Guido van Rossum | 7f5013a | 1998-04-09 22:01:42 +0000 | [diff] [blame] | 1 | # threading.py: |
| 2 | # Proposed new threading module, emulating a subset of Java's threading model |
| 3 | |
| 4 | import sys |
| 5 | import time |
| 6 | import thread |
| 7 | import traceback |
| 8 | import StringIO |
| 9 | |
| 10 | # Rename some stuff so "from threading import *" is safe |
| 11 | |
| 12 | _sys = sys |
| 13 | del sys |
| 14 | |
| 15 | _time = time.time |
| 16 | _sleep = time.sleep |
| 17 | del time |
| 18 | |
| 19 | _start_new_thread = thread.start_new_thread |
| 20 | _allocate_lock = thread.allocate_lock |
| 21 | _get_ident = thread.get_ident |
| 22 | del thread |
| 23 | |
| 24 | _print_exc = traceback.print_exc |
| 25 | del traceback |
| 26 | |
| 27 | _StringIO = StringIO.StringIO |
| 28 | del StringIO |
| 29 | |
| 30 | |
| 31 | # Debug support (adapted from ihooks.py) |
| 32 | |
| 33 | _VERBOSE = 0 |
| 34 | |
| 35 | if __debug__: |
| 36 | |
| 37 | class _Verbose: |
| 38 | |
| 39 | def __init__(self, verbose=None): |
| 40 | if verbose is None: |
| 41 | verbose = _VERBOSE |
| 42 | self.__verbose = verbose |
| 43 | |
| 44 | def _note(self, format, *args): |
| 45 | if self.__verbose: |
| 46 | format = format % args |
| 47 | format = "%s: %s\n" % ( |
| 48 | currentThread().getName(), format) |
| 49 | _sys.stderr.write(format) |
| 50 | |
| 51 | else: |
| 52 | # Disable this when using "python -O" |
| 53 | class _Verbose: |
| 54 | def __init__(self, verbose=None): |
| 55 | pass |
| 56 | def _note(self, *args): |
| 57 | pass |
| 58 | |
| 59 | |
| 60 | # Synchronization classes |
| 61 | |
| 62 | Lock = _allocate_lock |
| 63 | |
| 64 | def RLock(*args, **kwargs): |
| 65 | return apply(_RLock, args, kwargs) |
| 66 | |
| 67 | class _RLock(_Verbose): |
| 68 | |
| 69 | def __init__(self, verbose=None): |
| 70 | _Verbose.__init__(self, verbose) |
| 71 | self.__block = _allocate_lock() |
| 72 | self.__owner = None |
| 73 | self.__count = 0 |
| 74 | |
| 75 | def __repr__(self): |
| 76 | return "<%s(%s, %d)>" % ( |
| 77 | self.__class__.__name__, |
| 78 | self.__owner and self.__owner.getName(), |
| 79 | self.__count) |
| 80 | |
| 81 | def acquire(self, blocking=1): |
| 82 | me = currentThread() |
| 83 | if self.__owner is me: |
| 84 | self.__count = self.__count + 1 |
| 85 | if __debug__: |
| 86 | self._note("%s.acquire(%s): recursive success", self, blocking) |
| 87 | return 1 |
| 88 | rc = self.__block.acquire(blocking) |
| 89 | if rc: |
| 90 | self.__owner = me |
| 91 | self.__count = 1 |
| 92 | if __debug__: |
| 93 | self._note("%s.acquire(%s): initial succes", self, blocking) |
| 94 | else: |
| 95 | if __debug__: |
| 96 | self._note("%s.acquire(%s): failure", self, blocking) |
| 97 | return rc |
| 98 | |
| 99 | def release(self): |
| 100 | me = currentThread() |
| 101 | assert self.__owner is me, "release() of un-acquire()d lock" |
| 102 | self.__count = count = self.__count - 1 |
| 103 | if not count: |
| 104 | self.__owner = None |
| 105 | self.__block.release() |
| 106 | if __debug__: |
| 107 | self._note("%s.release(): final release", self) |
| 108 | else: |
| 109 | if __debug__: |
| 110 | self._note("%s.release(): non-final release", self) |
| 111 | |
| 112 | # Internal methods used by condition variables |
| 113 | |
| 114 | def _acquire_restore(self, (count, owner)): |
