It is possible to ``close()`` a socket from a different thread to the one that created it. The ``close()`` call will block until any function calls currently using that socket from other tasks have returned.
+It is, however, not possible to delete a task while it is actively waiting on ``select()`` or ``poll()`` APIs. It is always necessary that these APIs exit before destroying the task, as this might corrupt internal structures and cause subsequent crashes of the lwIP.
+(These APIs allocate globally referenced callback pointers on stack, so that when the task gets destroyed before unrolling the stack, the lwIP would still hold pointers to the deleted stack)
David Cermak