Devart Forums

Hello,

I'm working on a batch read-only multi-threaded application using massively SQLiteDataReader. This application is working fine and very fast using System.Data.SQLite with basic connect String like "Data Source=..." and no optionnal settings. When changing drivers to last version of "dotConnect for Sqlite", keeping exactly the same code, and using 1 thread, the application is running as fine as it was running with System.Data.SQLite drivers.
Problems occurs when using more than 1 thread with dotConnect drivers while it's working fine with many thread and System.Data.SQLite drivers.

The error was still the same and appears randomly :

System.AccessViolationException was unhandled
Message=Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
Source=Devart.Data.SQLite
StackTrace:
at Devart.Data.SQLite.bc.sqlite3_column_type(IntPtr A_0, Int32 A_1)
at Devart.Data.SQLite.a3.a(bs A_0, Int32 A_1, SQLiteType& A_2)
at Devart.Data.SQLite.SQLiteDataReader.c(Int32 A_0)
at Devart.Data.SQLite.SQLiteDataReader.GetSQLiteType(Int32 i)
at Devart.Data.SQLite.SQLiteDataReader.GetValue(Int32 i)
at Devart.Common.DbDataReaderBase.get_Item(String name)
...

Any help about this is welcome.

Thx in advance

i've resolve my problem but it's a bit strange ...

explanation : most of my C# code querying SQLite was like this :

SQLiteCommand command = new SQLiteCommand(...);
command.CommandText = "SELECT * ...";
SQLiteDataReader reader = command.ExecuteReader(CommandBehavior.CloseConnection);
while (reader.Read())
{
...
}


and changing it the next syntax resolve my problem :

SQLiteCommand command = new SQLiteCommand(...);
command.CommandText = "SELECT * ...";
SQLiteDataReader reader = command.ExecuteReader();
while (reader.Read())
{
...
}
reader.Close();

Can someone help me to understand why it was a problem to use the CommandBehavior.CloseConnection ?

Thx

You have to explicitly call the SQLiteDataReader.Close() method when you are finished using the SQLiteDataReader to use the associated SQLiteConnection for any other purpose (MSDN).

lpg2000 wrote:Can someone help me to understand why it was a problem to use the CommandBehavior.CloseConnection ?

Please refer to http://msdn.microsoft.com/en-us/library ... avior.aspx:
"CommandBehavior.CloseConnection - When the command is executed, the associated Connection object is closed when the associated DataReader object is closed." But you do not call reader.Close() in the first case.