| 115 | self.__block.acquire() |
| 116 | self.__count = count |
| 117 | self.__owner = owner |
| 118 | if __debug__: |
| 119 | self._note("%s._acquire_restore()", self) |
| 120 | |
| 121 | def _release_save(self): |
| 122 | if __debug__: |
| 123 | self._note("%s._release_save()", self) |
| 124 | count = self.__count |
| 125 | self.__count = 0 |
| 126 | owner = self.__owner |
| 127 | self.__owner = None |
| 128 | self.__block.release() |
| 129 | return (count, owner) |
| 130 | |
| 131 | def _is_owned(self): |
| 132 | return self.__owner is currentThread() |
| 133 | |
| 134 | |
| 135 | def Condition(*args, **kwargs): |
| 136 | return apply(_Condition, args, kwargs) |
| 137 | |
| 138 | class _Condition(_Verbose): |
| 139 | |
| 140 | def __init__(self, lock=None, verbose=None): |
| 141 | _Verbose.__init__(self, verbose) |
| 142 | if lock is None: |
| 143 | lock = RLock() |
| 144 | self.__lock = lock |
| 145 | # Export the lock's acquire() and release() methods |
| 146 | self.acquire = lock.acquire |
| 147 | self.release = lock.release |
| 148 | # If the lock defines _release_save() and/or _acquire_restore(), |
| 149 | # these override the default implementations (which just call |
| 150 | # release() and acquire() on the lock). Ditto for _is_owned(). |
| 151 | try: |
| 152 | self._release_save = lock._release_save |
| 153 | except AttributeError: |
| 154 | pass |
| 155 | try: |
| 156 | self._acquire_restore = lock._acquire_restore |
| 157 | except AttributeError: |
| 158 | pass |
| 159 | try: |
| 160 | self._is_owned = lock._is_owned |
| 161 | except AttributeError: |
| 162 | pass |
| 163 | self.__waiters = [] |
| 164 | |
| 165 | def __repr__(self): |
| 166 | return "<Condition(%s, %d)>" % (self.__lock, len(self.__waiters)) |
| 167 | |
| 168 | def _release_save(self): |
| 169 | self.__lock.release() # No state to save |
| 170 | |
| 171 | def _acquire_restore(self, x): |
| 172 | self.__lock.acquire() # Ignore saved state |
| 173 | |
| 174 | def _is_owned(self): |
| 175 | if self.__lock.acquire(0): |
| 176 | self.__lock.release() |
| 177 | return 0 |
| 178 | else: |
| 179 | return 1 |
| 180 | |
| 181 | def wait(self, timeout=None): |
| 182 | me = currentThread() |
| 183 | assert self._is_owned(), "wait() of un-acquire()d lock" |
| 184 | waiter = _allocate_lock() |
| 185 | waiter.acquire() |
| 186 | self.__waiters.append(waiter) |
| 187 | saved_state = self._release_save() |
| 188 | if timeout is None: |
| 189 | waiter.acquire() |
| 190 | if __debug__: |
| 191 | self._note("%s.wait(): got it", self) |
| 192 | else: |
| 193 | endtime = _time() + timeout |
| 194 | delay = 0.000001 # 1 usec |
| 195 | while 1: |
| 196 | gotit = waiter.acquire(0) |
| 197 | if gotit or _time() >= endtime: |
| 198 | break |
| 199 | _sleep(delay) |
| 200 | if delay < 1.0: |
| 201 | delay = delay * 2.0 |
| 202 | if not gotit: |
| 203 | if __debug__: |
| 204 | self._note("%s.wait(%s): timed out", self, timeout) |
| 205 | try: |
| 206 | self.__waiters.remove(waiter) |
| 207 | except ValueError: |
| 208 | pass |
| 209 | else: |
| 210 | if __debug__: |
| 211 | self._note("%s.wait(%s): got it", self, timeout) |
| 212 | self._acquire_restore(saved_state) |
| 213 | |
| 214 | def notify(self, n=1): |
| 215 | me = currentThread() |
| 216 | assert self._is_owned(), "notify() of un-acquire()d lock" |
