Garbage collection in heterogeneous multiprocessor systems is provided. In some illustrative embodiments, garbage collection operations are distributed across a plurality of the processors in the heterogeneous multiprocessor system. Portions of a global mark queue are assigned to processors of the heterogeneous multiprocessor system along with corresponding chunks of a shared memory. The processors perform garbage collection on their assigned portions of the global mark queue and corresponding chunk of shared memory marking memory object references as reachable or adding memory object references to a non-local mark stack. The marked memory objects are merged with a global mark stack and memory object references in the non-local mark stack are merged with a "to be traced" portion of the global mark queue for re-checking using a garbage collection operation.