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0.9.2.38: thread cleanup, paranoid

Browse source 
* fixed 32bitness in some places
  * untangled waitqueues, mutexes and spinlocks
  * updated the user manual
  * removed target-unithread.lisp and target-multithread.lisp and
    put everything into target-thread.lisp mainly for OOAO the docstrings,
    but also to provide as much as possible of the thread interface
    in unithread builds
This commit is contained in:
Gabor Melis 2005-07-11 15:31:07 +00:00
parent bb756e3d4b
commit ad3beba970
11 changed files with 618 additions and 523 deletions
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1
INSTALL
View file

@ -228,6 +228,7 @@ INSTALLING SBCL
CMUCL
OpenMCL
CLISP (recent versions only)
ABCL (recent versions only)
Note that every release isn't tested with every possible host
compiler. You're most likely to get a clean build with SBCL itself

4
build-order.lisp-expr
View file

@ -639,10 +639,6 @@
("src/code/alloc" :not-host)
("src/code/target-thread" :not-host)
#!+sb-thread
("src/code/target-multithread" :not-host)
#!-sb-thread
("src/code/target-unithread" :not-host)
;; defines SB!DI:DO-DEBUG-FUN-BLOCKS, needed by target-disassem.lisp
("src/code/gc" :not-host)
("src/code/purify" :not-host)

72
doc/manual/threading.texinfo
View file

@ -9,9 +9,11 @@ multiprocessing on machines that have more than one CPU, but it does
not allow Lisp control of the scheduler. This is found in the
SB-THREAD package.
This requires x86 and Linux kernel 2.6 or systems with NPTL backports.
This requires x86/x86-64 and Linux kernel 2.6 or systems with NPTL
backports.
@menu
* Threading basics::
* Special Variables::
* Mutex Support::
* Waitqueue/condition variables::
@ -19,6 +21,25 @@ This requires x86 and Linux kernel 2.6 or systems with NPTL backports.
* Implementation (Linux x86)::
@end menu
@node Threading basics
@comment node-name, next, previous, up
@section Threading basics
@lisp
(make-thread (lambda () (write-line "Hello, world")))
@end lisp
@include struct-sb-thread-thread.texinfo
@include var-sb-thread-star-current-thread-star.texinfo
@include fun-sb-thread-make-thread.texinfo
@include fun-sb-thread-thread-alive-p.texinfo
@include fun-sb-thread-list-all-threads.texinfo
@include condition-sb-thread-interrupt-thread-error.texinfo
@include fun-sb-thread-interrupt-thread-error-thread.texinfo
@include fun-sb-thread-interrupt-thread-error-errno.texinfo
@include fun-sb-thread-interrupt-thread.texinfo
@include fun-sb-thread-terminate-thread.texinfo
@node Special Variables
@comment node-name, next, previous, up
@section Special Variables
@ -37,6 +58,16 @@ bindings (e.g. using LET) are local to the thread;
initial values in a new thread are taken from the thread that created it.
@end itemize
The last point means that
@lisp
(defparameter *x* 0)
(let ((*x* 1))
(sb-thread:make-thread (lambda () (print *x*))))
@end lisp
prints @code{1}.
@node Mutex Support
@comment node-name, next, previous, up
@section Mutex Support
@ -66,9 +97,17 @@ if you want a bounded wait.
(make-thread #'thread-fn)
(make-thread #'thread-fn)
@end lisp
@include struct-sb-thread-mutex.texinfo
@include fun-sb-thread-make-mutex.texinfo
@include fun-sb-thread-mutex-name.texinfo
@include fun-sb-thread-mutex-value.texinfo
@include fun-sb-thread-get-mutex.texinfo
@include fun-sb-thread-release-mutex.texinfo
@include macro-sb-thread-with-mutex.texinfo
@include macro-sb-thread-with-recursive-lock.texinfo
@node Waitqueue/condition variables
@comment node-name, next, previous, up
@section Waitqueue/condition variables
@ -144,9 +183,15 @@ it.
(make-thread #'writer)
(make-thread #'reader)
(make-thread #'reader)
@end lisp
@include struct-sb-thread-waitqueue.texinfo
@include fun-sb-thread-make-waitqueue.texinfo
@include fun-sb-thread-waitqueue-name.texinfo
@include fun-sb-thread-condition-wait.texinfo
@include fun-sb-thread-condition-notify.texinfo
@include fun-sb-thread-condition-broadcast.texinfo
@node Sessions/Debugging
@comment node-name, next, previous, up
@section Sessions/Debugging
@ -177,20 +222,17 @@ leaves other sessions running.
@node Implementation (Linux x86)
@comment node-name, next, previous, up
@section Implementation (Linux x86)
@section Implementation (Linux x86/x86-64)
On Linux x86, threading is implemented using @code{clone()} and does
not involve pthreads. This is not because there is anything wrong
with pthreads @emph{per se}, but there is plenty wrong (from our
perspective) with LinuxThreads. SBCL threads are mapped 1:1 onto
Linux tasks which share a VM but nothing else - each has its own
process id and can be seen in e.g. @command{ps} output.
Threading is implemented using pthreads and some Linux specific bits
like futexes.
Per-thread local bindings for special variables is achieved using the
%fs segment register to point to a per-thread storage area. This may
cause interesting results if you link to foreign code that expects
threading or creates new threads, and the thread library in question
uses %fs in an incompatible way.
On x86 the per-thread local bindings for special variables is achieved
using the %fs segment register to point to a per-thread storage area.
This may cause interesting results if you link to foreign code that
expects threading or creates new threads, and the thread library in
question uses %fs in an incompatible way. On x86-64 the r12 register
has a similar role.
Queues require the @code{sys_futex()} system call to be available:
this is the reason for the NPTL requirement. We test at runtime that