| 217 | __waiters = self.__waiters |
| 218 | waiters = __waiters[:n] |
| 219 | if not waiters: |
| 220 | if __debug__: |
| 221 | self._note("%s.notify(): no waiters", self) |
| 222 | return |
| 223 | self._note("%s.notify(): notifying %d waiter%s", self, n, |
| 224 | n!=1 and "s" or "") |
| 225 | for waiter in waiters: |
| 226 | waiter.release() |
| 227 | try: |
| 228 | __waiters.remove(waiter) |
| 229 | except ValueError: |
| 230 | pass |
| 231 | |
| 232 | def notifyAll(self): |
| 233 | self.notify(len(self.__waiters)) |
| 234 | |
| 235 | |
| 236 | def Semaphore(*args, **kwargs): |
| 237 | return apply(_Semaphore, args, kwargs) |
| 238 | |
| 239 | class _Semaphore(_Verbose): |
| 240 | |
| 241 | # After Tim Peters' semaphore class, but bnot quite the same (no maximum) |
| 242 | |
| 243 | def __init__(self, value=1, verbose=None): |
| 244 | assert value >= 0, "Semaphore initial value must be >= 0" |
| 245 | _Verbose.__init__(self, verbose) |
| 246 | self.__cond = Condition(Lock()) |
| 247 | self.__value = value |
| 248 | |
| 249 | def acquire(self, blocking=1): |
| 250 | rc = 0 |
| 251 | self.__cond.acquire() |
| 252 | while self.__value == 0: |
| 253 | if not blocking: |
| 254 | break |
| 255 | self.__cond.wait() |
| 256 | else: |
| 257 | self.__value = self.__value - 1 |
| 258 | rc = 1 |
| 259 | self.__cond.release() |
| 260 | return rc |
| 261 | |
| 262 | def release(self): |
| 263 | self.__cond.acquire() |
| 264 | self.__value = self.__value + 1 |
| 265 | self.__cond.notify() |
| 266 | self.__cond.release() |
| 267 | |
| 268 | |
| 269 | def Event(*args, **kwargs): |
| 270 | return apply(_Event, args, kwargs) |
| 271 | |
| 272 | class _Event(_Verbose): |
| 273 | |
| 274 | # After Tim Peters' event class (without is_posted()) |
| 275 | |
| 276 | def __init__(self, verbose=None): |
| 277 | _Verbose.__init__(self, verbose) |
| 278 | self.__cond = Condition(Lock()) |
| 279 | self.__flag = 0 |
| 280 | |
| 281 | def isSet(self): |
| 282 | return self.__flag |
| 283 | |
| 284 | def set(self): |
| 285 | self.__cond.acquire() |
| 286 | self.__flag = 1 |
| 287 | self.__cond.notifyAll() |
| 288 | self.__cond.release() |
| 289 | |
| 290 | def clear(self): |
| 291 | self.__cond.acquire() |
| 292 | self.__flag = 0 |
| 293 | self.__cond.release() |
| 294 | |
| 295 | def wait(self, timeout=None): |
| 296 | self.__cond.acquire() |
| 297 | if not self.__flag: |
| 298 | self.__cond.wait(timeout) |
| 299 | self.__cond.release() |
| 300 | |
| 301 | |
| 302 | # Helper to generate new thread names |
| 303 | _counter = 0 |
| 304 | def _newname(template="Thread-%d"): |
| 305 | global _counter |
| 306 | _counter = _counter + 1 |
| 307 | return template % _counter |
| 308 | |
| 309 | # Active thread administration |
| 310 | _active_limbo_lock = _allocate_lock() |
| 311 | _active = {} |
| 312 | _limbo = {} |
| 313 | |
| 314 | |
| 315 | # Main class for threads |
| 316 | |
| 317 | class Thread(_Verbose): |
| 318 | |
| 319 | __initialized = 0 |
| 320 | |
| 321 | def __init__(self, group=None, target=None, name=None, |
| 322 | args=(), kwargs={}, verbose=None): |
| 323 | assert group is None, "group argument must be None for now" |
| 324 | _Verbose.__init__(self, verbose) |
| 325 | self.__target = target |
| 326 | self.__name = str(name or _newname()) |
| 327 | self.__args = args |
