by the Win32 port for emulating fork()). As of Perl 5.8.0, ithreads has
become the standard threading model for Perl.
-If you really want the older support for threads described below,
-it is enabled with:
-
- sh Configure -Dusethreads -Duse5005threads
-
-Be warned that the old 5.005 implementation of threads is known
-to be quite buggy, and unmaintained, which means that the bugs
-are there to stay. (We are not mean by not fixing the bugs:
-the bugs are just really, really, really hard to fix. Honest.)
-
-The rest of this document only applies to the use5005threads style of
-threads, and the comments on what works on which platform are highly
-obsolete and preserved here for archaeology buffs only. The
-architecture specific hints files do all the necessary option
-tweaking automatically during Configure, both for the 5.005 threads
-and for the new interpreter threads.
-
----------------------------------------------------------------------------
-
-Support for threading is still in the highly experimental stages. There
-are known race conditions that show up under high contention on SMP
-machines. Internal implementation is still subject to changes.
-It is not recommended for production use at this time.
-
----------------------------------------------------------------------------
-
-Building
-
-If your system is in the following list you should be able to just:
-
- ./Configure -Dusethreads -Duse5005threads -des
- make
-
-and ignore the rest of this "Building" section. If not, continue
-from the "Problems" section.
-
- * Linux 2.* (with the LinuxThreads library installed:
- that's the linuxthreads and linuxthreads-devel RPMs
- for RedHat)
-
- * Tru64 UNIX (formerly Digital UNIX formerly DEC OSF/1)
- (see additional note below)
-
- * Solaris 2.* for recentish x (2.5 is OK)
-
- * IRIX 6.2 or newer. 6.2 will require a few OS patches.
- IMPORTANT: Without patch 2401 (or its replacement),
- a kernel bug in IRIX 6.2 will cause your machine to
- panic and crash when running threaded perl.
- IRIX 6.3 and up should be OK. See lower down for patch details.
-
- * AIX 4.1.5 or newer.
-
- * FreeBSD 2.2.8 or newer.
-
- * OpenBSD
-
- * NeXTstep, OpenStep
-
- * OS/2
-
- * DOS DJGPP
-
- * VM/ESA
-
----------------------------------------------------------------------------
-
-Problems
-
-If the simple way doesn't work or you are using another platform which
-you believe supports POSIX.1c threads then read on. Additional
-information may be in a platform-specific "hints" file in the hints/
-subdirectory.
-
-On platforms that use Configure to build perl, omit the -d from your
-./Configure arguments. For example, use:
-
- ./Configure -Dusethreads -Duse5005threads
-
-When Configure prompts you for ccflags, insert any other arguments in
-there that your compiler needs to use POSIX threads (-D_REENTRANT,
--pthreads, -threads, -pthread, -thread, are good guesses). When
-Configure prompts you for linking flags, include any flags required
-for threading (usually nothing special is required here). Finally,
-when Configure prompts you for libraries, include any necessary
-libraries (e.g. -lpthread). Pay attention to the order of libraries.
-It is probably necessary to specify your threading library *before*
-your standard C library, e.g. it might be necessary to have -lpthread
--lc, instead of -lc -lpthread. You may also need to use -lc_r instead
-of -lc.
-
-Once you have specified all your compiler flags, you can have Configure
-accept all the defaults for the remainder of the session by typing &-d
-at any Configure prompt.
-
-Some additional notes (some of these may be obsolete now, other items
-may be handled automatically):
-
-For Digital Unix 4.x:
- Add -pthread to ccflags
- Add -pthread to ldflags
- Add -lpthread -lc_r to lddlflags
-
- For some reason, the extra includes for pthreads make Digital UNIX
- complain fatally about the sbrk() declaration in perl's malloc.c
- so use the native malloc, e.g. sh Configure -Uusemymalloc, or
- manually edit your config.sh as follows:
- Change usemymalloc to n
- Zap mallocobj and mallocsrc (foo='')
- Change d_mymalloc to undef
-
-For Digital Unix 3.x (Formerly DEC OSF/1):
- Add -DOLD_PTHREADS_API to ccflags
- If compiling with the GNU cc compiler, remove -threads from ccflags
-
- (The following should be done automatically if you call Configure
- with the -Dusethreads option).
