[SCM] POSIX threading library branch, master, updated. d8569a7a43651ca1c1149540619254e224ed7c9e

[Richard Braun]

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- Log -----------------------------------------------------------------
commit d8569a7a43651ca1c1149540619254e224ed7c9e
Author: Richard Braun <address@hidden>
Date:   Thu Dec 26 21:19:58 2013 +0100

    Implement thread destruction
    
    This change makes libpthread release almost every resource allocated for
    a thread, including the kernel thread, its send right, its reply port
    and its stack. This improves resource usage after peaks of activity
    during which servers can create hundreds or even thousands of threads.
    
    To achieve this, the library relies on the recently added
    thread_terminate_release one-way GNU Mach RPC, which allows threads to
    release their last resources along with terminating in a single
    operation. The pthread_exit function unconditionally releases all the
    resources it can, including other kernel objects (namely the port used
    for blocking and waking up) and signal states. When releasing the
    pthread structure, a reference counter is used so that joinable threads
    remain available. Once the reference counter drops to 0, the pthread
    structure can be recycled. Thread local storage (TLS) is also recycled
    since it needs to remain allocated while terminating the thread, as it
    is there that the reply port is stored. TLS could be released too, after
    grabbing the reply port name, but it is difficult to make sure no RPC
    involving a reply port is used afterwards, so the simpler solution of
    recycling TLS was chosen.
    
    * Makefile (libpthread-routines): Replace pt-thread-halt with
    pt-thread-terminate.
    * pthread/pt-alloc.c (initialize_pthread): Set reference counter and
    unconditionally initialize new threads completely.
    (__pthread_alloc): Remove call to __pthread_thread_halt, update calls
    to initialize_pthread.
    * pthread/pt-create.c (__pthread_create_internal): Don't attempt to
    reuse stacks, handle reference counter, update failure handling.
    * pthread/pt-dealloc.c: Include bits/pt-atomic.h.
    (__pthread_dealloc): Make pthread structure available for reuse when
    reference counter reaches 0.
    * pthread/pt-detach.c (pthread_detach): Assume the target thread takes
    care of its own resources and, as a result, simply unreference its
    pthread struct.
    * pthread/pt-exit.c (__pthread_exit): Release resources and terminate.
    * pthread/pt-internal.h (struct __pthread): New `nr_refs' member.
    (__pthread_alloc): Update description.
    (__pthread_dealloc): Likewise.
    (__pthread_thread_dealloc): Likewise.
    (__pthread_thread_terminate): New declaration.
    * pthread/pt-join.c (pthread_join): Assume the target thread takes care
    of its own resources and, as a result, simply unreference its pthread
    struct.
    * sysdeps/mach/hurd/pt-sigstate-destroy.c
    (__pthread_sigstate_destroy): Call _hurd_sigstate_delete.
    * sysdeps/mach/hurd/pt-sigstate-init.c (__pthread_sigstate_init): Call
    _hurd_thread_sigstate and _hurd_sigstate_set_global_rcv when
    appropriate.
    * sysdeps/mach/hurd/pt-sysdep.c (__pthread_create_internal): Prevent
    the library from releasing the stack of the main thread.
    * sysdeps/mach/hurd/pt-sysdep.h (PTHREAD_SYSDEP_MEMBERS): Remove
    `have_kernel_resources' from the list of sysdep members.
    * sysdeps/mach/pt-thread-alloc.c (__pthread_thread_alloc): Update
    thread allocation.
    * sysdeps/mach/pt-thread-dealloc.c (__pthread_thread_dealloc): Update
    description.
    * sysdeps/mach/pt-thread-halt.c: Remove file.
    * sysdeps/mach/pt-thread-start.c (__pthread_thread_start): Fix the
    conditions under which a thread should actually be started.
    * sysdeps/mach/pt-thread-terminate.c: New file.

-----------------------------------------------------------------------

Summary of changes:
 Makefile                                |    2 +-
 pthread/pt-alloc.c                      |   22 ++--------
 pthread/pt-create.c                     |   69 ++++++++++++++----------------
 pthread/pt-dealloc.c                    |    5 ++
 pthread/pt-detach.c                     |   24 ++--------
 pthread/pt-exit.c                       |   35 +++++++--------
 pthread/pt-internal.h                   |   36 +++++++++------
 pthread/pt-join.c                       |   18 +-------
 sysdeps/mach/hurd/pt-sigstate-destroy.c |    2 +-
 sysdeps/mach/hurd/pt-sigstate-init.c    |   18 +++++++-
 sysdeps/mach/hurd/pt-sysdep.c           |    5 ++
 sysdeps/mach/hurd/pt-sysdep.h           |    3 +-
 sysdeps/mach/pt-thread-alloc.c          |   31 +++----------
 sysdeps/mach/pt-thread-dealloc.c        |    3 +-
 sysdeps/mach/pt-thread-halt.c           |   37 ----------------
 sysdeps/mach/pt-thread-start.c          |    4 +-
 sysdeps/mach/pt-thread-terminate.c      |   72 +++++++++++++++++++++++++++++++
 17 files changed, 194 insertions(+), 192 deletions(-)
 delete mode 100644 sysdeps/mach/pt-thread-halt.c
 create mode 100644 sysdeps/mach/pt-thread-terminate.c


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