= Use Hash or Map in POSIX Key =

=  current implementation's problem  =

There are 2 problems in current implementation of POSIX Key(more details are described next section).
#The POSIX key area is not properly extended when the number of threads is increased(dynamically created) if POSIX threads are configured as "unlimited", which is a known bug.
#Extra memory is reserved in keys for each thread or task in current implementation, which can be heavy memory overhead when keys increase.=  several design approaches  =
=  current implementation  =

current implementation allocates an array when key creates, which holds all of the threads' or tasks' key value. The pre-allocated array's size is as big as the number of threads in system. It is a waste of memory that allocates key value slot for thread which would not use POSIX key at all. And other problems of current implementation is as [wiki:Current_implementation's_problem current implementation's problem] describes.