- Add -lpthread -lmach -lc_r to libs (in the order specified).
-
-For IRIX:
- (This should all be done automatically by the hint file).
- Add -lpthread to libs
- For IRIX 6.2, you have to have the following patches installed:
- 1404 Irix 6.2 Posix 1003.1b man pages
- 1645 IRIX 6.2 & 6.3 POSIX header file updates
- 2000 Irix 6.2 Posix 1003.1b support modules
- 2254 Pthread library fixes
- 2401 6.2 all platform kernel rollup
- IMPORTANT: Without patch 2401, a kernel bug in IRIX 6.2 will
- cause your machine to panic and crash when running threaded perl.
- IRIX 6.3 and up should be OK.
-
- For IRIX 6.3 and 6.4 the pthreads should work out of the box.
- Thanks to Hannu Napari <Hannu.Napari@hut.fi> for the IRIX
- pthreads patches information.
-
-For AIX:
- (This should all be done automatically by the hint file).
- Change cc to xlc_r or cc_r.
- Add -DNEED_PTHREAD_INIT to ccflags and cppflags
- Add -lc_r to libswanted
- Change -lc in lddflags to be -lpthread -lc_r -lc
-
-For Win32:
- See README.win32, and the notes at the beginning of win32/Makefile
- or win32/makefile.mk.
-
-Now you can do a
- make
-
-When you succeed in compiling and testing ("make test" after your
-build) a threaded Perl in a platform previously unknown to support
-threaded perl, please let perlbug@perl.com know about your victory.
-Explain what you did in painful detail.
-
----------------------------------------------------------------------------
-
-O/S specific bugs
-
-Irix 6.2: See the Irix warning above.
-
-LinuxThreads 0.5 has a bug which can cause file descriptor 0 to be
-closed after a fork() leading to many strange symptoms. Version 0.6
-has this fixed but the following patch can be applied to 0.5 for now:
-
------------------------------ cut here -----------------------------
---- linuxthreads-0.5/pthread.c.ORI Mon Oct 6 13:55:50 1997
-+++ linuxthreads-0.5/pthread.c Mon Oct 6 13:57:24 1997
-@@ -312,8 +312,10 @@
- free(pthread_manager_thread_bos);
- pthread_manager_thread_bos = pthread_manager_thread_tos = NULL;
- /* Close the two ends of the pipe */
-- close(pthread_manager_request);
-- close(pthread_manager_reader);
-+ if (pthread_manager_request >= 0) {
-+ close(pthread_manager_request);
-+ close(pthread_manager_reader);
-+ }
- pthread_manager_request = pthread_manager_reader = -1;
- /* Update the pid of the main thread */
- self->p_pid = getpid();
------------------------------ cut here -----------------------------
-
-
-Building the Thread extension
-
-The Thread extension is now part of the main perl distribution tree.
-If you did Configure -Dusethreads -Duse5005threads then it will have been
-added to the list of extensions automatically.
-
-You can try some of the tests with
- cd ext/Thread
- perl create.t
- perl join.t
- perl lock.t
- perl io.t
-etc.
-The io one leaves a thread reading from the keyboard on stdin so
-as the ping messages appear you can type lines and see them echoed.
-
-Try running the main perl test suite too. There are known
-failures for some of the DBM/DB extensions (if their underlying
-libraries were not compiled to be thread-aware).
-
----------------------------------------------------------------------------
-
-Bugs
-
-* FAKE_THREADS should produce a working perl but the Thread
-extension won't build with it yet. (FAKE_THREADS has not been
-tested at all in recent times.)
-
-* There may still be races where bugs show up under contention.
-
----------------------------------------------------------------------------
-
-Debugging
-
-Use the -DS command-line option to turn on debugging of the
-multi-threading code. Under Linux, that also turns on a quick
-hack I did to grab a bit of extra information from segfaults.
-If you have a fancier gdb/threads setup than I do then you'll
-have to delete the lines in perl.c which say
- #if defined(DEBUGGING) && defined(USE_5005THREADS) && defined(__linux__)
- DEBUG_S(signal(SIGSEGV, (void(*)(int))catch_sigsegv););
- #endif
-
----------------------------------------------------------------------------
-
-Background
-
-Some old globals (e.g. stack_sp, op) and some old per-interpreter
-variables (e.g. tmps_stack, cxstack) move into struct thread.
