Grails 2.4 Mysql Validation Query not working on VPS

Question

I'm deploying a grails (2.4) application on tomcat7 (the OS is Ubuntu 14.04 server on VPS ). I use recommended settings to connect to DB (see below). I cannot see the validation query in the logs.

Note I have a test virtual machine on my PC - Ubuntu 14.04 desktop edition. In this environment the validation query is working and I'm not losing the connections. I can see the query logged into: /var/lib/mysql/test.log

Details

• the only difference which could cause the problem is: mysql_secure_installation

• these two environments are almost identical: one and the same: WAR file, same mysql and tomcat version ;

• SElinux is not enabled;
• MYSQL user has all privileges enabled;

I tried to change:

• remote login;

• remove external configuration;

• log tomcat, mysql and ubuntu logs - no errors and warnings;

Question - Is it possible monitor/log connection pool and errors/events related to it?

This is my externalized configuration file(placed in conf folder of grails app): config.properties :

dataSource.pooled = true
dataSource.dbCreate=update
dataSource.driverClassName=com.mysql.jdbc.Driver
dataSource.url=jdbc:mysql://localhost:3306/db
dataSource.username=user
dataSource.password=pass
dataSource.jmxEnabled = true
dataSource.initialSize = 5
dataSource.maxActive = 50
dataSource.minIdle = 5
dataSource.maxIdle = 25
dataSource.maxWait = 1000
dataSource.maxAge = 1000
dataSource.timeBetweenEvictionRunsMillis = 1000
dataSource.minEvictableIdleTimeMillis = 1000
dataSource.validationQuery = "SELECT 1"
dataSource.validationQueryTimeout = 30
dataSource.validationInterval = 1500
dataSource.testOnBorrow = true
dataSource.testWhileIdle = true
dataSource.testOnReturn = true
dataSource.jdbcInterceptors = "ConnectionState"
dataSource.defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED

I'm tracing sql connections with:

sudo mysqladmin -u root -p -i 5 processlist

and the result is:

+----+-------+-----------------+------------+---------+------+-------+------------------+
| Id | User  | Host            | db         | Command | Time | State | Info             |
+----+-------+-----------------+------------+---------+------+-------+------------------+
| 47 | test  | localhost:38977 | test       | Sleep   | 143  |       |                  |
| 48 | test  | localhost:38978 | test       | Sleep   | 143  |       |                  |
| 49 | test  | localhost:38979 | test       | Sleep   | 143  |       |                  |
| 50 | test  | localhost:38980 | test       | Sleep   | 143  |       |                  |
| 51 | test  | localhost:38981 | test       | Sleep   | 143  |       |                  |
| 52 | test  | localhost:38982 | test       | Sleep   | 143  |       |                  |
| 53 | test  | localhost:38983 | test       | Sleep   | 143  |       |                  |
| 54 | test  | localhost:38984 | test       | Sleep   | 143  |       |                  |
| 55 | test  | localhost:38985 | test       | Sleep   | 143  |       |                  |
| 56 | test  | localhost:38986 | test       | Sleep   | 138  |       |                  |
| 57 | root  | localhost       |            | Query   | 0    |       | show processlist |
+----+-------+-----------------+------------+---------+------+-------+------------------+

If the time out limit is reached: all connections are ended and tomcat gives an error:

+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 57 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

Thank you in advance!

Answer 1

You can add

        dataSource.logSql = true

to check your queries but in fact I'd rather check your mysql logs by one of these options: https://dev.mysql.com/doc/refman/5.6/en/server-logs.html

fe I still use oldschool tail -f /var/log/mysql/mysql.log