conservative garbage collector for C and C++

 Boehm-Demers-Weiser's GC is a garbage collecting storage allocator that is
 intended to be used as a plug-in replacement for C's malloc or C++'s new().
 .
 It allows you to allocate memory basically as you normally would without
 explicitly deallocating memory that is no longer useful. The collector
 automatically recycles memory when it determines that it can no longer be
 used.
 .
 This version of the collector is thread safe, has C++ support and uses the
 defaults for everything else. However, it does not work as a drop-in malloc(3)
 replacement.