-All fields of struct thread which derived from original perl
-variables have names of the form Tfoo. For example, stack_sp becomes
-the field Tstack_sp of struct thread. For those fields which moved
-from original perl, thread.h does
- #define foo (thr->Tfoo)
-This means that all functions in perl which need to use one of these
-fields need an (automatic) variable thr which points at the current
-thread's struct thread. For pp_foo functions, it is passed around as
-an argument, for other functions they do
- dTHR;
-which declares and initialises thr from thread-specific data
-via pthread_getspecific. If a function fails to compile with an
-error about "no such variable thr", it probably just needs a dTHR
-at the top.
-
-
-Fake threads
-
-For FAKE_THREADS, thr is a global variable and perl schedules threads
-by altering thr in between appropriate ops. The next and prev fields
-of struct thread keep all fake threads on a doubly linked list and
-the next_run and prev_run fields keep all runnable threads on a
-doubly linked list. Mutexes are stubs for FAKE_THREADS. Condition
-variables are implemented as a list of waiting threads.
-
-
-Mutexes and condition variables
-
-The API is via macros MUTEX_{INIT,LOCK,UNLOCK,DESTROY} and
-COND_{INIT,WAIT,SIGNAL,BROADCAST,DESTROY}.
-
-A mutex is only required to be a simple, fast mutex (e.g. it does not
-have to be recursive). It is only ever held across very short pieces
-of code. Condition variables are only ever signalled/broadcast while
-their associated mutex is held. (This constraint simplifies the
-implementation of condition variables in certain porting situations.)
-For POSIX threads, perl mutexes and condition variables correspond to
-POSIX ones. For FAKE_THREADS, mutexes are stubs and condition variables
-are implemented as lists of waiting threads. For FAKE_THREADS, a thread
-waits on a condition variable by removing itself from the runnable
-list, calling SCHEDULE to change thr to the next appropriate
-runnable thread and returning op (i.e. the new threads next op).
-This means that fake threads can only block while in PP code.
-A PP function which contains a COND_WAIT must be prepared to
-handle such restarts and can use the field "private" of struct
-thread to record its state. For fake threads, COND_SIGNAL and
-COND_BROADCAST work by putting back all the threads on the
-condition variables list into the run queue. Note that a mutex
-must *not* be held while returning from a PP function.
-
-Perl locks and condition variables are both implemented as a
-condpair_t structure, containing a mutex, an "owner" condition
-variable, an owner thread field and another condition variable).
-The structure is attached by 'm' magic to any SV. pp_lock locks
-such an object by waiting on the ownercond condition variable until
-the owner field is zero and then setting the owner field to its own
-thread pointer. The lock is semantically recursive so if the owner
-field already matches the current thread then pp_lock returns
-straight away. If the owner field has to be filled in then
-unlock_condpair is queued as an end-of-block destructor and
-that function zeroes out the owner field and signals the ownercond
-condition variable, thus waking up any other thread that wants to
-lock it. When used as a condition variable, the condpair is locked
-(involving the above wait-for-ownership and setting the owner field)
-and the spare condition variable field is used for waiting on.
-
-
-Thread states
-
-
- $t->join
-R_JOINABLE ---------------------> R_JOINED >----\
- | \ pthread_join(t) | ^ |
- | \ | | join | pthread_join
- | \ | | |
- | \ | \------/
- | \ |
- | \ |
- | $t->detach\ pthread_detach |
- | _\| |
-ends| R_DETACHED ends | unlink
- | \ |
- | ends \ unlink |
- | \ |
- | \ |
- | \ |
- | \ |
- | \ |
- V join detach _\| V
-ZOMBIE ----------------------------> DEAD
- pthread_join pthread_detach
- and unlink and unlink
-
-
+As of 5.9.0, the older threading model is not supported anymore.
Malcolm Beattie
mbeattie@sable.ox.ac.uk
More platforms added 26 Jul 1999 by
Jarkko Hietaniemi
+
+Removed 5005threads support 03 Oct 2002 by
+H.Merijn Brand
projects / p5sagit/p5-mst-13.2.git / blobdiff