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1 | Building |
2 | ||
d81a1b93 | 3 | If you want to build with multi-threading support and you are |
69ce17de | 4 | running one of the following: |
e2198c6b | 5 | |
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6 | * Linux 2.x (with the LinuxThreads library installed: that's |
7 | the linuxthreads and linuxthreads-devel RPMs for RedHat) | |
8 | ||
9 | * Digital UNIX 4.x | |
10 | ||
11 | * Solaris 2.x for recentish x (2.5 is OK) | |
12 | ||
13 | * IRIX 6.2 or newer. 6.2 will require a few os patches. | |
14 | IMPORTANT: Without patch 2401, a kernel bug in IRIX 6.2 will | |
15 | cause your machine to panic and crash when running threaded perl. | |
16 | IRIX 6.3 and up should be OK. See lower down for patch details. | |
17 | ||
d81a1b93 | 18 | then you should be able to use |
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19 | |
20 | ./Configure -Dusethreads -des | |
d81a1b93 | 21 | make |
e2198c6b | 22 | |
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23 | and ignore the rest of this "Building" section. If it doesn't |
24 | work or you are using another platform which you believe supports | |
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25 | POSIX.1c threads then read on. Additional information may be in |
26 | a platform-specific "hints" file in the hints/ subdirectory. | |
27 | ||
28 | Omit the -d from your ./Configure arguments. For example, use | |
29 | ||
30 | ./Configure -Dusethreads | |
31 | ||
32 | When Configure prompts you for ccflags, insert any other arguments in | |
33 | there that your compiler needs to use POSIX threads. When Configure | |
34 | prompts you for linking flags, include any flags required for | |
35 | threading (usually nothing special is required here). Finally, when | |
36 | COnfigure prompts you for libraries, include any necessary libraries | |
37 | (e.g. -lpthread). Pay attention to the order of libraries. It is | |
38 | probably necessary to specify your threading library *before* your | |
39 | standard C library, e.g. it might be necessary to have -lpthread -lc, | |
40 | instead of -lc -lpthread. | |
41 | ||
42 | Once you have specified all your compiler flags, you can have Configure | |
43 | accept all the defaults for the remainder of the session by typing &-d | |
44 | at any Configure prompt. | |
45 | ||
46 | Some additional notes (some of these may be obsolete now, other items | |
47 | may be handled automatically): | |
48 | ||
72aaf631 | 49 | For Digital Unix 4.x: |
e2198c6b | 50 | Add -pthread to ccflags |
72aaf631 | 51 | Add -pthread to ldflags |
d81a1b93 | 52 | Add -lpthread -lc_r to lddlflags |
e2198c6b | 53 | |
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54 | For some reason, the extra includes for pthreads make Digital UNIX |
55 | complain fatally about the sbrk() delcaration in perl's malloc.c | |
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56 | so use the native malloc, e.g. sh Configure -Uusemymalloc, or |
57 | manually edit your config.sh as follows: | |
58 | Change usemymalloc to n | |
59 | Zap mallocobj and mallocsrc (foo='') | |
60 | Change d_mymalloc to undef | |
61 | ||
eb1cfdd6 | 62 | For IRIX: |
e2198c6b | 63 | (This should all be done automatically by the hint file). |
eb1cfdd6 | 64 | Add -lpthread to libs |
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65 | For IRIX 6.2, you have to have the following patches installed: |
66 | 1404 Irix 6.2 Posix 1003.1b man pages | |
67 | 1645 IRIX 6.2 & 6.3 POSIX header file updates | |
68 | 2000 Irix 6.2 Posix 1003.1b support modules | |
69 | 2254 Pthread library fixes | |
69ce17de MB |
70 | 2401 6.2 all platform kernel rollup |
71 | IMPORTANT: Without patch 2401, a kernel bug in IRIX 6.2 will | |
72 | cause your machine to panic and crash when running threaded perl. | |
73 | IRIX 6.3 and up should be OK. | |
74 | ||
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75 | For IRIX 6.3 and 6.4 the pthreads should work out of the box. |
76 | Thanks to Hannu Napari <Hannu.Napari@hut.fi> for the IRIX | |
77 | pthreads patches information. | |
ce637636 | 78 | For AIX: |
e2198c6b | 79 | (This should all be done automatically by the hint file). |
ce637636 | 80 | Change cc to xlc_r or cc_r. |
e2198c6b | 81 | Add -DNEED_PTHREAD_INIT to ccflags and cppflags |
ce637636 JH |
82 | Add -lc_r to libswanted |
83 | Change -lc in lddflags to be -lpthread -lc_r -lc | |
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84 | |
85 | Now you can do a | |
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86 | make |
87 | ||
72aaf631 | 88 | |
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89 | O/S specific bugs |
