A system and method supports dynamic thread pool sizing suitable for use in multi-threaded processing environment such as a distributed data grid. Dynamic thread pool resizing utilizes measurements of thread pool throughput and worker thread utilization in combination with analysis of the efficacy of prior thread pool resizing actions to determine whether to add or remove worker threads from a thread pool in a current resizing action. Furthermore, the dynamic thread pool resizing system and method can accelerate or decelerate the iterative resizing analysis and the rate of worker thread addition and removal depending on the needs of the system. Optimizations are incorporated to prevent settling on a local maximum throughput. The dynamic thread pool sizing/resizing system and method thereby provides rapid and responsive adjustment of thread pool size in response to changes in work load and processor availability.