Purify: Fast detection of memory leaks and access errors

This paper describes Purifyru, a software testing and quality assurance Ool that detects memory leaks and access erors. Purify inserts additional checking instructions directly into the object code produced by existing compilers. These instructions check every memory read and write performed by the program-under-test and detect several types of access errors, such as reading uninitialized memory or witing to freed memory. Purify inserts checking logic into all of the code in a program, including third-party and vendor object-code libraries, and verifies system call interfaces. In addition, Purify tracks memory usage and identifies individual memory leals using a novel adaptation of garbage collection techniques. Purify produces tandard executable files compatible with existing debuggers, and currently runs on Sun Microsystems ' SPARC family of workstations. Purify's neafly-comprehensive memory access checking slows the target program down typically by less than a facor of three and has resulted in significantly more reliable software for several development goups. L