For new projects use JDK 17+ with JetBrains Runtime, see Quick Start JDK 17+. trava-jdk-11-dcevm is not updated anymore.

Install

Use OpenJDK Hotswap instead of standard JDK-11. Download latest release of trava-jdk-11-dcevm, unpack it and set JAVA_HOME to it’s location (or add it as JDK to your IDE).

Configure

  1. Run your application with the option -XX:HotswapAgent=fatjar. Without it the agent is not loaded (the default is disabled).
  2. This JDK contains an old agent (1.4.1) in lib/hotswap. Replace <JDK>/lib/hotswap/hotswap-agent.jar with the latest release (keep the file name hotswap-agent.jar), or use -XX:HotswapAgent=external -javaagent:/path/to/hotswap-agent.jar.
  3. (optional) create a file named “hotswap-agent.properties” inside your resources directory, see available properties and default values: https://github.com/HotswapProjects/HotswapAgent/blob/master/hotswap-agent-core/src/main/resources/hotswap-agent.properties
  4. (optional) in case you are not using autoHotswap=true and therefore not using the hotswapping mechanism provided by HotswapAgent, you may want to add -Xlog:redefine+class*=info as an additional JVM argument in order to get feedback about reloaded classes.

Run

  1. start the application in debug mode, check that the agent and plugins are initialized correctly:

     HOTSWAP AGENT: 9:49:29.548 INFO (org.hotswap.agent.HotswapAgent) - Loading Hotswap agent - unlimited runtime class redefinition.
 HOTSWAP AGENT: 9:49:29.725 INFO (org.hotswap.agent.config.PluginRegistry) - Discovered plugins: [org.hotswap.agent.plugin.hotswapper.HotswapperPlugin, org.hotswap.agent.plugin.jvm.AnonymousClassPatchPlugin, org.hotswap.agent.plugin.hibernate.HibernatePlugin, org.hotswap.agent.plugin.spring.SpringPlugin, org.hotswap.agent.plugin.jetty.JettyPlugin, org.hotswap.agent.plugin.tomcat.TomcatPlugin, org.hotswap.agent.plugin.zk.ZkPlugin, org.hotswap.agent.plugin.logback.LogbackPlugin]
 ...
 HOTSWAP AGENT: 9:49:38.700 INFO (org.hotswap.agent.plugin.spring.SpringPlugin) - Spring plugin initialized - Spring core version '3.2.3.RELEASE'

  2. save a changed resource and/or use the HotSwap feature of your IDE to reload changes