Description:
A couple of times every month we get the same exception (43 exceptions for 2 years to be exact):
-----------------------------------------------------
Exception type: MySql.Data.MySqlClient.MySqlException
Exception message: Unable to connect to any of the specified MySQL hosts.
Additional/private data:
Server Error Code: 1042
Stack trace:
at MySql.Data.MySqlClient.NativeDriver.Open() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\NativeDriver.cs:line 203
at MySql.Data.MySqlClient.Driver.Open() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\Driver.cs:line 211
at MySql.Data.MySqlClient.Driver.Create(MySqlConnectionStringBuilder settings) in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\Driver.cs:line 199
at MySql.Data.MySqlClient.MySqlPool.CreateNewPooledConnection() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\MySqlPool.cs:line 172
at MySql.Data.MySqlClient.MySqlPool.GetPooledConnection() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\MySqlPool.cs:line 155
at MySql.Data.MySqlClient.MySqlPool.TryToGetDriver() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\MySqlPool.cs:line 244
at MySql.Data.MySqlClient.MySqlPool.GetConnection() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\MySqlPool.cs:line 257
at MySql.Data.MySqlClient.MySqlConnection.Open() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\Connection.cs:line 499
at RA.Common.DAL.DbManager.InitConnection() in C:\VCProjects\Alex\RA\RA.Common\DAL\DbManager.cs:line 52
at RA.Common.DAL.DbManager..ctor(Boolean createSeparateConnectionEvenIfUnderLocalTransaction) in C:\VCProjects\Alex\RA\RA.Common\DAL\DbManager.cs:line 90
at RA.Common.DAL.DbManager..ctor() in C:\VCProjects\Alex\RA\RA.Common\DAL\DbManager.cs:line 81
at RA.Common.DAL.ServerAccessor.GetServerCurrentDateTime() in C:\VCProjects\Alex\RA\RA.Common\DAL\ServerAccessor.cs:line 13
at RA.ClientForms.MainForm.CheckTimeDifferenceWithServer(Object sender, EventArgs e) in C:\VCProjects\Alex\RA\RA\ClientForms\MainForm.cs:line 527
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
Inner exception:
Exception type: System.Net.Sockets.SocketException
Message: A socket operation was attempted to an unreachable host 192.168.1.141:3306
Stack trace:
at System.Net.Sockets.Socket.EndConnect(IAsyncResult asyncResult)
at MySql.Data.Common.StreamCreator.CreateSocketStream(IPAddress ip, Boolean unix)
at MySql.Data.Common.StreamCreator.GetStreamFromHost(String pipeName, String hostName, UInt32 timeout)
at MySql.Data.Common.StreamCreator.GetStream(UInt32 timeout)
at MySql.Data.MySqlClient.NativeDriver.Open()
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As I said, the exception is always the same, occurs only in 1 place (in the function that is called every 10 minutes by timer). There is no other occurrences of such an exception in another places of our 100KLOC application. Everything is working fine, but, as I said, ~2 times a month we get this exception.
Our details:
------------
Current MySql Server version: 5.1.58 (but the problem also occurred with older versions)
Current MySql Connector/Net version: 6.5.4 (but the problem also occurred with older versions)
Number of concurrent users: 5-7 (clients and mysql server are in local network)
The exception occurs on different machines: YES
Connection string: "server={0};database={1};User Id={2};password={3};Character Set=utf8"
The function that is called every 10 minutes by timer:
------------------------------------------------------
public static DateTime GetServerCurrentDateTime()
{
using (var db = new DbManager())
{
return Convert.ToDateTime(db.ExecuteScalar("SELECT NOW()"));
} // connection is disposed and returned to a connection pool
}
DbManager is just a wrapper around MySqlConnection, it just creates and opens a connection like this:
_conn = _dataProvider.CreateConnectionObject();
_conn.ConnectionString = _connectionString;
_conn.Open();
Our considerations:
-------------------
I believe it's somehow related to using a timer, or to a repetitive call. Maybe it's somehow related to connection pool.
Also, here is a thread where similar/same problem is discussed:
http://forums.mysql.com/read.php?38,13350,13350#msg-13350
and some people also noted that the exception occurs in the function that is called by a timer.
