Garbage collection consumes significant overhead to reclaim memory used by dead (i.e., unreachable) objects in applications. This paper explores techniques for compiler assisted object reclamation and allocation on an actual JVM. Thereinto, the just-in-time compiler identifies dead objects using pointer and escape analysis combining liveness information and inserts calls to free them. The garbage collector provides runtime support for explicit reclamation and space reuse. Our approach differs from other compiler assisted GC in two crucial ways. First, it identifies not only the objects that are no longer referenced directly by the program, but also the objects that are referenced only by those identified to-be-freed objects. Second, it modifies a parallel garbage collector, and not only frees the identified dead objects, but also tries to reuse their space immediately. The experimental results show that the JIT-assisted GC improves the memory utility and the performance efficiently.