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

转：http://www.wujianrong.com/archives/2007/08/c3p0.html 解决MYSQL 8小时问题

最近的一个项目在Hibernate使用C3P0的连接池，数据库为Mysql。开发测试没有问题，在运行中每个一段长的空闲时间就出现异常:

java 代码

1. org.hibernate.exception.JDBCConnectionException: could not execute query 2. at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74) 3. at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43) 4. .......

5. Caused by: com.mysql.jdbc.exceptions.MySQLNonTransientConnectionException: No

operations allowed after connection closed.Connection was implicitly closed due to underlying exception/error:

6. ** BEGIN NESTED EXCEPTION **

7. com.mysql.jdbc.CommunicationsException

8. MESSAGE: Communications link failure due to underlying exception: 9. ** BEGIN NESTED EXCEPTION ** 10. java.net.SocketException 11. MESSAGE: Broken pipe 12. STACKTRACE:

13. java.net.SocketException: Broken pipe

14. at java.net.SocketOutputStream.socketWrite0(Native Method) 15. ......

16. ** END NESTED EXCEPTION **

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。

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和C3P0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:

1. //set to 'SELECT 1'

2. validationQuery = \"SELECT 1\" 3. //set to 'true'

4. testWhileIdle = \"true\" 5. //some positive integer

6. timeBetweenEvictionRunsMillis = 3600000 7. //set to something smaller than 'wait_timeout' 8. minEvictableIdleTimeMillis = 18000000

9. //if you don't mind a hit for every getConnection(), set to \"true\" 10. testOnBorrow = \"true\"

C3P0增加以下配置信息:

1. //获取connnection时测试是否有效 2. testConnectionOnCheckin = true 3. //自动测试的table名称

4. automaticTestTable=C3P0TestTable

5. //set to something much less than wait_timeout, prevents connections from going stale

6. idleConnectionTestPeriod = 18000

7. //set to something slightly less than wait_timeout, preventing 'stale' connections from being

handed out

8. maxIdleTime = 25000

9. //if you can take the performance 'hit', set to \"true\" 10. testConnectionOnCheckout = true

更多的配置信息大家可以查看C3P0文档，Connector/J文档，以及DBCP的文档。

转: http://www.javaeye.com/article/38506

我自己的配置:

jdbc.driverClass=com.mysql.jdbc.Driver

jdbc.jdbcUrl = jdbc:mysql://localhost:3306/test jdbc.user = root jdbc.password = 12345 jdbc.miniPoolSize = 1 jdbc.maxPoolSize = 20 jdbc.initialPoolSize = 1 jdbc.maxIdleTime = 25000 jdbc.acquireIncrement = 1

jdbc.acquireRetryAttempts = 30 jdbc.acquireRetryDelay = 1000 jdbc.testConnectionOnCheckin = true jdbc.automaticTestTable = c3p0TestTable jdbc.idleConnectionTestPeriod = 18000 jdbc.checkoutTimeout=3000