17
package-data-list.lisp-expr
View file

@ -1587,15 +1587,20 @@ is a good idea, but see SB-SYS re. blurring of boundaries."
:name "SB!THREAD"
:use ("CL" "SB!ALIEN" "SB!INT")
:doc "public (but low-level): native thread support"
:export ("*CURRENT-THREAD*" "MAKE-THREAD" "THREAD"
:export ("*CURRENT-THREAD*" "THREAD" "MAKE-THREAD"
"THREAD-NAME" "THREAD-ALIVE-P"
"LIST-ALL-THREADS"
"MAKE-LISTENER-THREAD" "DESTROY-THREAD" "TERMINATE-THREAD"
"INTERRUPT-THREAD" "WITH-RECURSIVE-LOCK"
"MUTEX" "MAKE-MUTEX" "GET-MUTEX" "RELEASE-MUTEX" "WITH-MUTEX"
"MUTEX-VALUE" "WAITQUEUE" "MAKE-WAITQUEUE"
"INTERRUPT-THREAD-ERROR"
"INTERRUPT-THREAD-ERROR-THREAD"
"INTERRUPT-THREAD-ERROR-ERRNO"
"INTERRUPT-THREAD" "TERMINATE-THREAD" "DESTROY-THREAD"
"MUTEX" "MAKE-MUTEX" "MUTEX-NAME" "MUTEX-VALUE"
"GET-MUTEX" "RELEASE-MUTEX" "WITH-MUTEX"
"WITH-RECURSIVE-LOCK"
"WAITQUEUE" "MAKE-WAITQUEUE" "WAITQUEUE-NAME"
"CONDITION-WAIT" "CONDITION-NOTIFY" "CONDITION-BROADCAST"
"WITH-RECURSIVE-LOCK" "RELEASE-FOREGROUND" "WITH-NEW-SESSION"))
"MAKE-LISTENER-THREAD"
"RELEASE-FOREGROUND" "WITH-NEW-SESSION"))
#s(sb-cold:package-data
:name "SB!LOOP"

