LeakChecker: Practical Static Memory Leak Detection for Managed Languages

  • Authors:

  • Dacong Yan;Guoqing Xu;Shengqian Yang;Atanas Rountev

  • Affiliations:

  • Ohio State University;UC Irvine;Ohio State University;Ohio State University

  • Venue:
  • Proceedings of Annual IEEE/ACM International Symposium on Code Generation and Optimization
  • Year:
  • 2014

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Abstract

Static detection of memory leaks in a managed language such as Java is attractive because it does not rely on any leak-triggering inputs, allowing compile-time tools to find leaks before software is released. A long-standing issue that prevents practical static memory leak detection for Java is that it can be very expensive to statically determine object liveness in large applications. We present a novel (and the first practical) static leak detection technique that bypasses this problem by considering a common leak pattern. In many cases severe leaks occur in loops where, in each iteration, some objects created by the iteration are unnecessarily referenced by objects external to the loop. These unnecessary references are never used in later loop iterations. Based on this insight, we shift our focus from computing liveness, which is very difficult to achieve precisely and efficiently for large programs, to the easier goal of identifying objects that flow out of a loop but never flow back in. We formalize this analysis using a type and effect system and present its key properties. The analysis was implemented in a tool called LeakChecker and used to detect leaks in eight real-world programs, such as Eclipse, Derby, and log4j. LeakChecker not only identified known leaks, but also discovered new ones whose causes were unknown beforehand, while exhibiting a false positive rate suitable for practical use.