Convoider: A Concurrency Bug Avoider Based on Transparent Software Transactional Memory

Abstract

Software transactional memory is an effective mechanism to avoid concurrency bugs in multi-threaded programs. However, two problems hinder the adoption of traditional such systems in wild world: high human cost for equipping programs with transaction functionality and low compatibility with I/O calls and conditional variables. This paper presents Convoider to try to solve these problems. By intercepting inter-thread operations and designating code among them as transactions in each thread, Convoider automatically transactionalizes target programs without any source code modification and recompiling. By saving/restoring stack frames and CPU registers on beginning/aborting a transaction, Convoider makes execution flow revocable. By turning threads into processes, leveraging virtual memory protection and customizing memory allocation/deallocation, Convoider makes memory manipulations revocable. By maintaining virtual file systems and redirecting I/O operations onto them, Convoider makes I/O effects revocable. By converting lock/unlock operations to no-ops, customizing signal/wait operations on condition variables and committing memory changes transactionally, Convoider makes deadlocks, data races and atomicity violations impossible. Experimental results show that Convoider succeeds in transparently transactionalizing twelve real-world applications and perfectly avoid 94% of thirty-one concurrency bugs used in our experiments. This study can help efficiently transactionalize legacy multi-threaded applications and effectively improve the runtime reliability of them.