396
src/code/target-multithread.lisp
View file

@ -1,396 +0,0 @@
;;;; support for threads in the target machine
;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.
(in-package "SB!THREAD")
(define-alien-routine ("create_thread" %create-thread)
system-area-pointer
(lisp-fun-address unsigned-long))
(define-alien-routine reap-dead-thread void
(thread-sap system-area-pointer))
;;;; queues, locks
;; spinlocks use 0 as "free" value: higher-level locks use NIL
(declaim (inline get-spinlock release-spinlock))
(defun get-spinlock (lock offset new-value)
(declare (optimize (speed 3) (safety 0)))
;; %instance-set-conditional can test for 0 (which is a fixnum) and
;; store any value
(loop until
(eql (sb!vm::%instance-set-conditional lock offset 0 new-value) 0)))
(defun release-spinlock (lock offset)
(declare (optimize (speed 3) (safety 0)))
;; %instance-set-conditional cannot compare arbitrary objects
;; meaningfully, so
;; (sb!vm::%instance-set-conditional lock offset our-value 0)
;; does not work for bignum thread ids.
(sb!vm::%instance-set lock offset 0))
(defmacro with-spinlock ((queue) &body body)
`(unwind-protect
(progn
(get-spinlock ,queue 2 *current-thread*)
,@body)
(release-spinlock ,queue 2)))
;;;; the higher-level locking operations are based on waitqueues
(declaim (inline waitqueue-data-address mutex-value-address))
(defstruct waitqueue
(name nil :type (or null simple-string))
(lock 0)
(data nil))
;;; The bare 4 here and 5 below are offsets of the slots in the struct.
;;; There ought to be some better way to get these numbers
(defun waitqueue-data-address (lock)
(declare (optimize (speed 3)))
(sb!ext:truly-the
(unsigned-byte 32)
(+ (sb!kernel:get-lisp-obj-address lock)
(- (* 4 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
(defstruct (mutex (:include waitqueue))
(value nil))
(defun mutex-value-address (lock)
(declare (optimize (speed 3)))
(sb!ext:truly-the
(unsigned-byte 32)
(+ (sb!kernel:get-lisp-obj-address lock)
(- (* 5 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
(declaim (inline futex-wait futex-wake))
(sb!alien:define-alien-routine
"futex_wait" int (word unsigned-long) (old-value unsigned-long))
(sb!alien:define-alien-routine
"futex_wake" int (word unsigned-long) (n unsigned-long))
;;;; mutex
(defun get-mutex (lock &optional new-value (wait-p t))
"Acquire LOCK, setting it to NEW-VALUE or some suitable default value
if NIL. If WAIT-P is non-NIL and the lock is in use, sleep until it
is available"
(declare (type mutex lock) (optimize (speed 3)))
(let (old)
(unless new-value (setf new-value *current-thread*))
(when (eql new-value (mutex-value lock))
(warn "recursive lock attempt ~S~%" lock)
(format *debug-io* "Thread: ~A~%" *current-thread*)
(sb!debug:backtrace most-positive-fixnum *debug-io*)
(force-output *debug-io*))
(loop
(unless
(setf old (sb!vm::%instance-set-conditional lock 4 nil new-value))
(return t))
(unless wait-p (return nil))
(futex-wait (mutex-value-address lock)
(sb!kernel:get-lisp-obj-address old)))))
(defun release-mutex (lock)
(declare (type mutex lock))
(setf (mutex-value lock) nil)
(futex-wake (mutex-value-address lock) 1))
;;;; condition variables
(defun condition-wait (queue lock)
"Atomically release LOCK and enqueue ourselves on QUEUE. Another
thread may subsequently notify us using CONDITION-NOTIFY, at which
time we reacquire LOCK and return to the caller."
(assert lock)
(let ((value (mutex-value lock)))
(unwind-protect
(let ((me *current-thread*))
;; XXX we should do something to ensure that the result of this setf
;; is visible to all CPUs
(setf (waitqueue-data queue) me)
(release-mutex lock)
;; Now we go to sleep using futex-wait. If anyone else
;; manages to grab LOCK and call CONDITION-NOTIFY during
;; this comment, it will change queue->data, and so
;; futex-wait returns immediately instead of sleeping.
;; Ergo, no lost wakeup
(futex-wait (waitqueue-data-address queue)
(sb!kernel:get-lisp-obj-address me)))
;; If we are interrupted while waiting, we should do these things
;; before returning. Ideally, in the case of an unhandled signal,
;; we should do them before entering the debugger, but this is
;; better than nothing.
(get-mutex lock value))))
(defun condition-notify (queue)
"Notify one of the processes waiting on QUEUE"
(let ((me *current-thread*))
;; no problem if >1 thread notifies during the comment in
;; condition-wait: as long as the value in queue-data isn't the
;; waiting thread's id, it matters not what it is
;; XXX we should do something to ensure that the result of this setf
;; is visible to all CPUs
(setf (waitqueue-data queue) me)
(futex-wake (waitqueue-data-address queue) 1)))
(defun condition-broadcast (queue)
(let ((me *current-thread*))
(setf (waitqueue-data queue) me)
(futex-wake (waitqueue-data-address queue) (ash 1 30))))
;;;; job control, independent listeners
(defstruct session
(lock (make-mutex :name "session lock"))
(threads nil)
(interactive-threads nil)
(interactive-threads-queue (make-waitqueue)))
(defvar *session* nil)
;;; the debugger itself tries to acquire the session lock, don't let
;;; funny situations (like getting a sigint while holding the session
;;; lock) occur
(defmacro with-session-lock ((session) &body body)
`(sb!sys:without-interrupts
(with-mutex ((session-lock ,session))
,@body)))
(defun new-session ()
(make-session :threads (list *current-thread*)
:interactive-threads (list *current-thread*)))
(defun init-job-control ()
(setf *session* (new-session)))
(defun %delete-thread-from-session (thread session)
(with-session-lock (session)
(setf (session-threads session)
(delete thread (session-threads session))
(session-interactive-threads session)
(delete thread (session-interactive-threads session)))))
(defun call-with-new-session (fn)
(%delete-thread-from-session *current-thread* *session*)
(let ((*session* (new-session)))
(funcall fn)))
(defmacro with-new-session (args &body forms)
(declare (ignore args)) ;for extensibility
(sb!int:with-unique-names (fb-name)
`(labels ((,fb-name () ,@forms))
(call-with-new-session (function ,fb-name)))))
;;; Remove thread from its session, if it has one.
(defun handle-thread-exit (thread)
(with-mutex (*all-threads-lock*)
(setq *all-threads* (delete thread *all-threads*)))
(when *session*
(%delete-thread-from-session thread *session*)))
(defun terminate-session ()
"Kill all threads in session except for this one. Does nothing if current
thread is not the foreground thread"
