Refactoring sequential java code for concurrency via concurrent libraries

Parallelizing existing sequential programs to run ef-ficiently on multicores is hard. The Java 5 package java.util.concurrent (j.u.c.) supports writing con-current programs: much of the complexity of writing threads-safe and scalable programs is hidden in the library. To use this package, programmers still need to reengineer existing code. This is tedious because it requires chang-ing many lines of code, is error-prone because programmers can use the wrong APIs, and is omission-prone because pro-grammers can miss opportunities to use the enhanced APIs. This paper presents our tool, CONCURRENCER, which en-ables programmers to refactor sequential code into par-allel code that uses j.u.c. concurrent utilities. CONCUR-RENCER does not require any program annotations, although the transformations are very involved: they span multi-ple program statements and use custom program analysis. A find-and-replace tool can not perform such transforma-tions. Empirical evaluation shows that CONCURRENCER refac-tors code effectively: CONCURRENCER correctly identifies and applies transformations that some open-source developers overlooked, and the converted code exhibits good speedup.