add the multiprocessing package to fulfill PEP 371

Doc/includes/mp_benchmarks.py

+#
+# Simple benchmarks for the multiprocessing package
+#
+
+import time, sys, multiprocessing, threading, Queue, gc
+
+if sys.platform == 'win32':
+    _timer = time.clock
+else:
+    _timer = time.time
+
+delta = 1
+
+
+#### TEST_QUEUESPEED
+
+def queuespeed_func(q, c, iterations):
+    a = '0' * 256
+    c.acquire()
+    c.notify()
+    c.release()
+
+    for i in xrange(iterations):
+        q.put(a)
+
+    q.put('STOP')
+
+def test_queuespeed(Process, q, c):
+    elapsed = 0
+    iterations = 1
+
+    while elapsed < delta:
+        iterations *= 2
+
+        p = Process(target=queuespeed_func, args=(q, c, iterations))
+        c.acquire()
+        p.start()
+        c.wait()
+        c.release()
+
+        result = None
+        t = _timer()
+
+        while result != 'STOP':
+            result = q.get()
+
+        elapsed = _timer() - t
+
+        p.join()
+
+    print iterations, 'objects passed through the queue in', elapsed, 'seconds'
+    print 'average number/sec:', iterations/elapsed
+
+
+#### TEST_PIPESPEED
+
+def pipe_func(c, cond, iterations):
+    a = '0' * 256
+    cond.acquire()
+    cond.notify()
+    cond.release()
+
+    for i in xrange(iterations):
+        c.send(a)
+
+    c.send('STOP')
+
+def test_pipespeed():
+    c, d = multiprocessing.Pipe()
+    cond = multiprocessing.Condition()
+    elapsed = 0
+    iterations = 1
+
+    while elapsed < delta:
+        iterations *= 2
+
+        p = multiprocessing.Process(target=pipe_func,
+                                    args=(d, cond, iterations))
+        cond.acquire()
+        p.start()
+        cond.wait()
+        cond.release()
+
+        result = None
+        t = _timer()
+
+        while result != 'STOP':
+            result = c.recv()
+
+        elapsed = _timer() - t
+        p.join()
+
+    print iterations, 'objects passed through connection in',elapsed,'seconds'
+    print 'average number/sec:', iterations/elapsed
+
+
+#### TEST_SEQSPEED
+
+def test_seqspeed(seq):
+    elapsed = 0
+    iterations = 1
+
+    while elapsed < delta:
+        iterations *= 2
+
+        t = _timer()
+
+        for i in xrange(iterations):
+            a = seq[5]
+
+        elapsed = _timer()-t
+
+    print iterations, 'iterations in', elapsed, 'seconds'
+    print 'average number/sec:', iterations/elapsed
+
+
+#### TEST_LOCK
+
+def test_lockspeed(l):
+    elapsed = 0
+    iterations = 1
+
+    while elapsed < delta:
+        iterations *= 2
+
+        t = _timer()
+
+        for i in xrange(iterations):
+            l.acquire()
+            l.release()
+
+        elapsed = _timer()-t
+
+    print iterations, 'iterations in', elapsed, 'seconds'
+    print 'average number/sec:', iterations/elapsed
+
+
+#### TEST_CONDITION
+
+def conditionspeed_func(c, N):
+    c.acquire()
+    c.notify()
+
+    for i in xrange(N):
+        c.wait()
+        c.notify()
+
+    c.release()
+
+def test_conditionspeed(Process, c):
+    elapsed = 0
+    iterations = 1
+
+    while elapsed < delta:
+        iterations *= 2
+
+        c.acquire()
+        p = Process(target=conditionspeed_func, args=(c, iterations))
+        p.start()
+
+        c.wait()
+
+        t = _timer()
+
+        for i in xrange(iterations):
+            c.notify()
+            c.wait()
+
+        elapsed = _timer()-t
+
+        c.release()
+        p.join()
+
+    print iterations * 2, 'waits in', elapsed, 'seconds'
+    print 'average number/sec:', iterations * 2 / elapsed
+
+####
+
+def test():
+    manager = multiprocessing.Manager()
+
+    gc.disable()
+
+    print '\n\t######## testing Queue.Queue\n'
+    test_queuespeed(threading.Thread, Queue.Queue(),
