com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException：连接太多

Question

我的简单网络应用程序在浏览网站时有时会崩溃，我从日志中得到的错误消息如下所示。我完全不知道是什么原因造成的，并且非常感谢任何能引导我走向正确方向的提示。

HTTP Status 500 - org.hibernate.exception.JDBCConnectionException: Cannot open connection

输入异常报告

message org.hibernate.exception.JDBCConnectionException: Cannot open connection

description The server encountered an internal error that prevented it from fulfilling this request.

exception
org.apache.jasper.JasperException: org.hibernate.exception.JDBCConnectionException: Cannot open connection
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:549)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

根本原因

org.hibernate.exception.JDBCConnectionException: Cannot open connection
    org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:97)
    org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
    org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
    org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449)
    org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
    org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
    org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1573)
    org.hibernate.loader.Loader.doQuery(Loader.java:696)
    org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
    org.hibernate.loader.Loader.doList(Loader.java:2228)
    org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2125)
    org.hibernate.loader.Loader.list(Loader.java:2120)
    org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:118)
    org.hibernate.impl.SessionImpl.list(SessionImpl.java:1596)
    org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:306)
    com.html.XmlSetting.getListOfhtml_connect(XmlSetting.java:55)
    com.html.XmlSetting.removeXml(XmlSetting.java:121)
    com.html.MarginSetting.removeXml(MarginSetting.java:291)
    org.apache.jsp.check_jsp._jspService(check_jsp.java:183)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

根本原因

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections
    sun.reflect.GeneratedConstructorAccessor153.newInstance(Unknown Source)
    sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    java.lang.reflect.Constructor.newInstance(Constructor.java:532)
    com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
    com.mysql.jdbc.Util.getInstance(Util.java:381)
    com.mysql.jdbc.SQLError.createSQLException(SQLError.java:985)
    com.mysql.jdbc.SQLError.createSQLException(SQLError.java:957)
    com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3376)
    com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3308)
    com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:894)
    com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:3808)
    com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1256)
    com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2032)
    com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:729)
    com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    sun.reflect.GeneratedConstructorAccessor145.newInstance(Unknown Source)
    sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    java.lang.reflect.Constructor.newInstance(Constructor.java:532)
    com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
    com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
    com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:283)
    java.sql.DriverManager.getConnection(DriverManager.java:620)
    java.sql.DriverManager.getConnection(DriverManager.java:169)
    org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:133)
    org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
    org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
    org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
    org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1573)
    org.hibernate.loader.Loader.doQuery(Loader.java:696)
    org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
    org.hibernate.loader.Loader.doList(Loader.java:2228)
    org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2125)
    org.hibernate.loader.Loader.list(Loader.java:2120)
    org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:118)
    org.hibernate.impl.SessionImpl.list(SessionImpl.java:1596)
    org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:306)
    com.html.XmlSetting.getListOfhtml_connect(XmlSetting.java:55)
    com.html.XmlSetting.removeXml(XmlSetting.java:121)
    com.html.MarginSetting.removeXml(MarginSetting.java:291)
    org.apache.jsp.check_jsp._jspService(check_jsp.java:183)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

我正在使用 Apache Tomcat 7

hibernate.cfg.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>

        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/htmlcleaner</property>
        <property name="hibernate.connection.password">root</property>
        <property name="hibernate.connection.username">root</property>

        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="hibernate.connection.zeroDateTimeBehavior">convertToNull</property>

        <property name="connection.pool_size">1000</property>

       <!--  <property name="show_sql">true</property> -->
        <mapping class="com.model.html_connect"/>

    </session-factory>
</hibernate-configuration>

Answer 1

看起来您正在大量泄漏连接。完成后是否关闭休眠会话？

您也可以尝试摆弄hibernate.connection.release_mode，默认情况下，它设置为自动，当您关闭会话时它将释放连接。但是，您也可以在此处选择使用 after_transaction 或 after_statement （当它释放两者的连接时，这是不言自明的：P）。

话虽如此，您确实需要找出泄漏的位置:)

Answer 2

可能的原因是您的 Web 应用程序可能存在连接泄漏或连接池非常小，导致当前所有打开的连接都在使用中，无法获取新连接。

我不确定Tomcat，但在JBoss中，我们通常指数据源文件，您可以将连接池大小设置为

   <max-pool-size>80</max-pool-size>

您甚至可以登录到 Tomcat 的管理控制台，并在遇到此异常时检查实际使用了多少连接。管理控制台将为您提供有史以来创建的最大连接对象以及与连接池相关的各种其他信息。

Answer 3

它清楚地看到hibernate无法创建或打开与数据库的连接，可能有很多原因

1. 您在使用会话后未在程序中关闭会话
2. 连接池很小，访问池的线程过多。

请粘贴您的配置和异常点程序

添加

<property name="hibernate.connection.release_mode">on_close</property>

属性并调用 session.close();在你的方法结束时