Recently we deployed our production application on a Tomcat 8.0.14 web server. We are using the Tomcat JDBC Connection pool against MySQL 5. Our web application uses Spring (3.2.11.RELEASE) /Hibernate (3.6.10.Final) for transaction management. We are using a Cent OS 6 linux server in the cloud running the 2.6.32-504 kernel. We're using the 1.8.0_25 jdk.
Ever since deployment, we've noticed that a couple of times per day, when Spring is attempting to prepare/open a new JDBC Connection, the thread in question times out for about 15 minutes, and then resumes as if everything is fine. The line that appears to be hanging from the hibernate side is factory.getConnectionProvider().getConnection(), which I think simply asks for a connection from the pool. The following options are defined in the Resource definition: auth="Container" factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" type="javax.sql.DataSource" driverClassName="com.mysql.jdbc.Driver" maxActive=500 maxIdle=55 maxWait=15000 validationQuery="Select 1" testOnBorrow="true" defaultAutoCommit="false" At this time of year, our user load peaks around 150, so we shouldn't be coming close to the maxActive defined. MySql is configured to allow for 1010 maximum connections (we have two Tomcat instances that point to it, configured similarly) This application has ran for years without a problem against a Tomcat 6 instance, but after moving to Jdk 8 and Tomcat 8, we're seeing this 15 minute wait. Any ideas on what could cause this sort of thing, and as there additional logging we could turn on to try and figure out what is happening inside the pool to make it wait so long?