+                    threading.Condition())
+    print '\n\t######## testing multiprocessing.Queue\n'
+    test_queuespeed(multiprocessing.Process, multiprocessing.Queue(),
+                    multiprocessing.Condition())
+    print '\n\t######## testing Queue managed by server process\n'
+    test_queuespeed(multiprocessing.Process, manager.Queue(),
+                    manager.Condition())
+    print '\n\t######## testing multiprocessing.Pipe\n'
+    test_pipespeed()
+
+    print
+
+    print '\n\t######## testing list\n'
+    test_seqspeed(range(10))
+    print '\n\t######## testing list managed by server process\n'
+    test_seqspeed(manager.list(range(10)))
+    print '\n\t######## testing Array("i", ..., lock=False)\n'
+    test_seqspeed(multiprocessing.Array('i', range(10), lock=False))
+    print '\n\t######## testing Array("i", ..., lock=True)\n'
+    test_seqspeed(multiprocessing.Array('i', range(10), lock=True))
+
+    print
+
+    print '\n\t######## testing threading.Lock\n'
+    test_lockspeed(threading.Lock())
+    print '\n\t######## testing threading.RLock\n'
+    test_lockspeed(threading.RLock())
+    print '\n\t######## testing multiprocessing.Lock\n'
+    test_lockspeed(multiprocessing.Lock())
+    print '\n\t######## testing multiprocessing.RLock\n'
+    test_lockspeed(multiprocessing.RLock())
+    print '\n\t######## testing lock managed by server process\n'
+    test_lockspeed(manager.Lock())
+    print '\n\t######## testing rlock managed by server process\n'
+    test_lockspeed(manager.RLock())
+
+    print
+
+    print '\n\t######## testing threading.Condition\n'
+    test_conditionspeed(threading.Thread, threading.Condition())
+    print '\n\t######## testing multiprocessing.Condition\n'
+    test_conditionspeed(multiprocessing.Process, multiprocessing.Condition())
+    print '\n\t######## testing condition managed by a server process\n'
+    test_conditionspeed(multiprocessing.Process, manager.Condition())
+
+    gc.enable()
+
+if __name__ == '__main__':
+    multiprocessing.freeze_support()
+    test()

Doc/includes/mp_newtype.py

+#
+# This module shows how to use arbitrary callables with a subclass of
+# `BaseManager`.
+#
+
+from multiprocessing import freeze_support
+from multiprocessing.managers import BaseManager, BaseProxy
+import operator
+
+##
+
+class Foo(object):
+    def f(self):
+        print 'you called Foo.f()'
+    def g(self):
+        print 'you called Foo.g()'
+    def _h(self):
+        print 'you called Foo._h()'
+
+# A simple generator function
+def baz():
+    for i in xrange(10):
+        yield i*i
+
+# Proxy type for generator objects
+class GeneratorProxy(BaseProxy):
+    _exposed_ = ('next', '__next__')
+    def __iter__(self):
+        return self
+    def next(self):
+        return self._callmethod('next')
+    def __next__(self):
+        return self._callmethod('__next__')
+
+# Function to return the operator module
+def get_operator_module():
+    return operator
+
+##
+
+class MyManager(BaseManager):
+    pass
+
+# register the Foo class; make `f()` and `g()` accessible via proxy
+MyManager.register('Foo1', Foo)
+
+# register the Foo class; make `g()` and `_h()` accessible via proxy
+MyManager.register('Foo2', Foo, exposed=('g', '_h'))
+
+# register the generator function baz; use `GeneratorProxy` to make proxies
+MyManager.register('baz', baz, proxytype=GeneratorProxy)
+
+# register get_operator_module(); make public functions accessible via proxy
+MyManager.register('operator', get_operator_module)
+
+##
+
+def test():
+    manager = MyManager()
+    manager.start()
+
+    print '-' * 20
+
+    f1 = manager.Foo1()
+    f1.f()
+    f1.g()
+    assert not hasattr(f1, '_h')
