Sql Compact randomly produces AccessViolationException

Question

I am running Sql Server Compact Edition 3.5.1.0 SP1 in a multi-thread application. The application randomly runs insert queries in transactions. With short transactions, it works fine. But when the transactions get longer and delay between executions get shorter or when I run the application in debug mode, SqlCE begins to throw the following exception randomly:

AccessViolationException Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

at System.Data.SqlServerCe.SqlCeCommand.CompileQueryPlan() at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommand(CommandBehavior behavior, String method, ResultSetOptions options) at System.Data.SqlServerCe.SqlCeCommand.ExecuteNonQuery() at SqlCompactTest.TransactedCommandGroupExecutionTest.Test() in D:\Projects\PlayGround\SqlCompactTest\SqlCompactTest\TransactedCommandGroupExecutionTest.cs:line 53 at SqlCompactTest.ExecutionTest.RunTest() in D:\Projects\PlayGround\SqlCompactTest\SqlCompactTest\ExecutionTest.cs:line 60 at SqlCompactTest.ExecutionTest.TimerElapsed(Object sender, ElapsedEventArgs e) in D:\Projects\PlayGround\SqlCompactTest\SqlCompactTest\ExecutionTest.cs:line 68 at System.Timers.Timer.MyTimerCallback(Object state)

The code I am running is:

IDbConnection connection = m_connectionProvider.GetConnection(); // Just returns new connection

connection.Open();
IDbTransaction transaction = connection.BeginTransaction();

foreach (IDbCommand command in m_commands)
{
    command.Connection = connection;
    command.ExecuteNonQuery(); // This line throws exception
    Thread.Sleep((int)m_delayBetweenExecutions);
}

transaction.Commit();
connection.Close();

This code is running simultaneously in two threads. Connection string is:

"Data Source=testDB.sdf;Encrypt Database=True;Password=test;File Mode=Read Write;Persist Security Info=False;Max Database Size=1024"

I found absurd solutions on Internet like reverting back to Framework 1.1, changing the order of method arguments, enabling/disabling optimizations etc. but none of them worked for me. I also iterated through possible solutions on microsoft sites but I could not find a solution that works for me. My database file version is 3.5.0.0.

How can I solve this?

Answer 1

Just because you set a connection to command.Connection does not mean it is set.

command.Connection = connection;
command.Connection.GetHashCode() == connection.GetHashCode(); // may return false.

This is the cause of the problem. Can be corrected by using connection.CreateCommand();