Issue #9284 (closed) relates to forkProcess, which previously invoked the same code that is invoked by hs_exit and uncovered this problem. The resolution of #9284 (closed) is to not invoke the equivalent of hs_exit (for reasons that you can see in #9284 (closed)). However, hs_exit can be called by programs that explicitly create and teardown a Haskell runtime, so the problem displayed by #9284 (closed) can still occur for those programs.

The problem has only been observed on OS X, though it probably could occur on Linux OSes as well.