+    assert sorted(f1._exposed_) == sorted(['f', 'g'])
+
+    print '-' * 20
+
+    f2 = manager.Foo2()
+    f2.g()
+    f2._h()
+    assert not hasattr(f2, 'f')
+    assert sorted(f2._exposed_) == sorted(['g', '_h'])
+
+    print '-' * 20
+
+    it = manager.baz()
+    for i in it:
+        print '<%d>' % i,
+    print
+
+    print '-' * 20
+
+    op = manager.operator()
+    print 'op.add(23, 45) =', op.add(23, 45)
+    print 'op.pow(2, 94) =', op.pow(2, 94)
+    print 'op.getslice(range(10), 2, 6) =', op.getslice(range(10), 2, 6)
+    print 'op.repeat(range(5), 3) =', op.repeat(range(5), 3)
+    print 'op._exposed_ =', op._exposed_
+
+##
+
+if __name__ == '__main__':
+    freeze_support()
+    test()

Doc/includes/mp_pool.py

+#
+# A test of `multiprocessing.Pool` class
+#
+
+import multiprocessing
+import time
+import random
+import sys
+
+#
+# Functions used by test code
+#
+
+def calculate(func, args):
+    result = func(*args)
+    return '%s says that %s%s = %s' % (
+        multiprocessing.current_process().get_name(),
+        func.__name__, args, result
+        )
+
+def calculatestar(args):
+    return calculate(*args)
+
+def mul(a, b):
+    time.sleep(0.5*random.random())
+    return a * b
+
+def plus(a, b):
+    time.sleep(0.5*random.random())
+    return a + b
+
+def f(x):
+    return 1.0 / (x-5.0)
+
+def pow3(x):
+    return x**3
+
+def noop(x):
+    pass
+
+#
+# Test code
+#
+
+def test():
+    print 'cpu_count() = %d\n' % multiprocessing.cpu_count()
+
+    #
+    # Create pool
+    #
+
+    PROCESSES = 4
+    print 'Creating pool with %d processes\n' % PROCESSES
+    pool = multiprocessing.Pool(PROCESSES)
+    print 'pool = %s' % pool
+    print
+
+    #
+    # Tests
+    #
+
+    TASKS = [(mul, (i, 7)) for i in range(10)] + \
+            [(plus, (i, 8)) for i in range(10)]
+
+    results = [pool.apply_async(calculate, t) for t in TASKS]
+    imap_it = pool.imap(calculatestar, TASKS)
+    imap_unordered_it = pool.imap_unordered(calculatestar, TASKS)
+
+    print 'Ordered results using pool.apply_async():'
+    for r in results:
+        print '\t', r.get()
+    print
+
+    print 'Ordered results using pool.imap():'
+    for x in imap_it:
+        print '\t', x
+    print
+
+    print 'Unordered results using pool.imap_unordered():'
+    for x in imap_unordered_it:
+        print '\t', x
+    print
+
+    print 'Ordered results using pool.map() --- will block till complete:'
+    for x in pool.map(calculatestar, TASKS):
+        print '\t', x
+    print
+
+    #
+    # Simple benchmarks
+    #
+
+    N = 100000
+    print 'def pow3(x): return x**3'
+
+    t = time.time()
+    A = map(pow3, xrange(N))
+    print '\tmap(pow3, xrange(%d)):\n\t\t%s seconds' % \
+          (N, time.time() - t)
+
+    t = time.time()
+    B = pool.map(pow3, xrange(N))
+    print '\tpool.map(pow3, xrange(%d)):\n\t\t%s seconds' % \
+          (N, time.time() - t)
+
+    t = time.time()
+    C = list(pool.imap(pow3, xrange(N), chunksize=N//8))
+    print '\tlist(pool.imap(pow3, xrange(%d), chunksize=%d)):\n\t\t%s' \
+          ' seconds' % (N, N//8, time.time() - t)
+
+    assert A == B == C, (len(A), len(B), len(C))
+    print
+
+    L = [None] * 1000000
+    print 'def noop(x): pass'
+    print 'L = [None] * 1000000'
+
+    t = time.time()
+    A = map(noop, L)
+    print '\tmap(noop, L):\n\t\t%s seconds' % \
+          (time.time() - t)
+
+    t = time.time()
+    B = pool.map(noop, L)
+    print '\tpool.map(noop, L):\n\t\t%s seconds' % \
+          (time.time() - t)
+
+    t = time.time()
+    C = list(pool.imap(noop, L, chunksize=len(L)//8))
+    print '\tlist(pool.imap(noop, L, chunksize=%d)):\n\t\t%s seconds' % \
+          (len(L)//8, time.time() - t)
+