90 | ||
e2198c6b | 91 | Irix 6.2: See the Irix warning above. |
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92 | |
93 | LinuxThreads 0.5 has a bug which can cause file descriptor 0 to be | |
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94 | closed after a fork() leading to many strange symptoms. Version 0.6 |
95 | has this fixed but the following patch can be applied to 0.5 for now: | |
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96 | |
97 | ----------------------------- cut here ----------------------------- | |
98 | --- linuxthreads-0.5/pthread.c.ORI Mon Oct 6 13:55:50 1997 | |
99 | +++ linuxthreads-0.5/pthread.c Mon Oct 6 13:57:24 1997 | |
100 | @@ -312,8 +312,10 @@ | |
101 | free(pthread_manager_thread_bos); | |
102 | pthread_manager_thread_bos = pthread_manager_thread_tos = NULL; | |
103 | /* Close the two ends of the pipe */ | |
104 | - close(pthread_manager_request); | |
105 | - close(pthread_manager_reader); | |
106 | + if (pthread_manager_request >= 0) { | |
107 | + close(pthread_manager_request); | |
108 | + close(pthread_manager_reader); | |
109 | + } | |
110 | pthread_manager_request = pthread_manager_reader = -1; | |
111 | /* Update the pid of the main thread */ | |
112 | self->p_pid = getpid(); | |
113 | ----------------------------- cut here ----------------------------- | |
114 | ||
115 | ||
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116 | Building the Thread extension |
117 | ||
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118 | The Thread extension is now part of the main perl distribution tree. |
119 | If you did Configure -Dusethreads then it will have been added to | |
120 | the list of extensions automatically. | |
72aaf631 | 121 | |
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122 | You can try some of the tests with |
123 | cd ext/Thread | |
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124 | perl create.t |
125 | perl join.t | |
126 | perl lock.t | |
127 | perl io.t | |
128 | etc. | |
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129 | The io one leaves a thread reading from the keyboard on stdin so |
130 | as the ping messages appear you can type lines and see them echoed. | |
131 | ||
132 | Try running the main perl test suite too. There are known | |
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133 | failures for some of the DBM/DB extensions (if their underlying |
134 | libraries were not compiled to be thread-aware). | |
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135 | |
136 | ||
137 | Bugs | |
138 | ||
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139 | * FAKE_THREADS should produce a working perl but the Thread |
140 | extension won't build with it yet. | |
141 | ||
142 | * There's a known memory leak (curstack isn't freed at the end | |
143 | of each thread because it causes refcount problems that I | |
144 | haven't tracked down yet) and there are very probably others too. | |
145 | ||
5756a3ac | 146 | * There may still be races where bugs show up under contention. |
72aaf631 | 147 | |
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148 | * Need to document "lock", Thread.pm, Queue.pm, ... |
149 | ||
72aaf631 | 150 | |
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151 | Debugging |
152 | ||
153 | Use the -DL command-line option to turn on debugging of the | |
154 | multi-threading code. Under Linux, that also turns on a quick | |
155 | hack I did to grab a bit of extra information from segfaults. | |
156 | If you have a fancier gdb/threads setup than I do then you'll | |
157 | have to delete the lines in perl.c which say | |
158 | #if defined(DEBUGGING) && defined(USE_THREADS) && defined(__linux__) | |
159 | DEBUG_L(signal(SIGSEGV, (void(*)(int))catch_sigsegv);); | |
160 | #endif | |
161 | ||
162 | ||
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163 | Background |
164 | ||
165 | Some old globals (e.g. stack_sp, op) and some old per-interpreter | |
166 | variables (e.g. tmps_stack, cxstack) move into struct thread. | |
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167 | All fields of struct thread which derived from original perl |
168 | variables have names of the form Tfoo. For example, stack_sp becomes | |
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169 | the field Tstack_sp of struct thread. For those fields which moved |
170 | from original perl, thread.h does | |
171 | #define foo (thr->Tfoo) | |
172 | This means that all functions in perl which need to use one of these | |
173 | fields need an (automatic) variable thr which points at the current | |
174 | thread's struct thread. For pp_foo functions, it is passed around as | |
