Bug #45463 compress=true crashes in mono

Description:
The stress test in the "How to repeat" section, throws different exceptions or crashes after a few seconds when compression is enabled. It seems to be happen with Mono only. On Windows it runs fine. I will file it the Mono Bug System too.
Some different outputs follow:

########## CASE 1 ##########

Unhandled Exception: System.ArgumentException: Object must be an array of primitives.
  at System.Buffer.ByteLength (System.Array array) [0x00031] in /root/install/mono-2.4/mcs/class/corlib/System/Buffer.cs:67
  at System.Buffer.BlockCopy (System.Array src, Int32 srcOffset, System.Array dst, Int32 dstOffset, Int32 count) [0x00089] in /root/install/mono-2.4/mcs/class/corlib/System/Buffer.cs:111
  at System.IO.MemoryStream.Read (System.Byte[] buffer, Int32 offset, Int32 count) [0x00086] in /root/install/mono-2.4/mcs/class/corlib/System.IO/MemoryStream.cs:255
  at zlib.SupportClass.ReadInput (System.IO.Stream sourceStream, System.Byte[] target, Int32 start, Int32 count) [0x00000]
  at zlib.ZInputStream.read (System.Byte[] b, Int32 off, Int32 len) [0x00000]
  at MySql.Data.MySqlClient.CompressedStream.Read (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000]
  at MySql.Data.MySqlClient.CompressedStream.ReadByte () [0x00000]
  at MySql.Data.MySqlClient.MySqlStream.LoadPacket () [0x00000]
  at MySql.Data.MySqlClient.MySqlStream.ReadPacket () [0x00000]
  at MySql.Data.MySqlClient.NativeDriver.FetchDataRow (Int32 statementId, Int32 pageSize, Int32 columns) [0x00000]
  at MySql.Data.MySqlClient.MySqlDataReader.Read () [0x00000]
  at Test.MysqlStress.StressMysqlThread () [0x0009d] in MysqlStress.cs:78

########## CASE 2 ##########

Unhandled Exception: MySql.Data.MySqlClient.MySqlException: Fatal error encountered during command execution. ---> MySql.Data.MySqlClient.MySqlException: Fatal error encountered attempting to read the resultset. ---> MySql.Data.MySqlClient.MySqlException: Reading from the stream has failed. ---> zlib.ZStreamException: inflating: unknown compression method
  at zlib.ZInputStream.read (System.Byte[] b, Int32 off, Int32 len) [0x00000]
  at MySql.Data.MySqlClient.CompressedStream.Read (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000]
  at MySql.Data.MySqlClient.CompressedStream.ReadByte () [0x00000]
  at MySql.Data.MySqlClient.MySqlStream.LoadPacket () [0x00000]
  --- End of inner exception stack trace ---
  at MySql.Data.MySqlClient.MySqlStream.LoadPacket () [0x00000]
  at MySql.Data.MySqlClient.MySqlStream.ReadPacket () [0x00000]
  at MySql.Data.MySqlClient.NativeDriver.ReadResult (System.UInt64& affectedRows, System.Int64& lastInsertId) [0x00000]
  at MySql.Data.MySqlClient.MySqlDataReader.GetResultSet () [0x00000]
  at MySql.Data.MySqlClient.MySqlDataReader.NextResult () [0x00000]
  --- End of inner exception stack trace ---
  at MySql.Data.MySqlClient.MySqlDataReader.NextResult () [0x00000]
  at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader (CommandBehavior behavior) [0x00000]
  --- End of inner exception stack trace ---
  at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader (CommandBehavior behavior) [0x00000]
  at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader () [0x00000]
  at (wrapper remoting-invoke-with-check) MySql.Data.MySqlClient.MySqlCommand:ExecuteReader ()
  at MySql.Data.MySqlClient.Driver.LoadCharacterSets () [0x00000]

########## CASE 3 ##########

Unhandled Exception: MySql.Data.MySqlClient.MySqlException: Fatal error encountered during data read. ---> MySql.Data.MySqlClient.MySqlException: Reading from the stream has failed. ---> zlib.ZStreamException: inflating: unknown compression method
  at zlib.ZInputStream.read (System.Byte[] b, Int32 off, Int32 len) [0x00000]
  at MySql.Data.MySqlClient.CompressedStream.Read (System.Byte[] buffer, Int32 offset, Int32 count) [0x00000]
  at MySql.Data.MySqlClient.CompressedStream.ReadByte () [0x00000]
  at MySql.Data.MySqlClient.MySqlStream.LoadPacket () [0x00000]
  --- End of inner exception stack trace ---
  at MySql.Data.MySqlClient.MySqlStream.LoadPacket () [0x00000]
  at MySql.Data.MySqlClient.MySqlStream.ReadPacket () [0x00000]
  at MySql.Data.MySqlClient.NativeDriver.FetchDataRow (Int32 statementId, Int32 pageSize, Int32 columns) [0x00000]
  at MySql.Data.MySqlClient.MySqlDataReader.Read () [0x00000]
  --- End of inner exception stack trace ---
  at MySql.Data.MySqlClient.MySqlDataReader.Read () [0x00000]
  at Test.MysqlStress.StressMysqlThread () [0x0009d] in MysqlStress.cs:78

