[POOL-363] Evictor Thread prevents Spring Context shutdown in standalone app

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.3, 2.5.0, 2.6.0, 2.6.1
• Fix Version/s: 2.6.2
• Labels: pull-request-available

Environment

Java 1.8.0_171

• Assignee: Unassigned
• Reporter: Josh Landin
• Created: 26/Mar/19 18:52
• Updated: 01/Apr/19 16:41
• Resolved: 29/Mar/19 23:42

Description

Given a DBCP2 connection pool configured in a Spring Application context with the POOL evictor thread enabled, a standalone main() application hangs on shutdown. Example below:

Maven pom.xml:

  <dependencies>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-dbcp2</artifactId>
      <version>2.6.0</version><!-- Uses commons-pool2 : 2.6.1 -->
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.15</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.1.5.RELEASE</version>
    </dependency>
  </dependencies>

MainTest.java:

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

import org.apache.commons.dbcp2.BasicDataSource;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

public class MainTest
{
  @Configuration
  public static class Config 
  {
    @Bean
    public DataSource getBasicDataSource()
    {
      BasicDataSource d = new BasicDataSource();
      d.setUrl("jdbc:mysql://localhost:3306/anydb");
      d.setUsername("myuser");
      d.setPassword("mypass");
      d.setTimeBetweenEvictionRunsMillis(1000); // Turn on Evictor Thread.
      return d;
    }
  }

  public static void main(String[] args)
  {
    AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class);
    ctx.registerShutdownHook(); // Ensures context.close() on JVM shutdown.
    
    try(
        Connection conn = ctx.getBean(BasicDataSource.class).getConnection(); 
        Statement stmt = conn.createStatement();
        ResultSet result = stmt.executeQuery("SELECT 1");
    )
    {
      int records = result.last() ? result.getRow() : 0;
      System.out.println("Records: "+records);
    }
    catch(SQLException e)
    {
      e.printStackTrace();
    }
    System.out.println("End.");
  }
}

The issue is not present when turning off the eviction thread by setting timeBetweenEvictionRunsMillis to -1.

Jconsole thread summary attached for reference.

Issue Links

• links to: GitHub Pull Request #20