On the Prevalence of Function Side Effects in General Purpose Open Source Software Systems

Abstract

A study that examines the prevalence and distribution of function side effects in general-purpose software systems is presented. The study is conducted on 19 open source systems comprising over 9.8 Million lines of code (MLOC). Each system is analyzed and the number of function side effects is determined. The results show that global variables modification and parameters by reference are the most prevalent side effect types. Thus, conducting accurate program analysis for many adaptive changes processes (e.g., automatic parallelization to improve their parallelizability to better utilize multi-core architectures) becomes very costly or impractical to conduct. Analysis of the historical data over a seven-year period for 10 systems show that there is a relatively large percentage of affected functions over the lifetime of the systems. The trend is flat in general, therefore posing further problems for inter-procedural analysis.