175 | an argument, for other functions they do | |
176 | dTHR; | |
177 | which declares and initialises thr from thread-specific data | |
178 | via pthread_getspecific. If a function fails to compile with an | |
179 | error about "no such variable thr", it probably just needs a dTHR | |
180 | at the top. | |
181 | ||
182 | ||
183 | Fake threads | |
184 | ||
185 | For FAKE_THREADS, thr is a global variable and perl schedules threads | |
186 | by altering thr in between appropriate ops. The next and prev fields | |
187 | of struct thread keep all fake threads on a doubly linked list and | |
188 | the next_run and prev_run fields keep all runnable threads on a | |
189 | doubly linked list. Mutexes are stubs for FAKE_THREADS. Condition | |
190 | variables are implemented as a list of waiting threads. | |
191 | ||
192 | ||
193 | Mutexes and condition variables | |
194 | ||
195 | The API is via macros MUTEX_{INIT,LOCK,UNLOCK,DESTROY} and | |
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196 | COND_{INIT,WAIT,SIGNAL,BROADCAST,DESTROY}. |
197 | ||
198 | A mutex is only required to be a simple, fast mutex (e.g. it does not | |
199 | have to be recursive). It is only ever held across very short pieces | |
200 | of code. Condition variables are only ever signalled/broadcast while | |
201 | their associated mutex is held. (This constraint simplifies the | |
202 | implementation of condition variables in certain porting situations.) | |
203 | For POSIX threads, perl mutexes and condition variables correspond to | |
204 | POSIX ones. For FAKE_THREADS, mutexes are stubs and condition variables | |
205 | are implmented as lists of waiting threads. For FAKE_THREADS, a thread | |
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206 | waits on a condition variable by removing itself from the runnable |
207 | list, calling SCHEDULE to change thr to the next appropriate | |
208 | runnable thread and returning op (i.e. the new threads next op). | |
209 | This means that fake threads can only block while in PP code. | |
210 | A PP function which contains a COND_WAIT must be prepared to | |
211 | handle such restarts and can use the field "private" of struct | |
212 | thread to record its state. For fake threads, COND_SIGNAL and | |
213 | COND_BROADCAST work by putting back all the threads on the | |
214 | condition variables list into the run queue. Note that a mutex | |
215 | must *not* be held while returning from a PP function. | |
216 | ||
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217 | Perl locks and condition variables are both implemented as a |
218 | condpair_t structure, containing a mutex, an "owner" condition | |
219 | variable, an owner thread field and another condition variable). | |
220 | The structure is attached by 'm' magic to any SV. pp_lock locks | |
221 | such an object by waiting on the ownercond condition variable until | |
222 | the owner field is zero and then setting the owner field to its own | |
223 | thread pointer. The lock is semantically recursive so if the owner | |
224 | field already matches the current thread then pp_lock returns | |
225 | straight away. If the owner field has to be filled in then | |
226 | unlock_condpair is queued as an end-of-block destructor and | |
227 | that function zeroes out the owner field and signals the ownercond | |
228 | condition variable, thus waking up any other thread that wants to | |
229 | lock it. When used as a condition variable, the condpair is locked | |
230 | (involving the above wait-for-ownership and setting the owner field) | |
231 | and the spare condition variable field is used for waiting on. | |
232 | ||
233 | ||
234 | Thread states | |
235 | ||
236 | ||
237 | $t->join | |
238 | R_JOINABLE ---------------------> R_JOINED >----\ | |
239 | | \ pthread_join(t) | ^ | | |
240 | | \ | | join | pthread_join | |
241 | | \ | | | | |
242 | | \ | \------/ | |
243 | | \ | | |
244 | | \ | | |
245 | | $t->detach\ pthread_detach | | |
246 | | _\| | | |
247 | ends| R_DETACHED ends | unlink | |
248 | | \ | | |
249 | | ends \ unlink | | |
250 | | \ | | |
251 | | \ | | |
252 | | \ | | |
253 | | \ | | |
254 | | \ | | |
255 | V join detach _\| V | |
256 | ZOMBIE ----------------------------> DEAD | |
257 | pthread_join pthread_detach | |
258 | and unlink and unlink | |
259 | ||
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260 | |
261 | ||
72aaf631 MB |
262 | Malcolm Beattie |
263 | mbeattie@sable.ox.ac.uk | |
69ce17de | 264 | Last updated: 27 November 1997 |
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265 | |
266 | Configure-related info updated 16 July 1998 by | |
267 | Andy Dougherty <doughera@lafayette.edu> |