ares_library_cleanup - c-ares library deinitialization
cc file.c -lcares
The ares_library_cleanup function uninitializes the c-ares library,
freeing all resources previously acquired by ares_library_init(3) when
the library was initialized.
This function must be called when the program using c-ares will no
longer need any c-ares function. Once the program has called
ares_library_cleanup(3) it shall not make any further call to any c-
This function does not cancel any pending c-ares lookups or requests
previously done. Program must use ares_cancel(3) for this purpose.
This function is not thread safe. You have to call it once the program
is about to terminate, but this call must be done once the program has
terminated every single thread that it could have initiated. This is
required to avoid potential race conditions in library
deinitialization, and also due to the fact that ares_library_cleanup(3)
might call functions from other libraries that are thread unsafe, and
could conflict with any other thread that is already using these other
Win32/64 application DLLs shall not call ares_library_cleanup(3) from
the DllMain function. Doing so will produce deadlocks and other
This function was first introduced in c-ares version 1.7.0 along with
the definition of preprocessor symbol CARES_HAVE_ARES_LIBRARY_CLEANUP
as an indication of the availability of this function.
Since the introduction of this function, it is absolutely mandatory to
call it for any Win32/64 program using c-ares.
Non-Win32/64 systems can still use c-ares version 1.7.0 without calling
ares_library_cleanup(3) due to the fact that currently it is nearly a
do-nothing function on non-Win32/64 platforms.
Copyright 1998 by the Massachusetts Institute of Technology.
Copyright (C) 2004-2009 by Daniel Stenberg.
19 May 2009