| 328 | self.__kwargs = kwargs |
| 329 | self.__daemonic = self._set_daemon() |
| 330 | self.__started = 0 |
| 331 | self.__stopped = 0 |
| 332 | self.__block = Condition(Lock()) |
| 333 | self.__initialized = 1 |
| 334 | |
| 335 | def _set_daemon(self): |
| 336 | # Overridden in _MainThread and _DummyThread |
| 337 | return currentThread().isDaemon() |
| 338 | |
| 339 | def __repr__(self): |
| 340 | assert self.__initialized, "Thread.__init__() was not called" |
| 341 | status = "initial" |
| 342 | if self.__started: |
| 343 | status = "started" |
| 344 | if self.__stopped: |
| 345 | status = "stopped" |
| 346 | if self.__daemonic: |
| 347 | status = status + " daemon" |
| 348 | return "<%s(%s, %s)>" % (self.__class__.__name__, self.__name, status) |
| 349 | |
| 350 | def start(self): |
| 351 | assert self.__initialized, "Thread.__init__() not called" |
| 352 | assert not self.__started, "thread already started" |
| 353 | if __debug__: |
| 354 | self._note("%s.start(): starting thread", self) |
| 355 | _active_limbo_lock.acquire() |
| 356 | _limbo[self] = self |
| 357 | _active_limbo_lock.release() |
| 358 | _start_new_thread(self.__bootstrap, ()) |
| 359 | self.__started = 1 |
| 360 | _sleep(0.000001) # 1 usec, to let the thread run (Solaris hack) |
| 361 | |
| 362 | def run(self): |
| 363 | if self.__target: |
| 364 | apply(self.__target, self.__args, self.__kwargs) |
| 365 | |
| 366 | def __bootstrap(self): |
| 367 | try: |
| 368 | self.__started = 1 |
| 369 | _active_limbo_lock.acquire() |
| 370 | _active[_get_ident()] = self |
| 371 | del _limbo[self] |
| 372 | _active_limbo_lock.release() |
| 373 | if __debug__: |
| 374 | self._note("%s.__bootstrap(): thread started", self) |
| 375 | try: |
| 376 | self.run() |
| 377 | except SystemExit: |
| 378 | if __debug__: |
| 379 | self._note("%s.__bootstrap(): raised SystemExit", self) |
| 380 | except: |
| 381 | if __debug__: |
| 382 | self._note("%s.__bootstrap(): unhandled exception", self) |
| 383 | s = _StringIO() |
| 384 | _print_exc(file=s) |
| 385 | _sys.stderr.write("Exception in thread %s:\n%s\n" % |
| 386 | (self.getName(), s.getvalue())) |
| 387 | else: |
| 388 | if __debug__: |
| 389 | self._note("%s.__bootstrap(): normal return", self) |
| 390 | finally: |
| 391 | self.__stop() |
| 392 | self.__delete() |
| 393 | |
| 394 | def __stop(self): |
| 395 | self.__block.acquire() |
| 396 | self.__stopped = 1 |
| 397 | self.__block.notifyAll() |
| 398 | self.__block.release() |
| 399 | |
| 400 | def __delete(self): |
| 401 | _active_limbo_lock.acquire() |
| 402 | del _active[_get_ident()] |
| 403 | _active_limbo_lock.release() |
| 404 | |
| 405 | def join(self, timeout=None): |
| 406 | assert self.__initialized, "Thread.__init__() not called" |
| 407 | assert self.__started, "cannot join thread before it is started" |
| 408 | assert self is not currentThread(), "cannot join current thread" |
| 409 | if __debug__: |
| 410 | if not self.__stopped: |
| 411 | self._note("%s.join(): waiting until thread stops", self) |
| 412 | self.__block.acquire() |
| 413 | if timeout is None: |
| 414 | while not self.__stopped: |
| 415 | self.__block.wait() |
| 416 | if __debug__: |
| 417 | self._note("%s.join(): thread stopped", self) |
| 418 | else: |
| 419 | deadline = time.time() + timeout |
| 420 | while not self.__stopped: |
