How do I determine the origin of database connection pool leaks?

Hi all,

I have a tomcat9 web application that is leaking connections, and I need to detect where the leaks are occurring. This is surprisingly difficult.

The leak is reproducible, and occurs in a controlled test environment, so the vast majority of advice out there about monitoring database connections isn't useful - I know there is a leak. The codebase is large, so the "look at the codebase" advice doesn't work.

The exceptions I get tell me all about the straw that broke the camel's back, but none of that is useful - what I need to know at that point is what else is on the camel's back.

Is there a mechanism that exists where you can trigger a dump of the stack traces of all database connections currently open and where they were opened? Remember - in my case this is a reproducible leak in a controlled test environment, so I don't have the problem of a live system or filtering out noise.

This isn't working for me, I see no stack traces related to abandoned connections:

    <Resource auth="Container" driverClassName="org.postgresql.Driver" factory="org.apache.tomcat.dbcp.dbcp2.BasicDataSourceFactory" logAbandoned="true" maxIdle="5" maxTotal="5" maxWaitMillis="10000" name="" password="" type="javax.sql.DataSource" url="" username="" removeAbandonedOnBorrow="true" removeAbandoned="true" removeAbandonedTimeout="10" />

Is there a breakpoint I can stop the code at, or a signal I can send?

Regards,
Graham
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