Fundamentals of software aging

Software aging consists in the increase of the failure rate or in the performance degradation of a system as it executes, which can be due to the accumulation of errors in the system state and to the consumption of resources such as physical memory. Software aging represents a real issue in long running applications, such as servers or telecom systems. This chapter provides fundamental concepts and definitions related to software aging. In particular, the concepts of aging-related bugs, aging-related failure, and aging effects are discussed in order to pave the way for the rest of the book. Examples of software aging in real-world systems are also discussed to motivate the reader to understand the potential impact of this phenomenon. At the end of this chapter, software aging research is contextualized in the wider field of performance engineering research and, in particular, in the field of software testing and monitoring.