Abstract

One of the biggest disadvantages of nonmoving collectors compared to moving collectors has been their limited ability to deal with memory fragmentation. In this paper, we describe two techniques to reduce fragmentation without the need for moving live data. The first technique reduces internal fragmentation in BiBoP (Big-Bag-of-Pages) like allocators. The second technique reduces external fragmentation using virtual memory calls available in most modern operating systems. It can also reduce the size of the heap after periods of great activity in long lived applications. These techniques have been successfully used in Geodesic Systems ’ Great Circle, a commercially-available conservative garbage collector. This paper describes these techniques, their implementation, and some experimental results. 1.1 Keywords Memory allocation, garbage collection, fragmentation, conservative garbage collection, non-copying garbage collection 2.

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