谁能给段c3p0的配置文件,和java存取数据库的代码
谢谢
4条回答 默认 最新
- wanghaolovezlq 2009-09-03 21:45关注
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select id from test where id=1
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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org.hibernate.exception.JDBCConnectionException: could not execute query
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
.......
Caused by: com.mysql.jdbc.exceptions.MySQLNonTransientConnectionException: No operations allowed after connection closed.Connection was implicitly closed due to underlying exception/error:** BEGIN NESTED EXCEPTION **
com.mysql.jdbc.CommunicationsException
MESSAGE: Communications link failure due to underlying exception:** BEGIN NESTED EXCEPTION **
java.net.SocketException
MESSAGE: Broken pipeSTACKTRACE:
java.net.SocketException: Broken pipe
at java.net.SocketOutputStream.socketWrite0(Native Method)
......
** 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:
增加wait_timeout的时间。
减少Connection pools中connection的lifetime。
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:
//set to 'Select 1'
validationQuery = "Select 1"
//set to 'true'
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.iteye.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 = 1jdbc.acquireRetryAttempts = 30
jdbc.acquireRetryDelay = 1000
jdbc.testConnectionOnCheckin = true
jdbc.automaticTestTable = c3p0TestTable
jdbc.idleConnectionTestPeriod = 18000
jdbc.checkoutTimeout=3000本回答被题主选为最佳回答 , 对您是否有帮助呢?解决 无用评论 打赏 举报
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