+    assert A == B == C, (len(A), len(B), len(C))
+    print
+
+    del A, B, C, L
+
+    #
+    # Test error handling
+    #
+
+    print 'Testing error handling:'
+
+    try:
+        print pool.apply(f, (5,))
+    except ZeroDivisionError:
+        print '\tGot ZeroDivisionError as expected from pool.apply()'
+    else:
+        raise AssertionError, 'expected ZeroDivisionError'
+
+    try:
+        print pool.map(f, range(10))
+    except ZeroDivisionError:
+        print '\tGot ZeroDivisionError as expected from pool.map()'
+    else:
+        raise AssertionError, 'expected ZeroDivisionError'
+
+    try:
+        print list(pool.imap(f, range(10)))
+    except ZeroDivisionError:
+        print '\tGot ZeroDivisionError as expected from list(pool.imap())'
+    else:
+        raise AssertionError, 'expected ZeroDivisionError'
+
+    it = pool.imap(f, range(10))
+    for i in range(10):
+        try:
+            x = it.next()
+        except ZeroDivisionError:
+            if i == 5:
+                pass
+        except StopIteration:
+            break
+        else:
+            if i == 5:
+                raise AssertionError, 'expected ZeroDivisionError'
+
+    assert i == 9
+    print '\tGot ZeroDivisionError as expected from IMapIterator.next()'
+    print
+
+    #
+    # Testing timeouts
+    #
+
+    print 'Testing ApplyResult.get() with timeout:',
+    res = pool.apply_async(calculate, TASKS[0])
+    while 1:
+        sys.stdout.flush()
+        try:
+            sys.stdout.write('\n\t%s' % res.get(0.02))
+            break
+        except multiprocessing.TimeoutError:
+            sys.stdout.write('.')
+    print
+    print
+
+    print 'Testing IMapIterator.next() with timeout:',
+    it = pool.imap(calculatestar, TASKS)
+    while 1:
+        sys.stdout.flush()
+        try:
+            sys.stdout.write('\n\t%s' % it.next(0.02))
+        except StopIteration:
+            break
+        except multiprocessing.TimeoutError:
+            sys.stdout.write('.')
+    print
+    print
+
+    #
+    # Testing callback
+    #
+
+    print 'Testing callback:'
+
+    A = []
+    B = [56, 0, 1, 8, 27, 64, 125, 216, 343, 512, 729]
+
+    r = pool.apply_async(mul, (7, 8), callback=A.append)
+    r.wait()
+
+    r = pool.map_async(pow3, range(10), callback=A.extend)
+    r.wait()
+
+    if A == B:
+        print '\tcallbacks succeeded\n'
+    else:
+        print '\t*** callbacks failed\n\t\t%s != %s\n' % (A, B)
+
+    #
+    # Check there are no outstanding tasks
+    #
+
+    assert not pool._cache, 'cache = %r' % pool._cache
+
+    #
+    # Check close() methods
+    #
+
+    print 'Testing close():'
+
+    for worker in pool._pool:
+        assert worker.is_alive()
+
+    result = pool.apply_async(time.sleep, [0.5])
+    pool.close()
+    pool.join()
+
+    assert result.get() is None
+
+    for worker in pool._pool:
+        assert not worker.is_alive()
+
+    print '\tclose() succeeded\n'
+
+    #
+    # Check terminate() method
+    #
+
+    print 'Testing terminate():'
+
+    pool = multiprocessing.Pool(2)
+    DELTA = 0.1
+    ignore = pool.apply(pow3, [2])
+    results = [pool.apply_async(time.sleep, [DELTA]) for i in range(100)]
+    pool.terminate()
+    pool.join()
+
+    for worker in pool._pool:
+        assert not worker.is_alive()
+
+    print '\tterminate() succeeded\n'
+
+    #
+    # Check garbage collection
+    #
+
+    print 'Testing garbage collection:'
+
+    pool = multiprocessing.Pool(2)
+    DELTA = 0.1
+    processes = pool._pool
+    ignore = pool.apply(pow3, [2])
+    results = [pool.apply_async(time.sleep, [DELTA]) for i in range(100)]
+
+    results = pool = None
+
+    time.sleep(DELTA * 2)
+
+    for worker in processes:
