JavaMelody JDBC Graph not working Tomcat 8.8 and mysql DB - java-melody

Question

I have configured javamelody 1.86.0 on Tomcat 8.8 and all the other metrics are captured except from the JDBC. Below are the config I have on the Tomcat application:
Context.xml:
<ResourceLink type="javax.sql.DataSource"
name="jdbc/LocalAPIDB"
global="jdbc/APIDB"/>
Server.xml:
<Resource type="javax.sql.DataSource"
name="jdbc/APIDB"
factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/apiDB"
username="xxxx"
password="xxxxx"
initialSize="340"
maxActive="3770"
maxIdle="2330"
minIdle="890"
testOnBorrow="true"
validationQuery="SELECT 1"
validationInterval="30000"
timeBetweenEvictionRunsMillis="5000"
minEvictableIdleTimeMillis="60000"
removeAbandoned="true"
removeAbandonedTimeout="60"
abandonWhenPercentageFull="0"
logAbandoned="true"
jdbcInterceptors="org.apache.tomcat.jdbc.pool.interceptor.ConnectionState;
org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer;org.apache.tomcat.jdbc.pool.interceptor.ResetAbandonedTimer"/>
On mbeans I can see there are active connections but on the graph nothing is captured.
JDBC Graph
MBeans
Debugging Logs

Answer 1

I suggest that you move the Resource from server.xml to the xml context file of the webapp (conf/Catalina/localhost/MpesaIntegrations.xml) and that you remove the ResourceLink.
So the xml context file of the webapp is like this:
<?xml version="1.0" encoding="UTF-8" ?>
<Context>
<Resource type="javax.sql.DataSource"
name="jdbc/LocalAPIDB"
factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/apiDB"
username="xxxx"
password="xxxxx"
initialSize="340"
maxActive="3770"
maxIdle="2330"
minIdle="890"
testOnBorrow="true"
validationQuery="SELECT 1"
validationInterval="30000"
timeBetweenEvictionRunsMillis="5000"
minEvictableIdleTimeMillis="60000"
removeAbandoned="true"
removeAbandonedTimeout="60"
abandonWhenPercentageFull="0"
logAbandoned="true"
jdbcInterceptors="org.apache.tomcat.jdbc.pool.interceptor.ConnectionState;org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer;org.apache.tomcat.jdbc.pool.interceptor.ResetAbandonedTimer"
/>
</Context>
And/or, if that's not enough, you probably have a listener or filter in your webapp that is getting and keeping in cache the DataSource. In that case, put the javamelody listener and filter near the top of your WEB-INF/web.xml file.

Answer 2

For anybody scratching their head trying to find out why JavaMelody won't show database stats such as 'active JDBC connections', I finally solved it by doing 2 things. Note that in my case I'm using Java 11 running Apache Tomcat 9 hosting an Apache Derby 10.15.2 database:
Setting up the database in the 'apache-tomcat-9.0.52\conf\context.xml' file eather than in java code in my webapp. I think this made the database associated with the JNDI resource name so JavaMelody could see it. I added this XML to that context.xml file:
<Resource name="jdbc/DatabaseJNDIResourceName"
auth="Container"
type="javax.sql.DataSource"
driverClassName="org.apache.derby.jdbc.EmbeddedDriver"
url="jdbc:derby:../DatabaseName;"
username="someuser"
password="s3cret"
/>
Then you can get the DataSource in your webapp java code using:
InitialContext initialContextJNDI = new InitialContext();
DataSource dataSource = (DataSource)initialContextJNDI.lookup("java:comp/env/jdbc/DatabaseJNDIResourceName");
Note that a method to detect a potential JNDI resource name problem is to see if the resource name shows up in JavaMelody by navigating to the page 'JNDI tree' at the bottom, linked here http://localhost:8080/monitoring?part=jndi
Inserting the web.xml code referred to here. Interestingly, when that XML code was left out, javamelody would still run but it didn't report JDBC-related data.
<filter>
<filter-name>javamelody</filter-name>
<filter-class>net.bull.javamelody.MonitoringFilter</filter-class>
<async-supported>true</async-supported>
</filter>
<filter-mapping>
<filter-name>javamelody</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>ASYNC</dispatcher>
</filter-mapping>
<listener>
<listener-class>net.bull.javamelody.SessionListener</listener-class>
</listener>
Another thing, even after these fixes finally solved the problem and made JavaMelody aware of my database, I didn't immediately notice since the graphs barely change if your database queries are fast. I only confirmed that the database stats were being logged after executing a long SQL query and updating the 'opened jdbc connections' page, linked at the bottom of the javamelody stats page here, which showed one single connection while the database took a few seconds to process the large (1 million row table) query http://localhost:8080/monitoring?part=connections