I. What is DoS? DoS is short for Denial of Service, which means denial of service. The attack that causes DoS is called a DoS attack, and its purpose is to make the computer or network unable to provide normal services. Denial of Service exists on various web services, this web service can be implemented in c, c++, or go, java, php, python, and other languages. II. Status of Java DoS In various open source and closed source java system products, we often see announcements about DoS defects, most of which are CPU exhaustion type or business offload type DoS.