;; FIXME: threads created in other threads may escape termination
(let ((to-kill
(with-session-lock (*session*)
(and (eq *current-thread*
(car (session-interactive-threads *session*)))
(session-threads *session*)))))
;; do the kill after dropping the mutex; unwind forms in dying
;; threads may want to do session things
(dolist (thread to-kill)
(unless (eq thread *current-thread*)
;; terminate the thread but don't be surprised if it has
;; exited in the meantime
(handler-case (terminate-thread thread)
(interrupt-thread-error ()))))))
;;; called from top of invoke-debugger
(defun debugger-wait-until-foreground-thread (stream)
"Returns T if thread had been running in background, NIL if it was
interactive."
(declare (ignore stream))
(prog1
(with-session-lock (*session*)
(not (member *current-thread*
(session-interactive-threads *session*))))
(get-foreground)))
(defun get-foreground ()
(let ((was-foreground t))
(loop
(with-session-lock (*session*)
(let ((int-t (session-interactive-threads *session*)))
(when (eq (car int-t) *current-thread*)
(unless was-foreground
(format *query-io* "Resuming thread ~A~%" *current-thread*))
(return-from get-foreground t))
(setf was-foreground nil)
(unless (member *current-thread* int-t)
(setf (cdr (last int-t))
(list *current-thread*)))
(condition-wait
(session-interactive-threads-queue *session*)
(session-lock *session*)))))))
(defun release-foreground (&optional next)
"Background this thread. If NEXT is supplied, arrange for it to
have the foreground next"
(with-session-lock (*session*)
(setf (session-interactive-threads *session*)
(delete *current-thread* (session-interactive-threads *session*)))
(when next
(setf (session-interactive-threads *session*)
(list* next
(delete next (session-interactive-threads *session*)))))
(condition-broadcast (session-interactive-threads-queue *session*))))
(defun foreground-thread ()
(car (session-interactive-threads *session*)))
(defun make-listener-thread (tty-name)
(assert (probe-file tty-name))
(let* ((in (sb!unix:unix-open (namestring tty-name) sb!unix:o_rdwr #o666))
(out (sb!unix:unix-dup in))
(err (sb!unix:unix-dup in)))
(labels ((thread-repl ()
(sb!unix::unix-setsid)
(let* ((sb!impl::*stdin*
(sb!sys:make-fd-stream in :input t :buffering :line
:dual-channel-p t))
(sb!impl::*stdout*
(sb!sys:make-fd-stream out :output t :buffering :line
:dual-channel-p t))
(sb!impl::*stderr*
(sb!sys:make-fd-stream err :output t :buffering :line
:dual-channel-p t))
(sb!impl::*tty*
(sb!sys:make-fd-stream err :input t :output t
:buffering :line
:dual-channel-p t))
(sb!impl::*descriptor-handlers* nil))
(with-new-session ()
(unwind-protect
(sb!impl::toplevel-repl nil)
(sb!int:flush-standard-output-streams))))))
(make-thread #'thread-repl))))
;;;; the beef
(defun make-thread (function &key name)
(let* ((thread (%make-thread :name name))
(setup-p nil)
(real-function (coerce function 'function))
(thread-sap
(%create-thread
(sb!kernel:get-lisp-obj-address
(lambda ()
;; FIXME: use semaphores?
(loop until setup-p)
;; in time we'll move some of the binding presently done in C
;; here too
(let ((*current-thread* thread)
(sb!kernel::*restart-clusters* nil)
(sb!kernel::*handler-clusters* nil)
(sb!kernel::*condition-restarts* nil)
(sb!impl::*descriptor-handlers* nil) ; serve-event
(sb!impl::*available-buffers* nil)) ;for fd-stream
;; can't use handling-end-of-the-world, because that flushes
;; output streams, and we don't necessarily have any (or we
;; could be sharing them)
(unwind-protect
(catch 'sb!impl::toplevel-catcher
(catch 'sb!impl::%end-of-the-world
(with-simple-restart
(terminate-thread
(format nil "~~@<Terminate this thread (~A)~~@:>"
*current-thread*))
;; now that most things have a chance to work
;; properly without messing up other threads, it's
;; time to enable signals
(sb!unix::reset-signal-mask)
(unwind-protect
(funcall real-function)
;; we're going down, can't handle
;; interrupts sanely anymore
(sb!unix::block-blockable-signals)))))
;; mark the thread dead, so that the gc does not
;; wait for it to handle sig-stop-for-gc
(%set-thread-state thread :dead)
;; and remove what can be the last reference to
;; the thread object
(handle-thread-exit thread)
0))
(values))))))
(when (sb!sys:sap= thread-sap (sb!sys:int-sap 0))
(error "Can't create a new thread"))
(setf (thread-%sap thread) thread-sap)
(with-mutex (*all-threads-lock*)
(push thread *all-threads*))
(with-session-lock (*session*)
(push thread (session-threads *session*)))
(setq setup-p t)
(sb!impl::finalize thread (lambda () (reap-dead-thread thread-sap)))
thread))
(defun destroy-thread (thread)
"Deprecated. Soon to be removed or reimplemented using pthread_cancel."
(terminate-thread thread))
;;; a moderate degree of care is expected for use of interrupt-thread,
;;; due to its nature: if you interrupt a thread that was holding
;;; important locks then do something that turns out to need those
;;; locks, you probably won't like the effect.
(define-condition interrupt-thread-error (error)
((thread :reader interrupt-thread-error-thread :initarg :thread)
(errno :reader interrupt-thread-error-errno :initarg :errno))
(:report (lambda (c s)
(format s "interrupt thread ~A failed (~A: ~A)"
(interrupt-thread-error-thread c)
(interrupt-thread-error-errno c)
(strerror (interrupt-thread-error-errno c))))))
(defun interrupt-thread (thread function)
"Interrupt THREAD and make it run FUNCTION."
(let ((function (coerce function 'function)))
(multiple-value-bind (res err)
(sb!unix::syscall ("interrupt_thread"
system-area-pointer sb!alien:unsigned-long)
thread
(thread-%sap thread)
(sb!kernel:get-lisp-obj-address function))
(unless res
(error 'interrupt-thread-error :thread thread :errno err)))))
(defun terminate-thread (thread)
"Terminate the thread identified by THREAD, by causing it to run
SB-EXT:QUIT - the usual cleanup forms will be evaluated"
(interrupt-thread thread 'sb!ext:quit))
;;; internal use only. If you think you need to use this, either you
;;; are an SBCL developer, are doing something that you should discuss
;;; with an SBCL developer first, or are doing something that you
;;; should probably discuss with a professional psychiatrist first
(defun symbol-value-in-thread (symbol thread)
(let ((thread-sap (thread-%sap thread)))
(let* ((index (sb!vm::symbol-tls-index symbol))
(tl-val (sb!sys:sap-ref-word thread-sap
(* sb!vm:n-word-bytes index))))
(if (eql tl-val sb!vm::unbound-marker-widetag)
(sb!vm::symbol-global-value symbol)
(sb!kernel:make-lisp-obj tl-val)))))