| 421 | delay = deadline - time.time() |
| 422 | if delay <= 0: |
| 423 | if __debug__: |
| 424 | self._note("%s.join(): timed out", self) |
| 425 | break |
| 426 | self.__block.wait(delay) |
| 427 | else: |
| 428 | if __debug__: |
| 429 | self._note("%s.join(): thread stopped", self) |
| 430 | self.__block.release() |
| 431 | |
| 432 | def getName(self): |
| 433 | assert self.__initialized, "Thread.__init__() not called" |
| 434 | return self.__name |
| 435 | |
| 436 | def setName(self, name): |
| 437 | assert self.__initialized, "Thread.__init__() not called" |
| 438 | self.__name = str(name) |
| 439 | |
| 440 | def isAlive(self): |
| 441 | assert self.__initialized, "Thread.__init__() not called" |
| 442 | return self.__started and not self.__stopped |
| 443 | |
| 444 | def isDaemon(self): |
| 445 | assert self.__initialized, "Thread.__init__() not called" |
| 446 | return self.__daemonic |
| 447 | |
| 448 | def setDaemon(self, daemonic): |
| 449 | assert self.__initialized, "Thread.__init__() not called" |
| 450 | assert not self.__started, "cannot set daemon status of active thread" |
| 451 | self.__daemonic = daemonic |
| 452 | |
| 453 | |
| 454 | # Special thread class to represent the main thread |
| 455 | # This is garbage collected through an exit handler |
| 456 | |
| 457 | class _MainThread(Thread): |
| 458 | |
| 459 | def __init__(self): |
| 460 | Thread.__init__(self, name="MainThread") |
| 461 | self._Thread__started = 1 |
| 462 | _active_limbo_lock.acquire() |
| 463 | _active[_get_ident()] = self |
| 464 | _active_limbo_lock.release() |
| 465 | try: |
| 466 | self.__oldexitfunc = _sys.exitfunc |
| 467 | except AttributeError: |
| 468 | self.__oldexitfunc = None |
| 469 | _sys.exitfunc = self.__exitfunc |
| 470 | |
| 471 | def _set_daemon(self): |
| 472 | return 0 |
| 473 | |
| 474 | def __exitfunc(self): |
| 475 | self._Thread__stop() |
| 476 | t = _pickSomeNonDaemonThread() |
| 477 | if t: |
| 478 | if __debug__: |
| 479 | self._note("%s: waiting for other threads", self) |
| 480 | while t: |
| 481 | t.join() |
| 482 | t = _pickSomeNonDaemonThread() |
| 483 | if self.__oldexitfunc: |
| 484 | if __debug__: |
| 485 | self._note("%s: calling exit handler", self) |
| 486 | self.__oldexitfunc() |
| 487 | if __debug__: |
| 488 | self._note("%s: exiting", self) |
| 489 | self._Thread__delete() |
| 490 | |
| 491 | def _pickSomeNonDaemonThread(): |
| 492 | for t in enumerate(): |
| 493 | if not t.isDaemon() and t.isAlive(): |
| 494 | return t |
| 495 | return None |
| 496 | |
| 497 | |
| 498 | # Dummy thread class to represent threads not started here. |
| 499 | # These aren't garbage collected when they die, |
| 500 | # nor can they be waited for. |
| 501 | # Their purpose is to return *something* from currentThread(). |
| 502 | # They are marked as daemon threads so we won't wait for them |
| 503 | # when we exit (conform previous semantics). |
| 504 | |
| 505 | class _DummyThread(Thread): |
| 506 | |
| 507 | def __init__(self): |
| 508 | Thread.__init__(self, name=_newname("Dummy-%d")) |
| 509 | self.__Thread_started = 1 |
| 510 | _active_limbo_lock.acquire() |
| 511 | _active[_get_ident()] = self |
| 512 | _active_limbo_lock.release() |
| 513 | |
| 514 | def _set_daemon(self): |
| 515 | return 1 |
| 516 | |
| 517 | def join(self): |
