Re: Connector/J "Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost."

[Gang Lau]

I saw the same error after I changed connectorJ 3.1.10 to 5.1.5 last night.Before it is ok.

MySQL DB and J2SE program are in the same machine, using 127.0.0.1 to connect.Using hibernate 3.0 and our own very simple connection pool implementation.

java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Client VM (build 1.6.0_03-b05, mixed mode, sharing)

GNU/Linux Version: CentOS release 4.6 (Final)
[root@kk2 ~]# uname -a
Linux kk2 2.6.9-67.0.4.ELsmp #1 SMP Sun Feb 3 07:08:57 EST 2008 i686 i686 i38 6 GNU/Linux

MySQL Version:
mysql> status
--------------
mysql Ver 14.7 Distrib 4.1.20, for redhat-linux-gnu (i686) using readline 4.3

Connection id: 212
Current database:
Current user: root@localhost
SSL: Not in use
Current pager: stdout
Using outfile: ''
Using delimiter: ;
Server version: 4.1.20
Protocol version: 10
Connection: Localhost via UNIX socket
Server characterset: latin1
Db characterset: latin1
Client characterset: latin1
Conn. characterset: latin1
UNIX socket: /var/lib/mysql/mysql.sock
Uptime: 2 hours 55 min 55 sec

Threads: 16 Questions: 1719338 Slow queries: 1 Opens: 47 Flush tables: 1 Open tables: 41 Queries per second avg: 162.893
--------------

2008-02-12 11:27:40,830 [THREAD_POOL_THREAD_28] ERROR org.hibernate.transaction.JDBCTransaction - JDBC begin failed
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 0 ms ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2873)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2763)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3299)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1837)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1961)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2537)
at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:4836)
at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:53)
at org.hibernate.transaction.JDBCTransactionFactory.beginTransaction(JDBCTransactionFactory.java:24)
at org.hibernate.jdbc.JDBCContext.beginTransaction(JDBCContext.java:271)
at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1079)
at cc.media.gs.dao.SwitchDAOImpl.getSwitch(SwitchDAOImpl.java:94)
at cc.media.gs.dao.SwitchProxy.getSwitch(SwitchProxy.java:54)
at cc.media.gs.dae.RequestHandler.run(RequestHandler.java:54)
at util.ThreadPool$Pooled_thread.run(ThreadPool.java:76)
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2332)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2774)
... 14 more