The C10k problem is still a puzzle for a programmer to find a way to solve it. Generally, developers deal with extensive I/O operations via thread, epoll, or kqueue to avoid their software waiting for an expensive task. However, developing a readable and bug-free concurrent code is challenging due to data sharing and job dependency. Even though some powerful tools, such as Valgrind, help developers to detect deadlock or other asynchronous issues, solving these problems may be time-consuming when the scale of software grows large. Therefore, many programming languages such as Python, Javascript, or C++ dedicated to developing better libraries, frameworks, or syntaxes to assist programmers in managing concurrent jobs properly. Instead of focusing on how to use modern parallel APIs, this article mainly concentrates on the design philosophy behind asynchronous programming patterns.