There are portions of execution of threads during which they vow not to
allocate in the heap or to create handles. These are specific small
portions of code that are understood to not invoke GC or safepoints
on their own so the thread can operate at full speed, and as such are
marked by a NoHandleMark() or NoSafepointVerifier() scope.
It appears as though the GC-a-lot feature may occasionally run
afoul of these blocks, so the interaction of these two should
be investigated and cleaned up.

See comments section for more data.