514
src/code/target-thread.lisp
View file

@ -1,5 +1,4 @@
;;;; support for threads in the target machine common to uni- and
;;;; multithread systems
;;;; support for threads in the target machine
;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
@ -12,10 +11,23 @@
(in-package "SB!THREAD")
;;; set the doc here because in early-thread FDOCUMENTATION is not
;;; available, yet
#!+sb-doc
(setf (sb!kernel:fdocumentation '*current-thread* 'variable)
"Bound in each thread to the thread itself.")
(defstruct (thread (:constructor %make-thread))
#!+sb-doc
"Thread type. Do not rely on threads being structs as it may change
in future versions."
name
%sap)
#!+sb-doc
(setf (sb!kernel:fdocumentation 'thread-name 'function)
"The name of the thread. Setfable.")
(def!method print-object ((thread thread) stream)
(if (thread-name thread)
(print-unreadable-object (thread stream :type t :identity t)
@ -50,6 +62,8 @@
(:dead #.(sb!vm:fixnumize 3))))))
(defun thread-alive-p (thread)
#!+sb-doc
"Check if THREAD is running."
(not (eq :dead (thread-state thread))))
;; A thread is eligible for gc iff it has finished and there are no
@ -59,6 +73,8 @@
(defvar *all-threads-lock* (make-mutex :name "all threads lock"))
(defun list-all-threads ()
#!+sb-doc
"Return a list of the live threads."
(with-mutex (*all-threads-lock*)
(copy-list *all-threads*)))
@ -79,3 +95,497 @@
;; in case we are in reinit since saving core with multiple
;; threads doesn't work.
(setq *all-threads* (list initial-thread))))
;;;;
#!+sb-thread
(progn
(define-alien-routine ("create_thread" %create-thread)
system-area-pointer
(lisp-fun-address unsigned-long))
(define-alien-routine reap-dead-thread void
(thread-sap system-area-pointer))
(declaim (inline futex-wait futex-wake))
(sb!alien:define-alien-routine "futex_wait"
int (word unsigned-long) (old-value unsigned-long))
(sb!alien:define-alien-routine "futex_wake"
int (word unsigned-long) (n unsigned-long)))
;;; used by debug-int.lisp to access interrupt contexts
#!-(and sb-fluid sb-thread) (declaim (inline sb!vm::current-thread-offset-sap))
#!-sb-thread
(defun sb!vm::current-thread-offset-sap (n)
(declare (type (unsigned-byte 27) n))
(sb!sys:sap-ref-sap (alien-sap (extern-alien "all_threads" (* t)))
(* n sb!vm:n-word-bytes)))
;;;; spinlocks
(defstruct spinlock
#!+sb-doc
"Spinlock type."
(name nil :type (or null simple-string))
(value 0))
(declaim (inline get-spinlock release-spinlock))
;;; The bare 2 here and below are offsets of the slots in the struct.
;;; There ought to be some better way to get these numbers
(defun get-spinlock (spinlock new-value)
(declare (optimize (speed 3) (safety 0))
#!-sb-thread
(ignore spinlock new-value))
;; %instance-set-conditional can test for 0 (which is a fixnum) and
;; store any value
#!+sb-thread
(loop until
(eql (sb!vm::%instance-set-conditional spinlock 2 0 new-value) 0)))
(defun release-spinlock (spinlock)
(declare (optimize (speed 3) (safety 0))
#!-sb-thread (ignore spinlock))
;; %instance-set-conditional cannot compare arbitrary objects
;; meaningfully, so
;; (sb!vm::%instance-set-conditional spinlock 2 our-value 0)
;; does not work for bignum thread ids.
#!+sb-thread
(sb!vm::%instance-set spinlock 2 0))
(defmacro with-spinlock ((spinlock) &body body)
(sb!int:with-unique-names (lock)
`(let ((,lock ,spinlock))
(get-spinlock ,lock *current-thread*)
(unwind-protect
(progn ,@body)
(release-spinlock ,lock)))))
;;;; mutexes
(defstruct mutex
#!+sb-doc
"Mutex type."
(name nil :type (or null simple-string))
(value nil))
#!+sb-doc
(setf (sb!kernel:fdocumentation 'make-mutex 'function)
"Create a mutex."
(sb!kernel:fdocumentation 'mutex-name 'function)
"The name of the mutex. Setfable."
(sb!kernel:fdocumentation 'mutex-value 'function)
"The value of the mutex. NIL if the mutex is free. Setfable.")
#!+sb-thread
(declaim (inline mutex-value-address))
#!+sb-thread
(defun mutex-value-address (mutex)
(declare (optimize (speed 3)))
(sb!ext:truly-the
sb!vm:word
(+ (sb!kernel:get-lisp-obj-address mutex)
(- (* 3 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
(defun get-mutex (mutex &optional new-value (wait-p t))
#!+sb-doc
"Acquire MUTEX, setting it to NEW-VALUE or some suitable default
value if NIL. If WAIT-P is non-NIL and the mutex is in use, sleep
until it is available"
(declare (type mutex mutex) (optimize (speed 3)))
(unless new-value (setf new-value *current-thread*))
#!-sb-thread
(let ((old-value (mutex-value mutex)))
(when (and old-value wait-p)
(error "In unithread mode, mutex ~S was requested with WAIT-P ~S and ~
new-value ~S, but has already been acquired (with value ~S)."
mutex wait-p new-value old-value))
(setf (mutex-value mutex) new-value)
t)
#!+sb-thread
(let (old)
(when (eql new-value (mutex-value mutex))
(warn "recursive lock attempt ~S~%" mutex)
(format *debug-io* "Thread: ~A~%" *current-thread*)
(sb!debug:backtrace most-positive-fixnum *debug-io*)
(force-output *debug-io*))
(loop
(unless
(setf old (sb!vm::%instance-set-conditional mutex 2 nil new-value))
(return t))
(unless wait-p (return nil))
(futex-wait (mutex-value-address mutex)
(sb!kernel:get-lisp-obj-address old)))))
(defun release-mutex (mutex)
#!+sb-doc
"Release MUTEX by setting it to NIL. Wake up threads waiting for
this mutex."
(declare (type mutex mutex))
(setf (mutex-value mutex) nil)
#!+sb-thread
(futex-wake (mutex-value-address mutex) 1))
;;;; waitqueues/condition variables
(defstruct (waitqueue (:constructor %make-waitqueue))
#!+sb-doc
"Waitqueue type."
(name nil :type (or null simple-string))
(data nil))
(defun make-waitqueue (&key name)
#!+sb-doc
"Create a waitqueue."
(%make-waitqueue :name name))
#!+sb-doc
(setf (sb!kernel:fdocumentation 'waitqueue-name 'function)
"The name of the waitqueue. Setfable.")
#!+sb-thread
(declaim (inline waitqueue-data-address))
#!+sb-thread
(defun waitqueue-data-address (waitqueue)
(declare (optimize (speed 3)))
(sb!ext:truly-the
sb!vm:word
(+ (sb!kernel:get-lisp-obj-address waitqueue)
(- (* 3 sb!vm:n-word-bytes) sb!vm:instance-pointer-lowtag))))
(defun condition-wait (queue mutex)
#!+sb-doc
"Atomically release MUTEX and enqueue ourselves on QUEUE. Another
thread may subsequently notify us using CONDITION-NOTIFY, at which
time we reacquire MUTEX and return to the caller."
#!-sb-thread (declare (ignore queue))
(assert mutex)
#!-sb-thread (error "Not supported in unithread builds.")
#!+sb-thread
(let ((value (mutex-value mutex)))
(unwind-protect
(let ((me *current-thread*))
;; XXX we should do something to ensure that the result of this setf
;; is visible to all CPUs
(setf (waitqueue-data queue) me)
(release-mutex mutex)
;; Now we go to sleep using futex-wait. If anyone else
;; manages to grab MUTEX and call CONDITION-NOTIFY during
;; this comment, it will change queue->data, and so
;; futex-wait returns immediately instead of sleeping.
;; Ergo, no lost wakeup
(futex-wait (waitqueue-data-address queue)
(sb!kernel:get-lisp-obj-address me)))
;; If we are interrupted while waiting, we should do these things
;; before returning. Ideally, in the case of an unhandled signal,
;; we should do them before entering the debugger, but this is
;; better than nothing.
(get-mutex mutex value))))
(defun condition-notify (queue)
#!+sb-doc
"Notify one of the threads waiting on QUEUE."
#!-sb-thread (declare (ignore queue))
#!-sb-thread (error "Not supported in unithread builds.")
#!+sb-thread
(let ((me *current-thread*))
;; no problem if >1 thread notifies during the comment in
;; condition-wait: as long as the value in queue-data isn't the
;; waiting thread's id, it matters not what it is
;; XXX we should do something to ensure that the result of this setf
;; is visible to all CPUs
(setf (waitqueue-data queue) me)
(futex-wake (waitqueue-data-address queue) 1)))
(defun condition-broadcast (queue)
#!+sb-doc
"Notify all threads waiting on QUEUE."
#!-sb-thread (declare (ignore queue))
#!-sb-thread (error "Not supported in unithread builds.")
#!+sb-thread
(let ((me *current-thread*))
(setf (waitqueue-data queue) me)
(futex-wake (waitqueue-data-address queue) (ash 1 30))))
;;;; job control, independent listeners
(defstruct session
(lock (make-mutex :name "session lock"))
(threads nil)
(interactive-threads nil)
(interactive-threads-queue (make-waitqueue)))
(defvar *session* nil)
;;; the debugger itself tries to acquire the session lock, don't let
;;; funny situations (like getting a sigint while holding the session
;;; lock) occur
(defmacro with-session-lock ((session) &body body)
#!-sb-thread (declare (ignore session))
#!-sb-thread
`(locally ,@body)
#!+sb-thread
