Concurrency debugging is an extremely important yet challenging problem that has been hampering developer productivity and software reliability in the multicore era. We have worked on this problem in the past eight years and have developed several effective methods and automated tools for helping developers debugging shared memory concurrent programs. This article discusses challenges in concurrency debugging and summarizes our research contributions in four important directions: concurrency bug reproduction, detection, understanding, and fixing. It also discusses other recent advances in tackling these challenges.