JPA与MySQL的连接引发“ TOO MANY CONNECTION”错误
[英]JPA Connection to MySQL Throws “TOO MANY CONNECTION” Error
问题描述
i tries to connect to mysql database through the Application-Server Glassfish and JPA. 
我尝试通过Application-Server Glassfish和JPA连接到mysql数据库。
My persistence.xml looks like this: 我的persistence.xml看起来像这样：
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1"
xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="WEBSERVIE-EJB"
transaction-type="JTA">
<jta-data-source>AVS_TWO</jta-data-source>
<properties>
<property name="eclipselink.ddl-generation" value="create-or-extend-tables" />
</properties>
</persistence-unit>
</persistence>
But if i trie that, the console of eclipse gives me the following error: 但是如果我尝试过，eclipse的控制台会给我以下错误：
Exception : Connection could not be allocated because: Data source rejected establishment of connection, message from server: "Too many connections"
Exception [EclipseLink-4019] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.DatabaseException Exception Description: Error while obtaining information about the database.
2016-08-03T13:09:47.479+0200|Schwerwiegend: Exception while deploying the app [WEB] 2016-08-03T13:09:47.479+0200|Schwerwiegend: Exception during lifecycle processing org.glassfish.deployment.common.DeploymentException: Exception [EclipseLink-4019] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.DatabaseException Exception Description: Error while obtaining information about the database.
The "max_connections" in mysql is set to 600. So that be enough. mysql中的“ max_connections”设置为600。这样就足够了。
Whats the problem? 有什么问题？
3 个解决方案
解决方案1
0 2016-08-03 23:53:41
解决方案2
0 2016-08-04 07:15:30
I connect to glassfish with JTA. 我用JTA连接到glassfish。 So i have configure a JDBC Connection Pool in Glassfish. 所以我已经在Glassfish中配置了JDBC连接池。 If i trigger the 'Ping' Button in glassfish for testing the connection, it works. 如果我触发了玻璃鱼中的“ Ping”按钮以测试连接，则它可以工作。
解决方案3
0 2016-08-19 11:37:09
https://dev.mysql.com/doc/refman/5.5/en/too-many-connections.html https://dev.mysql.com/doc/refman/5.5/en/too-many-connections.html
B.5.2.7 Too many connections B.5.2.7连接太多
If you get a Too many connections error when you try to connect to the mysqld server, this means that all available connections are in use by other clients. 如果在尝试连接到mysqld服务器时出现连接过多错误，则意味着所有可用连接正在被其他客户端使用。
The number of connections permitted is controlled by the max_connections system variable. 允许的连接数由max_connections系统变量控制。 The default value is 151 to improve performance when MySQL is used with the Apache Web server. 当MySQL与Apache Web服务器一起使用时，默认值是151，以提高性能。 (Previously, the default was 100.) If you need to support more connections, you should set a larger value for this variable. （以前，默认值为100。）如果需要支持更多连接，则应为此变量设置一个较大的值。
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