`(sb!sys:without-interrupts
(with-mutex ((session-lock ,session))
,@body)))
(defun new-session ()
(make-session :threads (list *current-thread*)
:interactive-threads (list *current-thread*)))
(defun init-job-control ()
(setf *session* (new-session)))
(defun %delete-thread-from-session (thread session)
(with-session-lock (session)
(setf (session-threads session)
(delete thread (session-threads session))
(session-interactive-threads session)
(delete thread (session-interactive-threads session)))))
(defun call-with-new-session (fn)
(%delete-thread-from-session *current-thread* *session*)
(let ((*session* (new-session)))
(funcall fn)))
(defmacro with-new-session (args &body forms)
(declare (ignore args)) ;for extensibility
(sb!int:with-unique-names (fb-name)
`(labels ((,fb-name () ,@forms))
(call-with-new-session (function ,fb-name)))))
;;; Remove thread from its session, if it has one.
#!+sb-thread
(defun handle-thread-exit (thread)
(with-mutex (*all-threads-lock*)
(setq *all-threads* (delete thread *all-threads*)))
(when *session*
(%delete-thread-from-session thread *session*)))
(defun terminate-session ()
#!+sb-doc
"Kill all threads in session except for this one. Does nothing if current
thread is not the foreground thread."
;; FIXME: threads created in other threads may escape termination
(let ((to-kill
(with-session-lock (*session*)
(and (eq *current-thread*
(car (session-interactive-threads *session*)))
(session-threads *session*)))))
;; do the kill after dropping the mutex; unwind forms in dying
;; threads may want to do session things
(dolist (thread to-kill)
(unless (eq thread *current-thread*)
;; terminate the thread but don't be surprised if it has
;; exited in the meantime
(handler-case (terminate-thread thread)
(interrupt-thread-error ()))))))
;;; called from top of invoke-debugger
(defun debugger-wait-until-foreground-thread (stream)
"Returns T if thread had been running in background, NIL if it was
interactive."
(declare (ignore stream))
#!-sb-thread nil
#!+sb-thread
(prog1
(with-session-lock (*session*)
(not (member *current-thread*
(session-interactive-threads *session*))))
(get-foreground)))
(defun get-foreground ()
#!-sb-thread t
#!+sb-thread
(let ((was-foreground t))
(loop
(with-session-lock (*session*)
(let ((int-t (session-interactive-threads *session*)))
(when (eq (car int-t) *current-thread*)
(unless was-foreground
(format *query-io* "Resuming thread ~A~%" *current-thread*))
(return-from get-foreground t))
(setf was-foreground nil)
(unless (member *current-thread* int-t)
(setf (cdr (last int-t))
(list *current-thread*)))
(condition-wait
(session-interactive-threads-queue *session*)
(session-lock *session*)))))))
(defun release-foreground (&optional next)
#!+sb-doc
"Background this thread. If NEXT is supplied, arrange for it to
have the foreground next"
#!-sb-thread (declare (ignore next))
#!-sb-thread nil
#!+sb-thread
(with-session-lock (*session*)
(setf (session-interactive-threads *session*)
(delete *current-thread* (session-interactive-threads *session*)))
(when next
(setf (session-interactive-threads *session*)
(list* next
(delete next (session-interactive-threads *session*)))))
(condition-broadcast (session-interactive-threads-queue *session*))))
(defun foreground-thread ()
(car (session-interactive-threads *session*)))
(defun make-listener-thread (tty-name)
(assert (probe-file tty-name))
(let* ((in (sb!unix:unix-open (namestring tty-name) sb!unix:o_rdwr #o666))
(out (sb!unix:unix-dup in))
(err (sb!unix:unix-dup in)))
(labels ((thread-repl ()
(sb!unix::unix-setsid)
(let* ((sb!impl::*stdin*
(sb!sys:make-fd-stream in :input t :buffering :line
:dual-channel-p t))
(sb!impl::*stdout*
(sb!sys:make-fd-stream out :output t :buffering :line
:dual-channel-p t))
(sb!impl::*stderr*
(sb!sys:make-fd-stream err :output t :buffering :line
:dual-channel-p t))
(sb!impl::*tty*
(sb!sys:make-fd-stream err :input t :output t
:buffering :line
:dual-channel-p t))
(sb!impl::*descriptor-handlers* nil))
(with-new-session ()
(unwind-protect
(sb!impl::toplevel-repl nil)
(sb!int:flush-standard-output-streams))))))
(make-thread #'thread-repl))))
;;;; the beef
(defun make-thread (function &key name)
#!+sb-doc
"Create a new thread of NAME that runs FUNCTION. When the function
returns the thread exits."
#!-sb-thread (declare (ignore function name))
#!-sb-thread (error "Not supported in unithread builds.")
#!+sb-thread
(let* ((thread (%make-thread :name name))
(setup-p nil)
(real-function (coerce function 'function))
(thread-sap
(%create-thread
(sb!kernel:get-lisp-obj-address
(lambda ()
;; FIXME: use semaphores?
(loop until setup-p)
;; in time we'll move some of the binding presently done in C
;; here too
(let ((*current-thread* thread)
(sb!kernel::*restart-clusters* nil)
(sb!kernel::*handler-clusters* nil)
(sb!kernel::*condition-restarts* nil)
(sb!impl::*descriptor-handlers* nil) ; serve-event
(sb!impl::*available-buffers* nil)) ;for fd-stream
;; can't use handling-end-of-the-world, because that flushes
;; output streams, and we don't necessarily have any (or we
;; could be sharing them)
(unwind-protect
(catch 'sb!impl::toplevel-catcher
(catch 'sb!impl::%end-of-the-world
(with-simple-restart
(terminate-thread
(format nil "~~@<Terminate this thread (~A)~~@:>"
*current-thread*))
;; now that most things have a chance to work
;; properly without messing up other threads, it's
;; time to enable signals
(sb!unix::reset-signal-mask)
(unwind-protect
(funcall real-function)
;; we're going down, can't handle
;; interrupts sanely anymore
(sb!unix::block-blockable-signals)))))
;; mark the thread dead, so that the gc does not
;; wait for it to handle sig-stop-for-gc
(%set-thread-state thread :dead)
;; and remove what can be the last reference to
;; the thread object
(handle-thread-exit thread)
0))
(values))))))
(when (sb!sys:sap= thread-sap (sb!sys:int-sap 0))
(error "Can't create a new thread"))
(setf (thread-%sap thread) thread-sap)
(with-mutex (*all-threads-lock*)
(push thread *all-threads*))
(with-session-lock (*session*)
(push thread (session-threads *session*)))
(setq setup-p t)
(sb!impl::finalize thread (lambda () (reap-dead-thread thread-sap)))
thread))
(defun destroy-thread (thread)
#!+sb-doc
"Deprecated. Same as TERMINATE-THREAD."
(terminate-thread thread))
(define-condition interrupt-thread-error (error)
((thread :reader interrupt-thread-error-thread :initarg :thread)
(errno :reader interrupt-thread-error-errno :initarg :errno))
#!+sb-doc
(:documentation "Interrupting thread failed.")
(:report (lambda (c s)
(format s "interrupt thread ~A failed (~A: ~A)"
(interrupt-thread-error-thread c)
(interrupt-thread-error-errno c)
(strerror (interrupt-thread-error-errno c))))))
#!+sb-doc
(setf (sb!kernel:fdocumentation 'interrupt-thread-error-thread 'function)
"The thread that was not interrupted."
(sb!kernel:fdocumentation 'interrupt-thread-error-errno 'function)
"The reason why the interruption failed.")
(defun interrupt-thread (thread function)
#!+sb-doc
"Interrupt the live THREAD and make it run FUNCTION. A moderate
degree of care is expected for use of interrupt-thread, due to its
nature: if you interrupt a thread that was holding important locks
then do something that turns out to need those locks, you probably
won't like the effect."
#!-sb-thread (declare (ignore thread))
;; not quite perfect, because it does not take WITHOUT-INTERRUPTS
;; into account
#!-sb-thread
(funcall function)
#!+sb-thread
(let ((function (coerce function 'function)))
(multiple-value-bind (res err)
(sb!unix::syscall ("interrupt_thread"
system-area-pointer sb!alien:unsigned-long)
thread
(thread-%sap thread)
(sb!kernel:get-lisp-obj-address function))
(unless res
(error 'interrupt-thread-error :thread thread :errno err)))))
(defun terminate-thread (thread)
#!+sb-doc
"Terminate the thread identified by THREAD, by causing it to run
SB-EXT:QUIT - the usual cleanup forms will be evaluated"
(interrupt-thread thread 'sb!ext:quit))
;;; internal use only. If you think you need to use this, either you
;;; are an SBCL developer, are doing something that you should discuss
;;; with an SBCL developer first, or are doing something that you
;;; should probably discuss with a professional psychiatrist first
#!+sb-thread
(defun symbol-value-in-thread (symbol thread)
(let ((thread-sap (thread-%sap thread)))
(let* ((index (sb!vm::symbol-tls-index symbol))
(tl-val (sb!sys:sap-ref-word thread-sap
(* sb!vm:n-word-bytes index))))
(if (eql tl-val sb!vm::unbound-marker-widetag)
(sb!vm::symbol-global-value symbol)
(sb!kernel:make-lisp-obj tl-val)))))

