MYSQL connector 的 NullReferenceException bug

mysql connector 連線報錯，  客戶端在 MySqlClient.MySqlDataReader.NextResult() 處報錯 ,IIS 程式池 crash 後 db 端提示 Got an error reading communication packets 。

異常時堆疊呼叫資訊：

ServerConnectionInfo.Finallize()

=>ServerConnectionInfo.Dispose()

=>MySqlConnection.Dispose()

=>MySqlConnection.Close()

=>MySqlDataReader.Close()

=》MySqlDataReader.NextResult()

     從堆疊呼叫資訊來看，是從程式中發起了Dispose()，後再呼叫了MySqlConnection.Dispose()進行關閉。         在這裡MySqlConnection.Close()又呼叫MySqlDataReader.Close()=》MySqlDataReader.NextResult()，從應用程式碼瞭解到MySqlConnection.Close()一般應為正常關閉的最後一步，而MySqlDataReader.Close()應在MySqlConnection.Close()之厚，這看起來是個非正常行為。

    

     報錯資訊與connector 的 Bug#91106 NullReferenceException in Finalize crashes applications及Bug#90845 

NullReferenceException on connection close比較匹配，易工已透過修改connetor原始碼進行測試。

Bug#90845：

Description:

A NullReferenceException is thrown on MySqlConnection Dispose

The NullReference came from the setter of the property Reader.

In the getter the driver has a null check but in the setter it is treated as a NotNull value

Bug#91106

Suggested fix:

       The MySqlDataReader that is used underneath by the command and dataadapter should have been disposed of when the commmand and dataadapter were disposed. I think that is probably a bug.

       If it wasn't disposed of correctly then, the finalize method should not assume the driver and driver.stream are not null. or you can catch these exceptions in dispose and not crash the program.