c3p0 详细配置


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 http://www.blogjava.net/Alpha/ 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
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