| 518 | assert 0, "cannot join a dummy thread" |
| 519 | |
| 520 | |
| 521 | # Global API functions |
| 522 | |
| 523 | def currentThread(): |
| 524 | try: |
| 525 | return _active[_get_ident()] |
| 526 | except KeyError: |
| 527 | print "currentThread(): no current thread for", _get_ident() |
| 528 | return _DummyThread() |
| 529 | |
| 530 | def activeCount(): |
| 531 | _active_limbo_lock.acquire() |
| 532 | count = len(_active) + len(_limbo) |
| 533 | _active_limbo_lock.release() |
| 534 | return count |
| 535 | |
| 536 | def enumerate(): |
| 537 | _active_limbo_lock.acquire() |
| 538 | active = _active.values() + _limbo.values() |
| 539 | _active_limbo_lock.release() |
| 540 | return active |
| 541 | |
| 542 | |
| 543 | # Create the main thread object |
| 544 | |
| 545 | _MainThread() |
| 546 | |
| 547 | |
| 548 | # Self-test code |
| 549 | |
| 550 | def _test(): |
| 551 | |
| 552 | import whrandom |
| 553 | |
| 554 | class BoundedQueue(_Verbose): |
| 555 | |
| 556 | def __init__(self, limit): |
| 557 | _Verbose.__init__(self) |
| 558 | self.mon = RLock() |
| 559 | self.rc = Condition(self.mon) |
| 560 | self.wc = Condition(self.mon) |
| 561 | self.limit = limit |
| 562 | self.queue = [] |
| 563 | |
| 564 | def put(self, item): |
| 565 | self.mon.acquire() |
| 566 | while len(self.queue) >= self.limit: |
| 567 | self._note("put(%s): queue full", item) |
| 568 | self.wc.wait() |
| 569 | self.queue.append(item) |
| 570 | self._note("put(%s): appended, length now %d", |
| 571 | item, len(self.queue)) |
| 572 | self.rc.notify() |
| 573 | self.mon.release() |
| 574 | |
| 575 | def get(self): |
| 576 | self.mon.acquire() |
| 577 | while not self.queue: |
| 578 | self._note("get(): queue empty") |
| 579 | self.rc.wait() |
| 580 | item = self.queue[0] |
| 581 | del self.queue[0] |
| 582 | self._note("get(): got %s, %d left", item, len(self.queue)) |
| 583 | self.wc.notify() |
| 584 | self.mon.release() |
| 585 | return item |
| 586 | |
| 587 | class ProducerThread(Thread): |
| 588 | |
| 589 | def __init__(self, queue, quota): |
| 590 | Thread.__init__(self, name="Producer") |
| 591 | self.queue = queue |
| 592 | self.quota = quota |
| 593 | |
| 594 | def run(self): |
| 595 | from whrandom import random |
| 596 | counter = 0 |
| 597 | while counter < self.quota: |
| 598 | counter = counter + 1 |
| 599 | self.queue.put("%s.%d" % (self.getName(), counter)) |
| 600 | _sleep(random() * 0.00001) |
| 601 | |
| 602 | |
| 603 | class ConsumerThread(Thread): |
| 604 | |
| 605 | def __init__(self, queue, count): |
| 606 | Thread.__init__(self, name="Consumer") |
| 607 | self.queue = queue |
| 608 | self.count = count |
| 609 | |
| 610 | def run(self): |
| 611 | while self.count > 0: |
| 612 | item = self.queue.get() |
| 613 | print item |
| 614 | self.count = self.count - 1 |
| 615 | |
| 616 | import time |
| 617 | |
| 618 | NP = 3 |
| 619 | QL = 4 |
| 620 | NI = 5 |
| 621 | |
| 622 | Q = BoundedQueue(QL) |
| 623 | P = [] |
| 624 | for i in range(NP): |
| 625 | t = ProducerThread(Q, NI) |
| 626 | t.setName("Producer-%d" % (i+1)) |
| 627 | P.append(t) |
| 628 | C = ConsumerThread(Q, NI*NP) |
| 629 | for t in P: |
| 630 | t.start() |
| 631 | _sleep(0.000001) |
| 632 | C.start() |
| 633 | for t in P: |
| 634 | t.join() |
| 635 | C.join() |
| 636 | |
| 637 | if __name__ == '__main__': |
| 638 | _test() |