MySQL Connector .NET 1.0.6 and "Connection unexpectedly terminated" exception

[Sven Jacobs]

Dear newsgroup,

I'm having a critical problem with the MySQL Connector .NET 1.0.6. I'm
developing a .NET (Version 1.1 SP1) application on a Windows 2000
Professional machine with MySQL Server 4.1.14.

A huge SQL query does run for about 40 minutes but then aborts with the
exception "Connection unexpectedly terminated". If I comment out some time
and memory consuming calculations the query does run a bit further but then
also terminates. It seems like there is a relation between the memory used
by my application (which constantly grows while it's running) and this
problem. I am using a MySqlReader to fetch the results row by row. I found
out that if I am using a "classical" MySqlQuery, apply a LIMIT on the SQL
and call it several times (with different LIMITs of course), the problem
does not occur BUT this is certainly not as high-performance as using a
MySqlReader.

The bug is registered in the MySQL bug tracking system
([url]http://bugs.mysql.com/bug.php?id=6688[/url]) since 17th November of last year
(!) and there has been no fix.

I also tried MySQL Server 4.1.15 and 5.0.15 -> same problem.

I wonder if anyone came across this problem and found a resolution?

--
Sincerely
Sven Jacobs

[Sven Jacobs]

> I'm having a critical problem with the MySQL Connector .NET 1.0.6. I'm

> developing a .NET (Version 1.1 SP1) application on a Windows 2000
> Professional machine with MySQL Server 4.1.14.
>
> [...]

I think I found the cause and solution to this problem! I was able to
reproduce this bug with the following small piece of C# code:

try
{
// Edit connection settings here!
MySqlConnection conn = new MySqlConnection( "server=localhost;user
id=xxx;password=yyy;database=zzz;port=3306" );
conn.Open();

// Do a SELECT on a table with many rows here!
MySqlCommand cmd = new MySqlCommand( "SELECT * FROM xyz LIMIT 1000", conn
);
MySqlDataReader reader = cmd.ExecuteReader();

while ( reader.Read() )
{
// Let's sleep for a moment. Important for reproducing the bug!
Thread.Sleep( 2400 );
}

MessageBox.Show( this, "Done" );
}
catch( Exception ex )
{
MessageBox.Show( this, ex.Message, "Exception!", MessageBoxButtons.OK,
MessageBoxIcon.Error );
}

Since the bug seems to be strongly connected to some timeout, I've tried to
manipulate several server variables which are related to timeout settings.
I found out that if the value of the variable net_write_timeout is
increased to 3600 (previously 60) the error does not occur!

For further details please see bug report at
[url]http://bugs.mysql.com/bug.php?id=6688[/url]

--
Sincerely
Sven Jacobs