Tomcat 数据库连接池 与 mysql wait_timeout 问题

[wy13tx]

用户从连接池中取出连接后，使用完立刻关闭，然后时间超过 mysql 中的 wait_timeout 值。再从连接池中取出一个连接，使用时报错如下！！！！！ 如果不修改 wait_timeout 的值，还有什么办法？？？？？

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 15 ms ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
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:2985)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2871)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3414)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2536)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2465)
at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1383)
at org.apache.tomcat.dbcp.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:208)
at org.apache.tomcat.dbcp.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:208)
at useConn.UserConn.test(UserConn.java:127)
at useConn.UserConn.printUser(UserConn.java:63)
at org.apache.jsp.connTest_jsp._jspService(connTest_jsp.java:80)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.net.SocketException: Software caused connection abort: recv failed
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(Unknown Source)
at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:113)
at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:160)
at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:188)
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2428)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2882)
... 33 more

[iihero]

#最大等待时间:当没有可用连接时,连接池等待连接被归还的最大时间(以毫秒计数),超过时间则抛出异常,如果设置为-1表示无限等待 默认值:无限 maxWait=28000 ######################## #SQL查询,用来验证从连接池取出的连接,在将连接返回给调用者之前.如果指定,则查询必须是一个SQL SELECT并且必须返回至少一行记录 validationQuery=select 1 #指明是否在从池中取出连接前进行检验,如果检验失败,则从池中去除连接并尝试取出另一个. #注意: 设置为true后如果要生效,validationQuery参数必须设置为非空字符串 默认值:true testOnBorrow # 指明是否在归还到池中前进行检验 #注意: 设置为true后如果要生效,validationQuery参数必须设置为非空字符串 默认值: false testOnReturn #指明连接是否被空闲连接回收器(如果有)进行检验.如果检测失败,则连接将被从池中去除. #注意: 设置为true后如果要生效,validationQuery参数必须设置为非空字符串 默认值: false testWhileIdle=true 把最后一个置为true，就能确保放回去的idle连接是活的。

[iihero]

引用 2 楼 wy13tx 的回复:

这样每次用连接池中的连接都要查询一次数据库，太浪费资源了吧，有没有更好的办法？？？

楼主看来不太了解连接池的实现原理。

[wy13tx]

这样每次用连接池中的连接都要查询一次数据库，太浪费资源了吧，有没有更好的办法？？？

[wy13tx]

引用 3 楼 iihero 的回复:

[quote=引用 2 楼 wy13tx 的回复:] 这样每次用连接池中的连接都要查询一次数据库，太浪费资源了吧，有没有更好的办法？？？

楼主看来不太了解连接池的实现原理。 [/quote] 好的，我再看看吧，