[perl #130649] Threads, shared memory, blessed objects fail to call->DESTROY method

The bug is that the destructor of an embedded shared object will not be called after the enclosing shared object is destroyed:

1.  Create shared objects $xx and $yy.
2.  Embed $yy inside $XX:   $xx->{embedded} = $yy
3.  Undef $yy.  Its destructor is not called because it's still referenced by $xx.  (This is as expected.)
4.  Undef $xx.  The destructor for $xx is called (as expected), but the destructor for $yy is not (bug).

If the above is done with ordinary objects, the the destructors for both $xx and $yy will be called, as expected.

One workaround is to code the destructor to actively dereference any embedded objects.

The attached code illustrates both the bug and the workaround.

• [perl #130649] Threads, shared memory, blessed objects fail to call->DESTROY method by Jerry D. Hedden via RT