72
src/code/target-unithread.lisp
View file

@ -1,72 +0,0 @@
;;;; unithread stub support for threads in the target machine
;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; This software is derived from the CMU CL system, which was
;;;; written at Carnegie Mellon University and released into the
;;;; public domain. The software is in the public domain and is
;;;; provided with absolutely no warranty. See the COPYING and CREDITS
;;;; files for more information.
(in-package "SB!THREAD")
;;; used bu debug-int.lisp to access interrupt contexts
#!-sb-fluid (declaim (inline sb!vm::current-thread-offset-sap))
(defun sb!vm::current-thread-offset-sap (n)
(declare (type (unsigned-byte 27) n))
(sb!sys:sap-ref-sap (alien-sap (extern-alien "all_threads" (* t)))
(* n sb!vm:n-word-bytes)))
;;;; queues, locks
;; spinlocks use 0 as "free" value: higher-level locks use NIL
(defun get-spinlock (lock offset new-value)
(declare (ignore lock offset new-value)))
(defmacro with-spinlock ((queue) &body body)
(declare (ignore queue))
`(progn ,@body))
;;;; the higher-level locking operations are based on waitqueues
(defstruct waitqueue
(name nil :type (or null simple-string))
(lock 0)
(data nil))
(defstruct (mutex (:include waitqueue))
(value nil))
;;;; mutex
(defun get-mutex (lock &optional new-value (wait-p t))
(declare (type mutex lock))
(let ((old-value (mutex-value lock)))
(when (and old-value wait-p)
(error "In unithread mode, mutex ~S was requested with WAIT-P ~S and ~
new-value ~S, but has already been acquired (with value ~S)."
lock wait-p new-value old-value))
(setf (mutex-value lock) new-value)
t))
(defun release-mutex (lock)
(declare (type mutex lock))
(setf (mutex-value lock) nil))
;; FIXME need suitable stub or ERROR-signaling definitions for
;; condition-wait (queue lock)
;; condition-notify (queue)
;;;; job control
(defun init-job-control () t)
(defun debugger-wait-until-foreground-thread (stream)
(declare (ignore stream))
t)
(defun get-foreground () t)
(defun release-foreground (&optional next)
(declare (ignore next))
t)
(defun terminate-session ())

