Deadlock issues while converting bulk of records from DBF to CSV

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C#

ADO.NET

Hi, I am trying to convert visual box fro DBF file into CSV file using visual studio 2008 c# windows application. I am succeed in visual foxpro connection and read the file.I have used oledbdataadapter to fill dataset, I am failed here with deadlock issue because i working around 800000+ records. So i go with oledbdatareader, and read each row and wrote into the csv file. It's working fine but after writing 400000+ records am again faced deadlock issue. I need to write whole 800000+ records into a single CSV file. I have attached my code here. Please help to write 800000+ records into a single CSV .

OleDbCommand oleDbCommand = new OleDbCommand(query, oleDbConnection);
oleDbCommand.CommandTimeout = 60000;
using (OleDbDataReader oleDbDataReader = oleDbCommand.ExecuteReader())
{
    using (streamWriter1)
    {
        int fieldCount = oleDbDataReader.FieldCount;
        string columns = string.Empty;
        StringBuilder fullFile = new StringBuilder();
        for (int i = 0; i < fieldCount; i++)
        {
            columns += oleDbDataReader.GetName(i);
            if (i != fieldCount - 1)
            {
                columns += ",";
            }
        }
        fullFile.Append(columns);
        fullFile.Append("\r\n");
        streamWriter1.Write(fullFile.ToString());
        int j = 0;
        while (oleDbDataReader.Read())
        {
            j++;
            string rows = string.Empty;
            for (int i = 0; i < fieldCount; i++)
            {
                rows += oleDbDataReader.GetValue(i).ToString().Trim();
                rows += i != fieldCount - 1 ? "," : "";
            }
            fullFile = new StringBuilder();
            fullFile.Append(rows);
            fullFile.Append("\r\n");
            streamWriter1.Write(fullFile.ToString());
        }
    }
    oleDbDataReader.Close();
    oleDbCommand.Dispose();
    oleDbConnection.Close();  
}

What I have tried:

I have tried to write every 200000 records into different file. But this logic also failed with deadlock issues after 400000 record wrote.