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I am facing such annoying problem,
running on Tomcat 6 and MySQL using TomcatJDBC Lib.

com.mysql.jdbc.CommunicationsException:

Communications link failure due to underlying exception: 

** BEGIN NESTED EXCEPTION ** java.io.EOFException STACKTRACE: java.io.EOFException at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1934) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2380) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2909) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1600) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1695) at com.mysql.jdbc.Connection.execSQL(Connection.java:3026) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1137) at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1231)

After some time (20sh mins) this occurs, all connections to db seems to expire.

autoReconnect=true" validationQuery="Select 1"

Everything is set.
I do handle reconnect to database, and it works fine, but huge log files are bad, i cant either handle this exception to make it silent. Also this type of "fixing" isn't right solution. Is there any way to:
a) Handle this exception silently
b) Fix this issue (i do not have any firewall that i know of) (dont have access to my.cnf for mysql configuration)

Also having this problem on Tomcat 5 with Apache jConnector on totaly different application, without any firewalls that could drop a connection.

(Catching EOFException or CommunicationsException on method that does invoke connection doesn't help of course.)

Thanks in advance.

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  • What is your JDBC URL? I assume autoReconnect=true is part of the URL? Where are you defining the validationQuery? Commented Oct 26, 2011 at 1:33
  • 1
    url="jdbc:mysql://adress/dbName?autoReconnect=true" validationQuery="Select 1" Commented Oct 26, 2011 at 16:05
  • Where is the validationQuery defined @BShip? Commented Oct 26, 2011 at 16:44
  • in context.xml the same line wheres url<Resource name="jdbc/mydb" auth="Container" type="javax.sql.DataSource" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" maxActive="30" maxIdle="10" maxWait="-1" username="xxx" password="xxx" driverClassName="com.mysql.jdbc.Driver" url="jdbc:mysql://server/mydb?autoReconnect=true" validationQuery="Select 1"/> Commented Oct 26, 2011 at 17:03
  • Sorry, I'm ignorant of Tomcat's configs. I don't see a problem with this. Looks to me that you are doing the right thing. Best of luck. Commented Oct 26, 2011 at 17:09

3 Answers 3

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2

a) Stop MySQL db server and application server (Tomcat or else).

b) Mysql settings: This should be done in "my.ini" file under mysql folder.

wait_timeout =1200 (i.e 20 min – Keep same time of your firewall OR any other third party software)

You can set it DB level by above query. set wait_timeout =1200;

View settings by above query Show variables like 'wait_timeout' ;

c) Add two properties in “Torque.properties” file.

minEvictableIdleTimeMillis A the time in millisecond a connection can stay idle in the pool

 torque.dsfactory.csa.pool.minEvictableIdleTimeMillis = 1100000

#timeBetweenEvictionRunsMillis A the time in millisecond between the run of the eviction thread; must be greater than 0; default to -1

 torque.dsfactory.csa.pool.timeBetweenEvictionRunsMillis = 2000 d) Start application and db server
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2

Check the status of MYSQL by using command /s now check the port number that you have mentioned in the code and that should match with MYSQL port if port numbers are different change it

(jdbc:mysql://localhost:3306/mrt) in this example my port number is 3306

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you need to set MaxIdle and Timeout property in server.xml file in resource.

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