How to repeat:
---
Description: A couple of times every month we get the same exception (43 exceptions for 2 years to be exact): ----------------------------------------------------- Exception type: MySql.Data.MySqlClient.MySqlException Exception message: Unable to connect to any of the specified MySQL hosts. Additional/private data: Server Error Code: 1042 Stack trace: at MySql.Data.MySqlClient.NativeDriver.Open() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\NativeDriver.cs:line 203 at MySql.Data.MySqlClient.Driver.Open() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\Driver.cs:line 211 at MySql.Data.MySqlClient.Driver.Create(MySqlConnectionStringBuilder settings) in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\Driver.cs:line 199 at MySql.Data.MySqlClient.MySqlPool.CreateNewPooledConnection() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\MySqlPool.cs:line 172 at MySql.Data.MySqlClient.MySqlPool.GetPooledConnection() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\MySqlPool.cs:line 155 at MySql.Data.MySqlClient.MySqlPool.TryToGetDriver() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\MySqlPool.cs:line 244 at MySql.Data.MySqlClient.MySqlPool.GetConnection() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\MySqlPool.cs:line 257 at MySql.Data.MySqlClient.MySqlConnection.Open() in C:\VCProjects\MySQL Connector .NET\Source\MySql.Data\Connection.cs:line 499 at RA.Common.DAL.DbManager.InitConnection() in C:\VCProjects\Alex\RA\RA.Common\DAL\DbManager.cs:line 52 at RA.Common.DAL.DbManager..ctor(Boolean createSeparateConnectionEvenIfUnderLocalTransaction) in C:\VCProjects\Alex\RA\RA.Common\DAL\DbManager.cs:line 90 at RA.Common.DAL.DbManager..ctor() in C:\VCProjects\Alex\RA\RA.Common\DAL\DbManager.cs:line 81 at RA.Common.DAL.ServerAccessor.GetServerCurrentDateTime() in C:\VCProjects\Alex\RA\RA.Common\DAL\ServerAccessor.cs:line 13 at RA.ClientForms.MainForm.CheckTimeDifferenceWithServer(Object sender, EventArgs e) in C:\VCProjects\Alex\RA\RA\ClientForms\MainForm.cs:line 527 at System.Windows.Forms.Timer.OnTick(EventArgs e) at System.Windows.Forms.Timer.TimerNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) Inner exception: Exception type: System.Net.Sockets.SocketException Message: A socket operation was attempted to an unreachable host 192.168.1.141:3306 Stack trace: at System.Net.Sockets.Socket.EndConnect(IAsyncResult asyncResult) at MySql.Data.Common.StreamCreator.CreateSocketStream(IPAddress ip, Boolean unix) at MySql.Data.Common.StreamCreator.GetStreamFromHost(String pipeName, String hostName, UInt32 timeout) at MySql.Data.Common.StreamCreator.GetStream(UInt32 timeout) at MySql.Data.MySqlClient.NativeDriver.Open() ----------------------------------------------------- As I said, the exception is always the same, occurs only in 1 place (in the function that is called every 10 minutes by timer). There is no other occurrences of such an exception in another places of our 100KLOC application. Everything is working fine, but, as I said, ~2 times a month we get this exception. Our details: ------------ Current MySql Server version: 5.1.58 (but the problem also occurred with older versions) Current MySql Connector/Net version: 6.5.4 (but the problem also occurred with older versions) Number of concurrent users: 5-7 (clients and mysql server are in local network) The exception occurs on different machines: YES Connection string: "server={0};database={1};User Id={2};password={3};Character Set=utf8" The function that is called every 10 minutes by timer: ------------------------------------------------------ public static DateTime GetServerCurrentDateTime() { using (var db = new DbManager()) { return Convert.ToDateTime(db.ExecuteScalar("SELECT NOW()")); } // connection is disposed and returned to a connection pool } DbManager is just a wrapper around MySqlConnection, it just creates and opens a connection like this: _conn = _dataProvider.CreateConnectionObject(); _conn.ConnectionString = _connectionString; _conn.Open(); Our considerations: ------------------- I believe it's somehow related to using a timer, or to a repetitive call. Maybe it's somehow related to connection pool. Also, here is a thread where similar/same problem is discussed: http://forums.mysql.com/read.php?38,13350,13350#msg-13350 and some people also noted that the exception occurs in the function that is called by a timer. How to repeat: ---