On what objects we should use dispose method ? C# 4.0

Question

Ok here i am going to list objects of my software. Currently memory usage is increasing by the time passes, though it should not increase because i am not keeping any resources. Using only database.

c# 4.0 , visual studio 2010

Lets start with objects. On these objects should i ever call dispose or use "using"

string variable;
int variable;
dataset variable;
HtmlDocument variable;
List<string> variable;
HtmlNode variable;
Uri variable;
DateTime variable;
HtmlWeb variable;
Regex variable;
MatchCollection variable;
bool variable;

piece of code (anything required after File.WriteAllText ? method)

                File.WriteAllText("hatalar/" + UtcTimeNow.Ticks.ToString() + GenerateRandomValue.GenerateRandomValueDefault(10000000) + ".txt", srCrawledUrl + " unknown error page id " + srPageId);

piece of code

                if (irFinishedLast > -1)
            {
                var newTask = Task.Factory.StartNew(() =>
                {
                    fcStartSubPageCrawl(srMainSiteURL, srMainSiteId, irWhichMainTask);
                });
                lock (lockerMainSitesArray)
                {
                    if (MainSitesTaskList[irWhichMainTask, irFinishedLast] != null)
                        MainSitesTaskList[irWhichMainTask, irFinishedLast].Dispose();
                    MainSitesTaskList[irWhichMainTask, irFinishedLast] = newTask;
                }
            }

Alright now classes and functions. Public static function which is being called by many threads at the same time. It is inside public static class.

public static string srInserIntoPagesCommand = "insert into myTable (PageUrl,MainSiteId,CrawlDateInt,CrawlDateChar,CrawlDepth,ExtractedPageId,CrawlStatus) values " +
            "(@PageUrl,@MainSiteId,@CrawlDateInt,@CrawlDateChar,@CrawlDepth,@ExtractedPageId,@CrawlStatus)";

        public static bool InsertIntoPages(string PageUrl, string MainSiteId, string CrawlDateInt, string CrawlDateChar, string CrawlDepth, string ExtractedPageId, string CrawlStatus)
        {
            string srPageUrl = PageUrl;
            string srMainSiteId = MainSiteId;
            string srCrawlDateInt = CrawlDateInt;
            string srCrawlDateChar = CrawlDateChar;
            string srCrawlDepth = CrawlDepth;
            string srExtractedPageId = ExtractedPageId;
            string srCrawlStatus = CrawlStatus;

            if (srCrawlDateInt.Length < 1)
                srCrawlDateInt = "0";
            if (srCrawlDateChar.Length < 1)
                srCrawlDateChar = "null";
            if (srCrawlStatus.Length < 1)
                srCrawlStatus = "0";

            using (SqlConnection connection = new SqlConnection(DbConnection.srConnectionString))
            {
                using (SqlCommand cmd = new SqlCommand(srInserIntoPagesCommand, connection))
                {
                    cmd.CommandType = CommandType.Text;
                    cmd.Parameters.AddWithValue("@PageUrl", srPageUrl);
                    cmd.Parameters.AddWithValue("@MainSiteId", srMainSiteId);
                    cmd.Parameters.AddWithValue("@CrawlDateInt", srCrawlDateInt);
                    cmd.Parameters.AddWithValue("@CrawlDateChar", srCrawlDateChar);
                    cmd.Parameters.AddWithValue("@CrawlDepth", srCrawlDepth);
                    cmd.Parameters.AddWithValue("@ExtractedPageId", srExtractedPageId);
                    cmd.Parameters.AddWithValue("@CrawlStatus", srCrawlStatus);
                    try
                    {
                        connection.Open();
                        cmd.ExecuteNonQuery();
                    }
                    catch (Exception E)
                    {
                        DateTime UtcTimeNow = DateTime.UtcNow;
                        File.WriteAllText("pageshatalar/" + UtcTimeNow.Ticks.ToString() + GenerateRandomValue.GenerateRandomValueDefault(1000000) + ".txt", "InsertIntoPages \r\n\r\n" + E.Message.ToString() + "\r\n\r\n" + srPageUrl);
                        return false;
                    }
                }
                connection.Close();
            }
            return true;
        }

public static database connection for select queries mostly inside public static class

public static string srConnectionString = "server=localhost;database=mydb;uid=sa;pwd=mypw; Max Pool Size=20000; Pooling=True;";

public static DataSet db_Select_Query(string strQuery)
{
    DataSet dSet = new DataSet();
    try
    {
        using (SqlConnection connection = new SqlConnection(srConnectionString))
        {
            connection.Open();
            using (SqlDataAdapter DA = new SqlDataAdapter(strQuery, connection))
            {
                DA.Fill(dSet);
            }
            connection.Close();
        }
        return dSet;
    }
    catch
    {
        DateTime UtcTimeNow = DateTime.UtcNow;
        File.WriteAllText("sqlhatalar/" + UtcTimeNow.Ticks.ToString() + GenerateRandomValue.GenerateRandomValueDefault(1000000) + ".txt", strQuery);
        return null;
    }
}

Answer 1

If for some bizarre reason you don't know at run-time if an object has dispose implemented, you can use this dispose-safe function:

/// ---- IsDisposable --------------------------------
///
/// <summary>
/// returns true if an object is disposable, false if not
/// you can optionally dispose of it immediately
/// </summary>

public static Boolean IsDisposable(Object Item, Boolean DeleteIfDisposable)
{
    if (Item is IDisposable)
    {
        if (DeleteIfDisposable)
        {
            IDisposable DisposableItem;
            DisposableItem = (IDisposable)Item;
            DisposableItem.Dispose();
        }
        return true;
    }
    else
        return false;
}