1) Login to glassfish admin http://localhost:4848
2) Go to the Application server and select the JVM Setting
3) Be sure to checked the debug checkbox
4) Save the changed and restart server required
5) Right click the project and select debug as, and Debug configurations.
6) Last, select Remote Java Application and change your host to localhost and port to 9009
7) And happy debugging 🙂
Configure debugging liferay from eclipse