You can quickly monitor HikariCP connection pool metrics without enabling Micrometer or OpenTelemetry. Just follow these two simple steps:
1. Enable Debug Logging in logback-spring.xml. Add one of the following logging configurations:
For general Hikari pool logging:
<logger name="com.zaxxer.hikari.pool.HikariPool" level="DEBUG" />For more detailed logging:
<logger name="com.zaxxer.hikari" level="DEBUG" />2. Set the Housekeeping Interval via VM Option Set the following JVM option to adjust the logging frequency (default is 30s; this reduces it to 5 seconds):
-Dcom.zaxxer.hikari.housekeeping.periodMs=5000
Example Log Output
Once enabled, you’ll start seeing logs like this:
2025-03-29 16:30:07,869 DEBUG c.z.h.p.HikariPool[HikariPool-1 housekeeper] - HikariPool-1 - Pool stats (total=2, active=0, idle=2, waiting=0)
Breakdown of Pool Stats:
- total=2 - The total number of connections in the pool (both active and idle).
- active=0 - The number of connections currently in use (0 means no connections are being used).
- idle=2 - The number of available (idle) connections that are not in use.
- waiting=0 - The number of threads waiting for a connection (0 means no requests are waiting).
By enabling this, you get real-time insights into your connection pool without additional monitoring tools.
