The scalability problem, which presents that the performance of a multi-threaded program keeps constant or is degraded as more threads are involved when running on many-core processors, still poses challenges to OS designers and application programmers. Previous research work has demonstrated that removing bottlenecks associated with synchronization and making tasks equally distributed across processing cores from the perspective of OS designers and application programmers respectively, are beneficial to solve the scalability problem. However, as shown in this paper, our analysis on the heap manager indicates that researchers should pay attention to techniques of explicit memory management (i.e., malloc and free) on many cores as well. We have evaluated three popular heap managers including Ptmalloc, Hoard and Jemalloc using multi-threaded programs from the PARSEC benchmark suite on emerging tiled many-core processors. The experimental results exhibit that a well-designed scalable heap manager is important to the program performance and all evaluated heap managers have the chance to reduce the performance for some circumstances.