(一)我的專案環境 ：javaweb專案採用c3p0連線池與mysql資料庫通訊，執行在centos7中的tomcat容器中。
症狀如下：
1.偶爾會報如下的錯誤（大致是一天一次，時間不定），此次插入資料庫失敗，但是重新插入就會成功。
2.我的c3p0配置如下

<c3p0-config >
	<default-config>
		<property name="user">root</property>
		<property name="password">密碼</property>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql:///資料庫名</propertty>
	</default-config>
</c3p0-config> 
 

3.報錯如下：
** BEGIN NESTED EXCEPTION **

java.net.SocketException
MESSAGE: Broken pipe (Write failed)

STACKTRACE:

java.net.SocketException: Broken pipe (Write failed)
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:111)
at java.net.SocketOutputStream.write(SocketOutputStream.java:155)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:2637)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1554)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1665)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3176)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1153)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1266)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
at org.apache.commons.dbutils.QueryRunner.query(QueryRunner.java:345)
at org.apache.commons.dbutils.QueryRunner.query(QueryRunner.java:287)
at dao.RechargeMoneyDao.getOrderIdByDeviceNum(RechargeMoneyDao.java:44)
at service.ShengKeService.getCheckInfo(ShengKeService.java:144)
at web.FindOrderServlet.doGet(FindOrderServlet.java:57)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1087)
at org.apache.coyote.AbstractProtocol$A$

** END NESTED EXCEPTION **

(二).解決方案

原因是出現了所謂的8小時問題，c3p0中預設的maxIdleTime為0，則表示連線永遠不會丟棄連線。
idleConnectionTestPeriod預設為0，表示不會去檢測連線池中連線的有效性。

所以需要修改配置如下

<c3p0-config >
	<default-config>
		<property name="user">賬號</property>
		<property name="password">密碼</property>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql:///資料庫名</property>
        <!-- 獲取connnection時測試是否有效 -->
		<property name="testConnectionOnCheckin">true</property>
		<!-- 自動測試的table名稱 -->
		<property name="automaticTestTable">C3P0TestTable</property>
		<!--設定為比wait_timeout小得多的值，可以防止連線失效  -->
		<property name="idleConnectionTestPeriod">18000</property>
		<!--設定為略低於wait_timeout的值，以防止傳送“陳舊”連線-->
		<property name="maxIdleTime">25000</property>
	</default-config>
</c3p0-config>