HikariPool-1 - Connection is not available, request timed out after 30000ms for very tiny load server

Question

I have a small Java application for testing purposes. I have moved to hikari recently. What I notice is that I keep getting this error.

java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30000ms.
java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30000ms.
at com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:602)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:195)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:145)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:85)

Below is my settings for the hikari initially.

 HikariConfig config = new HikariConfig();
            config.setJdbcUrl("jdbc:mysql://localhost:3306/****"); 
            config.setUsername("***"); 
            config.setPassword("*****");      
            config.setMaximumPoolSize(20);  

Hardly its being used my two devices and I ensure towards the end I do close it. So I don't know why it keep getting the error? What could be the issue or is there some settings which I need to change?

My hikari version is HikariCP-2.6.1.jar.

Answer 1

Your database is not obtaining connection within (30000 milliseconds that is default connectionTimeout property) because of network latency or some of the queries which are taking too long to execute(more than 30000 milliseconds).

Please try to increase value of property connectionTimeout.

YML configuration example:

spring:
  datasource:
    hikari:
      minimumIdle: 2
      maximumPoolSize: 10
      idleTimeout: 120000
      connectionTimeout: 300000
      leakDetectionThreshold: 300000

Java Config example:

HikariConfig config = new HikariConfig();
        config.setMaximumPoolSize(20);
        config.setConnectionTimeout(300000);
        config.setConnectionTimeout(120000);
        config.setLeakDetectionThreshold(300000);