How to repeat:
namespace Test {
	
	using System;
	using System.Collections.Generic;
	using System.Data.Common;
	using System.Text;
	using System.Threading;
	using MySql.Data.MySqlClient;
	
	class MysqlStress {

		static string connectionString =
			"Host=192.168.0.204;Uid=root;Pwd=secret;Database=test;" +
			"Charset=utf8;Compress=true;Convert Zero Datetime=true"
		;
		static int maxRows = 100;

		public static void Main( string[] args ) {
			StressMysql();
		}
		
		public static void StressMysql() {
			MySqlConnection con = new MySqlConnection( connectionString );
			con.Open();
			MySqlCommand cmd = new MySqlCommand();
			cmd.Connection = con;
			cmd.CommandText = "DROP TABLE IF EXISTS t1";
			cmd.ExecuteNonQuery();
			cmd.CommandText =
				@"CREATE TABLE t1 (
					id INT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
					ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
					dt DATETIME,
					ch VARCHAR(255) CHARACTER SET utf8,
					bn VARBINARY(255),
					tx TEXT CHARACTER SET utf8
				)"
			;
			cmd.ExecuteNonQuery();
			cmd.CommandText = "INSERT INTO t1 (dt,ch,bn,tx) VALUES(?dt,?ch,?bn,?tx)";
			cmd.Parameters.Clear();
			cmd.Parameters.Add( "?dt", MySqlDbType.DateTime );
			cmd.Parameters.Add( "?ch", MySqlDbType.VarChar );
			cmd.Parameters.Add( "?bn", MySqlDbType.VarBinary );
			cmd.Parameters.Add( "?tx", MySqlDbType.Text );
			cmd.Prepare();
			for( int i = 1; i <= maxRows; i++ ) {
				cmd.Parameters[0].Value = DateTime.Now;
				cmd.Parameters[1].Value = i.ToString() + new String( 'X', 200 );
				cmd.Parameters[2].Value = Encoding.ASCII.GetBytes( i.ToString() + new String( 'X', 200 ) );
				cmd.Parameters[3].Value = new String( 'X', 16384 );
				cmd.ExecuteNonQuery();
				Console.WriteLine( "insert row {0}", i );
			}
			List<Thread> threads = new List<Thread>();
			for( int i = 1; i <= 10; i++ ) {
				Thread thread = new Thread(
					new ThreadStart( StressMysqlThread ) );
				thread.Start();
				threads.Add( thread );
			}
			while( true ) {
				Thread.Sleep( 1000 );
			}
		}

		public static void StressMysqlThread() {
			MySqlConnection con = new MySqlConnection( connectionString );
			con.Open();
			while( true ) {
				MySqlCommand cmd = new MySqlCommand();
				Random rand = new Random();
				cmd.Connection = con;
				cmd.CommandText = "SELECT * FROM t1 WHERE id > " + rand.Next( maxRows - 1 );
				Console.WriteLine( cmd.CommandText );
				DbDataReader res = cmd.ExecuteReader();
				Dictionary<string, object> row = new Dictionary<string,object>();
				while( res.Read() ) {
					row.Clear();
					for( int i = 0; i < res.FieldCount; i++ )
						row[res.GetName( i )] = res[i];
				}
				res.Close();
				Thread.Sleep( rand.Next( 1000 ) );
			}
		}
	}
}

Hi Christian and thanks for your report.

Actually, cases 2 and 3 seem identical and related to:
Version 5.0.1 (Beta)

  ----------cut-----------
  Other changes
  -------------
  Replaced use of .NET 2.0 compression code with open source zlib library
  Fixed compression

Do you have open source zlib library?

Case 1 seems to be related to Bug#28204 but that should be fixed already. Can you confirm your problems on some other box, especially if it doesn't exhibit problems 2 and 3?

Hi,

since it happens in all versions 5.0, 5.1, 5.2, 6.0 of the net-connector but only with mono (tested 2.4 and svn snapshot) and your driver is 100% managed (right?), it could be propably a mono runtime problem. Case 4 was a crash of mono, but it was to big to send it with the report. I will try to attach it. It's also not clear which exception raise. It looks like a C buffer overrun with undefined result.

Christian

MysqlStress.out

Attachment: MysqlStress.out (text/plain), 24.42 KiB.

I have open source zlib library. What should i do with it?

Tests on Ubuntu 9 32-bit with build in mono 2.0.1 show the same results.

Christian.

Google search reveals many many troubles with mono/ZLib combination. Have you checked with mono-project to see if this is actually their problem?

verified but not sure yet if this is truly a bug in c/net

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/76506

fixed in 5.2.7 and 6.0.5+

We believe this is a bug in Mono.  We had to not use WeakReferences in our Compressed stream class to avoid this crash.

An entry was added to both the 5.2.7 and the 6.0.5 changelogs:

A Connector/NET test program that connected to MySQL Server using the connection string option compress=true crashed, but only when running on Mono. The program worked as expected when running on Microsoft Windows.

This was due to a bug in Mono. Connector/NET was modified to avoid using WeakReferences in the Compressed stream class, which was causing the crash.

Thank you very much. Hopefully it will help somebody else too.
Light and love to everybody :)