JDBC CommunicationsException与MySQL数据库

Question

I'm having a little trouble with my MySQL- Connection- Pooling. This is the case:

Different jobs are scheduled via Quartz. All jobs connect to different databases which works fine the whole day while the nightly scheduled jobs fail with a CommunicationsException...

Quartz-Jobs:

Job1 runs 0 0 6,10,14,18 * * ?
Job2 runs 0 30 10,18 * * ?
Job3 runs 0 0 5 * * ?

As you can see the last job runs at 18 taking about 1 hour to run. The first job at 5am is the one that fails. I already tried all kinds of parameter-combinations in my resource config this is the one I am running right now:

<!-- Database 1 (MySQL) -->
<Resource
 auth="Container"
 driverClassName="com.mysql.jdbc.Driver"
 maxActive="100"
 maxIdle="30"
 maxWait="10000"
 removeAbandoned="true"
 removeAbandonedTimeout="60"
 logAbandoned="true"
 type="javax.sql.DataSource"
 name="jdbc/appDbProd"
 username="****"
 password="****"
 url="jdbc:mysql://127.0.0.1:3306/appDbProd?autoReconnect=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"
 testWhileIdle="true"
 testOnBorrow="true"
 testOnReturn="true"
 validationQuery="SELECT 1"
 timeBetweenEvictionRunsMillis="1800000"
/>

<!-- Database 2 (MySQL) -->
<Resource
 auth="Container"
 driverClassName="com.mysql.jdbc.Driver"
 maxActive="100"
 maxIdle="30"
 maxWait="10000"
 removeAbandoned="true"
 removeAbandonedTimeout="60"
 logAbandoned="true"
 type="javax.sql.DataSource"
 name="jdbc/prodDbCopy"
 username="****"
 password="****"
 url="jdbc:mysql://127.0.0.1:3306/prodDbCopy?autoReconnect=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"
 testWhileIdle="true"
 testOnBorrow="true"
 testOnReturn="true"
 validationQuery="SELECT 1"
 timeBetweenEvictionRunsMillis="1800000"
/>
<!-- Database 3 (MSSQL)-->
<Resource
 auth="Container"
 driverClassName="net.sourceforge.jtds.jdbc.Driver"
 maxActive="30"
 maxIdle="30"
 maxWait="100"
 removeAbandoned="true"
 removeAbandonedTimeout="60"
 logAbandoned="true"
 name="jdbc/catalogDb"
 username="****"
 password="****"
 type="javax.sql.DataSource"
 url="jdbc:jtds:sqlserver://127.0.0.1:1433;databaseName=catalog;useNdTLMv2=false"
 testWhileIdle="true"
 testOnBorrow="true"
 testOnReturn="true"
 validationQuery="SELECT 1"
 timeBetweenEvictionRunsMillis="1800000"
/>

For obvious reasons I changed IPs, Usernames and Passwords but they can be assumed to be correct, seeing that the application runs successfully the whole day.

The most annoying thing is: The first job that runs first queries Database2 successfully but fails to query Database1 for some reason (CommunicationsException):

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 39,376,539 milliseconds ago. The last packet sent successfully to the server was 39,376,539 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.

Any ideas? Thanks!

Answer 1

如前所述，在连接池上启用连接验证。

Answer 2

I get this error when a connection is left idle for a while. Do your jobs stop hitting the DB at some point, then run some queries?

It also happens when there's a link failure, you might want to check with your network team if the connection doesn't drop.

Answer 3

I have run into a similar issue using Oracle, and JDBC. It ended up I was consuming all of the connections that were available to the database, and I wasn't relinquishing any of them and my code would just halt or timeout. Take a look at how you are handling your connections in your code.