Effect of Fault Distribution and Execution Patterns on Fault Exposure in Software: A Simulation Study

Execution patterns and fault distribution characteristics of a program will aaect the failure process and thus reliability estimates. The failure process of a software system is innuenced by many factors, and traditional software reliability engineering has found it diicult to isolate the eeect of each individual factor. A simulation approach is used to investigate the eeects of fault distribution, execution pattern and program structure on software reliability estimates. A reliability simulation environment (RSIM) is extended by introducing variable fault distribution patterns in its code generation phase. Flow control points allow varying the execution frequency of diierent parts of a program. The simulation results show that fault distribution patterns and execution patterns have dramatic eeects on fault exposure rate. If the fault distribution is non-uniform, a non-uniform code execution exposes faults more eeciently and eeectively than uniform execution. Results also show that the structure of a program aaects fault exposure rate and testing time required.