2
src/pcl/low.lisp
View file

@ -352,7 +352,7 @@
#+sb-thread
(progn
(defvar *pcl-lock* (sb-thread:make-waitqueue))
(defvar *pcl-lock* (sb-thread::make-spinlock))
(defmacro with-pcl-lock (&body body)
`(sb-thread::with-spinlock (*pcl-lock*)

5
src/runtime/thread.c
View file

@ -325,11 +325,6 @@ struct thread *create_thread(lispobj initial_function) {
else
return 0;
}
#endif
#if defined LISP_FEATURE_SB_THREAD
/* This is not needed unless #+SB-THREAD, as there's a trivial null
* unithread definition. */
/* called from lisp from the thread object finalizer */
void reap_dead_thread(struct thread *th)

56
tests/threads.impure.lisp
View file

@ -11,10 +11,29 @@
;;;; absoluely no warranty. See the COPYING and CREDITS files for
;;;; more information.
#-sb-thread (quit :unix-status 104)
(in-package "SB-THREAD") ; this is white-box testing, really
(assert (eql 1 (length (list-all-threads))))
(assert (eq *current-thread*
(find (thread-name *current-thread*) (list-all-threads)
:key #'thread-name :test #'equal)))
(assert (thread-alive-p *current-thread*))
(let ((a 0))
(interrupt-thread *current-thread* (lambda () (setq a 1)))
(assert (eql a 1)))
(let ((spinlock (make-spinlock)))
(with-spinlock (spinlock)))
(let ((mutex (make-mutex)))
(with-mutex (mutex)
mutex))
#-sb-thread (sb-ext:quit :unix-status 104)
(let ((old-threads (list-all-threads))
(thread (make-thread (lambda ()
(assert (find *current-thread* *all-threads*))
@ -68,36 +87,29 @@
(let ((l (make-mutex :name "foo"))
(p *current-thread*))
(assert (eql (mutex-value l) nil) nil "1")
(assert (eql (mutex-lock l) 0) nil "2")
(sb-thread:get-mutex l)
(assert (eql (mutex-value l) p) nil "3")
(assert (eql (mutex-lock l) 0) nil "4")
(sb-thread:release-mutex l)
(assert (eql (mutex-value l) nil) nil "5")
(assert (eql (mutex-lock l) 0) nil "6")
(describe l))
(assert (eql (mutex-value l) nil) nil "5"))
(labels ((ours-p (value)
(sb-vm:control-stack-pointer-valid-p
(sb-sys:int-sap (sb-kernel:get-lisp-obj-address value)))))
(let ((l (make-mutex :name "rec")))
(assert (eql (mutex-value l) nil) nil "1")
(assert (eql (mutex-lock l) 0) nil "2")
(sb-thread:with-recursive-lock (l)
(assert (ours-p (mutex-value l)) nil "3")
(sb-thread:with-recursive-lock (l)
(assert (ours-p (mutex-value l)) nil "4"))
(assert (ours-p (mutex-value l)) nil "5"))
(assert (eql (mutex-value l) nil) nil "6")
(assert (eql (mutex-lock l) 0) nil "7")))
(assert (eql (mutex-value l) nil) nil "6")))
(let ((l (make-waitqueue :name "spinlock"))
(let ((l (make-spinlock :name "spinlock"))
(p *current-thread*))
(assert (eql (waitqueue-lock l) 0) nil "1")
(assert (eql (spinlock-value l) 0) nil "1")
(with-spinlock (l)
(assert (eql (waitqueue-lock l) p) nil "2"))
(assert (eql (waitqueue-lock l) 0) nil "3")
(describe l))
(assert (eql (spinlock-value l) p) nil "2"))
(assert (eql (spinlock-value l) 0) nil "3"))
;; test that SLEEP actually sleeps for at least the given time, even
;; if interrupted by another thread exiting/a gc/anything
@ -108,7 +120,8 @@
(let ((queue (make-waitqueue :name "queue"))
(lock (make-mutex :name "lock")))
(lock (make-mutex :name "lock"))
(n 0))
(labels ((in-new-thread ()
(with-mutex (lock)
(assert (eql (mutex-value lock) *current-thread*))
@ -116,14 +129,16 @@
;; now drop it and sleep
(condition-wait queue lock)
;; after waking we should have the lock again
(assert (eql (mutex-value lock) *current-thread*)))))
(assert (eql (mutex-value lock) *current-thread*))
(assert (eql n 1))
(decf n))))
(make-thread #'in-new-thread)
(sleep 2) ; give it a chance to start
;; check the lock is free while it's asleep
(format t "parent thread ~A~%" *current-thread*)
(assert (eql (mutex-value lock) nil))
(assert (eql (mutex-lock lock) 0))
(with-mutex (lock)
(incf n)
(condition-notify queue))
(sleep 1)))
@ -146,7 +161,6 @@
;; check the lock is free while it's asleep
(format t "parent thread ~A~%" *current-thread*)
(assert (eql (mutex-value lock) nil))
(assert (eql (mutex-lock lock) 0))
(with-recursive-lock (lock)
(condition-notify queue))
(sleep 1)))
@ -272,11 +286,11 @@
(let (a-done b-done)
(make-thread (lambda ()
(dotimes (i 100)
(dotimes (i 100)
(sb-ext:gc) (princ "\\") (force-output))
(setf a-done t)))
(make-thread (lambda ()
(dotimes (i 25)
(dotimes (i 25)
(sb-ext:gc :full t)
(princ "/") (force-output))
(setf b-done t)))

2
version.lisp-expr
View file

@ -17,4 +17,4 @@
;;; checkins which aren't released. (And occasionally for internal
;;; versions, especially for internal versions off the main CVS
;;; branch, it gets hairier, e.g. "0.pre7.14.flaky4.13".)
"0.9.2.37"
"0.9.2.38"