c3p0 threadLocal 报错：too many connection

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c3p0 threadLocal 报错：too many connection10

code="java"]public class DBUtil {
private static final ThreadLocal<Connection> threadLocal = new ThreadLocal<Connection>();

/**
* 取得数据库连接
* @return
*/
public static Connection getConnection() {
Connection conn = null;
conn = threadLocal.get();
if(conn==null) {
conn = ConnectionManager.getInstance().getConn();
threadLocal.set(conn);
}
return conn;
}

public static void closeConn() {
Connection conn = threadLocal.get();
try {
if(conn!=null && !conn.isClosed()) {
conn.close();
threadLocal.remove();
}
} catch (SQLException e) {
e.printStackTrace();
}
}

public static void main(String args[]) {
for(int i=0;i<30;i++) {
Connection conn = getConnection();
closeConn();
System.out.println(i+"="+conn);
}
}
}

public class ConnectionManager {
	private static ConnectionManager instance;
	private ConnectionManager(){}
	
	public synchronized Connection getConn() {
		Connection conn = null;
		ComboPooledDataSource ds = new ComboPooledDataSource("userApp");
		
		try {
			conn = ds.getConnection();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}
	
	public static ConnectionManager getInstance() {
		if(instance==null) {
			instance = new ConnectionManager();
		}
		return instance;
	}
	
}

c3p0配置：

<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/examtest?useUnicode=true&amp;characterEncoding=utf-8</property>
		<property name="user">root</property>
		<property name="password">root</property>
		<property name="acquireIncrement">10</property>
		<property name="acquireRetryAttempts">30</property>
		<property name="initialPoolSize">10</property>
		<property name="minPoolSize">10</property>
		<property name="maxPoolSize">40</property>
		<property name="checkoutTimeout">1000</property>
		<property name="idleConnectionTestPeriod">18000</property>
		<property name="maxIdleTime">25000</property>

[color=red]一运行就报错：[/color]
java.sql.SQLException: Data source rejected establishment of connection,  message from server: "[color=red]Too many connections[/color]"
	at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1018)
	at com.mysql.jdbc.Connection.createNewIO(Connection.java:2568)
	at com.mysql.jdbc.Connection.<init>(Connection.java:1485)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:266)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:119)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:143)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:132)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.initializeAutomaticTestTable(C3P0PooledConnectionPoolManager.java:772)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.createPooledConnectionPool(C3P0PooledConnectionPoolManager.java:696)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.getPool(C3P0PooledConnectionPoolManager.java:257)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.getPool(C3P0PooledConnectionPoolManager.java:271)
	at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
	at com.tom.util.ConnectionManager.getConn(ConnectionManager.java:17)
	at com.tom.util.DBUtil.getConnection(DBUtil.java:19)
	at com.tom.util.DBUtil.main(DBUtil.java:115)
28=null
          
          
            
            问题补充：只能取得10个连接，第11个就开始报错

2012年11月06日 19:10

ncs123
4
0 0 7

1个答案按时间排序按投票排序

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1.可能是mysql的max connections设置的问题
2.可能是多次insert,update操作没有关闭session,需要在spring里配置transaction支持。

解决:
1.修改tomcat里的session 的time-out时间减少为20,(不是必改项)
2.对处理量大的对数据库insert或update的操作提供transaction支持.

=======================================
下面的是解决办法：
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections"

原因：

因为你的mysql安装目录下的my.ini中设定的并发连接数太少或者系统繁忙导致连接数被占满

解决方式：

打开MYSQL安装目录打开MY.INI找到max_connections（在大约第93行）默认是100 一般设置到500～1000比较合适，重启mysql,这样1040错误就解决啦。
max_connections=1000

一定要重新启动MYSQL才能生效

CMD->

net stop mysql

net start mysql

关于改变innodb_log_file_size后无法启动mysql的问题

innodb_buffer_pool_size=768M
innodb_log_file_size=256M
innodb_log_buffer_size=8M
innodb_additional_mem_pool_size=4M
innodb_flush_log_at_trx_commit=0
innodb_thread_concurrency=20
以上是对innodb引擎的初步优化, 发现是更新innodb_log_file_size=256M时候出现了问题，只要加上这个就无法启动,

后来才知道原来要STOP服务先，然后再删除原来的文件………
打开/MySQL Server 5.5/data

删除ib_logfile0, ib_logfile1........ib_logfilen