Tomcat's connection pool opens only 20 connections to mysql

Question

I have a java application with following line in context.xml

<Resource 
    driverClassName="com.mysql.jdbc.Driver" 
    maxActive="100" 
    maxIdle="30" 
    initialSize="10" 
    maxWait="7000" 
    name="jdbc/app" 
    password="pass" 
    type="javax.sql.DataSource" 
    url="jdbc:mysql://dbhost:3306/dbname?autoReconnect=true" 
    username="user" 
    validationQuery="SELECT 1" 
    removeAbandoned="true" 
    removeAbandonedTimeout="30" 
    logAbandoned="true" 
/>

In mysql 'show variables' tells me that max_connections is 151.

Still,

use information_schema;
select count(*) from processlist where User = 'user';

never shows me more than 20 connections. On tomcat's catalina.out -log I get

Caused by: org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot get a connection, pool exhausted
        at org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:103)
        at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:540)
        at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:113)
        at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79)

What should I check for to find the problem?

score 1 · Answer 1 · answered Aug 14 '11 at 00:32

1

And check whether the application is closing connections properly, this is the programmers stuff to do, but still a common error.

answered Aug 14 '11 at 00:32

flo

66
1

score 0 · Answer 2 · answered Dec 22 '09 at 15:36

0

I'm not sure it is a Tomcat problem, check to see if MySQL is limiting the number of connections.

answered Dec 22 '09 at 15:36

Joshua

779
1
9
18

score 0 · Answer 3 · answered Dec 22 '09 at 19:05

0

Also check MySQL's max_user_connections variable.

answered Dec 22 '09 at 19:05

ahanson

1,674
2
15
21

Tomcat's connection pool opens only 20 connections to mysql

3 Answers3