PEP 11 calls for removing support for the following systems in 3.3:

    Name:             Systems using Mach C Threads
    Unsupported in:   Python 3.2
    Code removed in:  Python 3.3

    Name:             SunOS lightweight processes (LWP)
    Unsupported in:   Python 3.2
    Code removed in:  Python 3.3

    Name:             Systems using --with-pth (GNU pth threads)
    Unsupported in:   Python 3.2
    Code removed in:  Python 3.3

    Name:             Systems using Irix threads
    Unsupported in:   Python 3.2
    Code removed in:  Python 3.3

    Name:             OSF* systems (issue 8606)
    Unsupported in:   Python 3.2 
    Code removed in:  Python 3.3

I think I toke care of OSF cleanup already.

Issue #11876 has been marked as a duplicate of this issue.

Patch removing cpthread, pth, lwp and solaris thread implementations. The patch on configure.in, around the following diff, is invalid:
----
     AC_DEFINE(_REENTRANT)
-    AC_CHECK_HEADER(cthreads.h, [AC_DEFINE(WITH_THREAD)
-    AC_DEFINE(C_THREADS)
-    AC_DEFINE(HURD_C_THREADS, 1,
-    [Define if you are using Mach cthreads directly under /include])
-    LIBS="$LIBS -lthreads"
-    THREADOBJ="Python/thread.o"],[
-    AC_CHECK_HEADER(mach/cthreads.h, [AC_DEFINE(WITH_THREAD)
-    AC_DEFINE(C_THREADS)
-    AC_DEFINE(MACH_C_THREADS, 1,
-    [Define if you are using Mach cthreads under mach /])
-    THREADOBJ="Python/thread.o"],[
     # Just looking for pthread_create in libpthread is not enough:
     # on HP/UX, pthread.h renames pthread_create to a different symbol name.
     # So we really have to include pthread.h, and then link.
----

autoconf will have to be run to update configure.

I am not sure that the patch removes all code related to these threads.

FYI Hurd only supports cthread, without cthread support, Python will not support threads on Hurd anymore.

There are two Hurd issues to move from cthread to pthread
http://savannah.gnu.org/task/?5487 (opened 5 years ago)
http://savannah.gnu.org/task/?7895 (opened 3 years ago)

Python/thread.c contains a reference to a missing file:

#ifdef PLAN9_THREADS
#include "thread_plan9.h"
#endif

But I don't see where PLAN9_THREADS is defined.

remove_threads.patch removes these 3 lines.

--

There is also an unused file: Python/thread_wince.c. Can it be removed?

> Python/thread.c contains a reference to a missing file:
> 
> #ifdef PLAN9_THREADS
> #include "thread_plan9.h"
> #endif
> 
> But I don't see where PLAN9_THREADS is defined.
> 
> remove_threads.patch removes these 3 lines.
> 
> --
> 
> There is also an unused file: Python/thread_wince.c. Can it be removed?

+1 to both.

New changeset 638039a4fef3 by Antoine Pitrou in branch 'default':
Issue #11863: remove unused file Python/thread_wince.h
http://hg.python.org/cpython/rev/638039a4fef3

New changeset 0aa3f90f0830 by Antoine Pitrou in branch 'default':
Issue #11863: Remove support for legacy systems deprecated in Python 3.2
http://hg.python.org/cpython/rev/0aa3f90f0830