nutz连接mysql异常处理：MySQLNonTransientConnectionException: No operations allowed after connection closed

异常信息（部分）：

2014-11-26 12:01:47,815 [http-6888-6] WARN  com.mchange.v2.c3p0.impl.NewPooledConnection - [c3p0] A PooledConnection that has already signalled a Connection error is still in use!

2014-11-26 12:01:47,829 [http-6888-6] WARN  com.mchange.v2.c3p0.impl.NewPooledConnection - [c3p0] Another error has occurred [ com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed. ] which will not be reported to listeners!
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
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:408)
at com.mysql.jdbc.Util.getInstance(Util.java:383)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1023)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:997)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:983)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:928)
at com.mysql.jdbc.ConnectionImpl.throwConnectionClosedException(ConnectionImpl.java:1323)
at com.mysql.jdbc.ConnectionImpl.checkClosed(ConnectionImpl.java:1315)
at com.mysql.jdbc.ConnectionImpl.rollback(ConnectionImpl.java:5057)

at com.mchange.v2.c3p0.impl.NewProxyConnection.rollback(NewProxyConnection.java:855)

原因分析

查看了Mysql的文档，以及Connector/J的文档以及在线说明发现，出现这种异常的原因是：

　　Mysql服务器默认的“wait_timeout”是8小时，也就是说一个connection空闲超过8个小时，Mysql将自动断开该connection。这就是问题的所在，在C3P0 pools中的connections如果空闲超过8小时，Mysql将其断开，而C3P0并不知道该connection已经失效，如果这时有Client请求connection，C3P0将该失效的Connection提供给Client，将会造成上面的异常。

nutz配置解决方案：

myapp.properties信息

db-driver=com.mysql.jdbc.Driver
db-url=jdbc:mysql://localhost:3306/mydb?useUnicode=true&characterEncoding=UTF-8
db-username=mytest
db-password=123456

core.js信息

var ioc = {

config : {
type : "org.nutz.ioc.impl.PropertiesProxy",
fields : {
paths : ["/conf/myapp.properties"]
}
},

dataSource : {
type :"com.mchange.v2.c3p0.ComboPooledDataSource",
events : {
depose :"close"
},
fields : {
driverClass : {java :"$config.get('db-driver')"},
jdbcUrl             : {java :"$config.get('db-url')"},
user        : {java :"$config.get('db-username')"},
password        : {java :"$config.get('db-password')"},
minPoolSize     : 5,
initialPoolSize : 10,
maxPoolSize     : 100,
testConnectionOnCheckin : true,
automaticTestTable : "C3P0TestTable",      －－    这些是针对MySQLNonTransientConnectionException新加的属性
idleConnectionTestPeriod : 18000,
maxIdleTime : 300,
maxStatements : 0,          －－防止c3p0 APPARENT DEADLOCK的问题
numHelperThreads : 5    －－防止c3p0 APPARENT DEADLOCK的问题
}
},
// Dao
dao : {
type :'com.test.my.TestDao',
args : [ {refer :"dataSource"}]
}
};

com.test.my.TestDao 类，该类直接继承了NutDao ，如果非必要，那么type里面可以直接写NutDao 。

public class TestDao extends NutDao {


public TestDao () {
super();
// TODO Auto-generated constructor stub
}


public TestDao (DataSource dataSource, SqlManager sqlManager) {
super(dataSource, sqlManager);
// TODO Auto-generated constructor stub
}


public TestDao (DataSource dataSource) {
super(dataSource);
// TODO Auto-generated constructor stub
}

//下面是一些自己的方法
}

解决方案

解决的方法有3种：

1. 增加 wait_timeout 的时间。
2. 减少 Connection pools 中 connection 的 lifetime。
3. 测试 Connection pools 中 connection 的有效性。

当然最好的办法是同时综合使用上述3种方法，下面就 DBCP、C3P0 和 simple jdbc dataSource 分别做一说明，假设 wait_timeout 为默认的8小时

DBCP 增加以下配置信息:

validationQuery = "select 1"

testWhileIdle = "true"

//some positive integer
timeBetweenEvictionRunsMillis = 3600000

//set to something smaller than 'wait_timeout'
minEvictableIdleTimeMillis = 18000000

//if you don't mind a hit for every getConnection(), set to "true"
testOnBorrow = "true"

C3P0 增加以下配置信息:

//获取connnection时测试是否有效
testConnectionOnCheckin = true

//自动测试的table名称
automaticTestTable=C3P0TestTable

//set to something much less than wait_timeout, prevents connections from going stale
idleConnectionTestPeriod = 18000

//set to something slightly less than wait_timeout, preventing 'stale' connections from being handed out
maxIdleTime = 25000

//if you can take the performance 'hit', set to "true"
testConnectionOnCheckout = true

simple jdbc dataSource 增加以下配置信息:

Pool.PingQuery = select 1

Pool.PingEnabled = true

Pool.PingConnectionsOlderThan = 0

//对于空闲的连接一个小时检查一次
Pool.PingConnectionsNotUsedFor = 3600000

其他方案（不推荐）

　　对于 MySQL5 之前的版本，如 Mysql4.x，只需要修改连接池配置中的 URL，添加一个参数：autoReconnect=true(如jdbc:mysql://hostaddress:3306/schemaname?autoReconnect=true)，如果是 MySQL5 及以后的版本，则需要修改 my.cnf(或者my.ini) 文件，在 [mysqld] 后面添加上：

wait_timeout = n
interactive-timeout = n

其中 n 为服务器关闭交互式连接前等待活动的秒数。可是就部署而言每次修改 my.ini 比较麻烦，而且 n 等于多少才是合适的值呢？ 所以并不推荐这个解决办法。)

c3p0详细配置

官方文档 :  http://www.mchange.com/projects/c3p0/index.html

3


30


1000


false


Test


false


100





null


false


60


3


60


15


100





3


root


password





select id from test where id=1


300


false


true


root


false

con_test
30000
30
10
30
25
10
0




200

300

参考：

http://www.blogjava.net/Alpha/archive/2009/03/29/262789.html

http://blog.csdn.net/bedweather/article/details/6743951

http://www.cnblogs.com/hemingwang0902/archive/2012/03/15/2397620.html
http://blog.sina.com.cn/s/blog_53b58e7c010197bj.html