Thread-Specific Heaps
Bjarne Steensgaard, Microsoft Research

In typical multi-threaded programs, many objects never escape the thread that
created them.  We propose allocating such objects in thread-specific heaps.
A key property of such thread-specific heaps is absence of pointers into the
heap from objects in other heaps.  Objects that cannot be allocated in
thread-specific heaps may be allocated in a shared heap.

We make a number of observations about thread-specific heaps:

1. Thread-specific heaps can be garbage-collected independent of other
   thread-specific heaps, and in particular can be garbage-collected
   concurrently with such heaps.

2. Having thread-specific heaps without cross-pointers is likely to increase
   locality during garbage collection.

3. Having smaller heaps that can be garbage-collected independently may
   decrease maximum memory usage for semi-space copying garbage collectors.

We report on our experience with thread-specific heaps in Marmot, an
ahead-of-time Java-to-native code compiler.