this problem. Further if the production website is down I can fire up the site via Visual Studio and run it fine and the only difference between the two is that the production site has Windows authentication turned on and my local copy doesn't. Turning windows authentication off seems to have no effect on the server.
I have absolutely no clue what is causing this or why the connections are not being disposed of in SQL Server. The EntLib objects do no explose .Close() methods for anything so I can't explictily close the object.
Any thoughts?
Thanks!
Edit
Wow I just noticed that I never actually posted the error message. Oy. The actual connection error is: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.
Check that the stored procedure you are executing is not running into a row or table lock. Also if you can possibly try to deploy in another server and check if the application would crawl again.
Also try to increase the maximum allowed connections for your SQL server.
think the “Timeout Expired” error is a general issue and may have seveal causes. Increasing the TimeOut can solve some of them but not all.
You may also refer to the following links to troubleshoot and fix the error
http://techielion.blogspot.com/2007/01/error-timeout-expired-timeout-period.html
Could it be a configuration issue on the server?
How do you make a connection to the database on the production server?
That might be an area worth looking into.
While I don't know the answer I can suggest that for some reason connections are not being closed by you application when run in production. (Stating the obvious)
You might want examine your network configuration between the web server and sql server. High latency networks can cause connections not being closed in time.
Also it might help looking at the performance counters listed in the end of the following msdn article:
http://msdn.microsoft.com/en-us/library/8xx3tyca%28VS.71%29.aspx
Finally, if nothing else helps, I'd get debugger and Enterprise Library source code on production and debug your code inside the enterprise library to find out why connections are not being closed.
Silly question are you properly closing your DataReader? If not this could be the problem and the difference in behaviour between dev and prod can be caused by different garbage collection patterns.
I would disable connection pooling and try to suppress it (heh). Just add ";Pooling=false" to your connection string.
Or, perhaps you could add something like the following 'cleanup' code to your page (which closes any connection left open when the page unloads) - right in the 'using' clause:
System.Web.UI.Page page = HttpContext.Current.Handler as System.Web.UI.Page;
if (page != null) {
page.Unload += (EventHandler)delegate(object s, EventArgs e) {
try {
dbCommand.Connection.Close();
} catch (Exception) {
} finally {
result = null;
}
};
}
Also, make sure you've enabled the 'shared memory' protocoll if your SQL server and IIS are on the same machine (a real performance booster)!