Automatic storage management such as garbage collection is essential to list processing systems. Unfortunately, many reclamation algorithms cause long pauses of execution. The pause time is getting shorter in modern garbage collection algorithms, however can not be eliminated perfectly. Parallel garbage collection is one of the efficient garbage collection scheme. It provides high performance list processing and is a key approach to the real time system. No practical parallel garbage collections have been implemented yet. Real time garbage collection can be considered in the same category of parallel garbage collection. There are two disadvantages common to parallel garbage collection and real time garbage collection. One is that collection efficiency becomes 1/2 compared with traditional sequential garbage collection, and the other is List processor's overhead when programs that do not consume many cells. We present solutions for these disadvantages, Partial Marking GC and Conditional...