+        assert not worker.is_alive()
+
+    print '\tgarbage collection succeeded\n'
+
+
+if __name__ == '__main__':
+    multiprocessing.freeze_support()
+
+    assert len(sys.argv) in (1, 2)
+
+    if len(sys.argv) == 1 or sys.argv[1] == 'processes':
+        print ' Using processes '.center(79, '-')
+    elif sys.argv[1] == 'threads':
+        print ' Using threads '.center(79, '-')
+        import multiprocessing.dummy as multiprocessing
+    else:
+        print 'Usage:\n\t%s [processes | threads]' % sys.argv[0]
+        raise SystemExit(2)
+
+    test()

Doc/includes/mp_synchronize.py

+#
+# A test file for the `multiprocessing` package
+#
+
+import time, sys, random
+from Queue import Empty
+
+import multiprocessing               # may get overwritten
+
+
+#### TEST_VALUE
+
+def value_func(running, mutex):
+    random.seed()
+    time.sleep(random.random()*4)
+
+    mutex.acquire()
+    print '\n\t\t\t' + str(multiprocessing.current_process()) + ' has finished'
+    running.value -= 1
+    mutex.release()
+
+def test_value():
+    TASKS = 10
+    running = multiprocessing.Value('i', TASKS)
+    mutex = multiprocessing.Lock()
+
+    for i in range(TASKS):
+        p = multiprocessing.Process(target=value_func, args=(running, mutex))
+        p.start()
+
+    while running.value > 0:
+        time.sleep(0.08)
+        mutex.acquire()
+        print running.value,
+        sys.stdout.flush()
+        mutex.release()
+
+    print
+    print 'No more running processes'
+
+
+#### TEST_QUEUE
+
+def queue_func(queue):
+    for i in range(30):
+        time.sleep(0.5 * random.random())
+        queue.put(i*i)
+    queue.put('STOP')
+
+def test_queue():
+    q = multiprocessing.Queue()
+
+    p = multiprocessing.Process(target=queue_func, args=(q,))
+    p.start()
+
+    o = None
+    while o != 'STOP':
+        try:
+            o = q.get(timeout=0.3)
+            print o,
+            sys.stdout.flush()
+        except Empty:
+            print 'TIMEOUT'
+
+    print
+
+
+#### TEST_CONDITION
+
+def condition_func(cond):
+    cond.acquire()
+    print '\t' + str(cond)
+    time.sleep(2)
+    print '\tchild is notifying'
+    print '\t' + str(cond)
+    cond.notify()
+    cond.release()
+
+def test_condition():
+    cond = multiprocessing.Condition()
+
+    p = multiprocessing.Process(target=condition_func, args=(cond,))
+    print cond
+
+    cond.acquire()
+    print cond
+    cond.acquire()
+    print cond
+
+    p.start()
+
+    print 'main is waiting'
+    cond.wait()
+    print 'main has woken up'
+
+    print cond
+    cond.release()
+    print cond
+    cond.release()
+
+    p.join()
+    print cond
+
+
+#### TEST_SEMAPHORE
+
+def semaphore_func(sema, mutex, running):
+    sema.acquire()
+
+    mutex.acquire()
+    running.value += 1
+    print running.value, 'tasks are running'
+    mutex.release()
+
+    random.seed()
+    time.sleep(random.random()*2)
+
+    mutex.acquire()
+    running.value -= 1
+    print '%s has finished' % multiprocessing.current_process()
+    mutex.release()
+
+    sema.release()
+
+def test_semaphore():
+    sema = multiprocessing.Semaphore(3)
+    mutex = multiprocessing.RLock()
+    running = multiprocessing.Value('i', 0)
+
+    processes = [
+        multiprocessing.Process(target=semaphore_func,
+                                args=(sema, mutex, running))
+        for i in range(10)
+        ]
+
+    for p in processes:
+        p.start()
+
+    for p in processes:
+        p.join()
+
+
+#### TEST_JOIN_TIMEOUT
+
+def join_timeout_func():
+    print '\tchild sleeping'
+    time.sleep(5.5)
+    print '\n\tchild terminating'
+
+def test_join_timeout():
+    p = multiprocessing.Process(target=join_timeout_func)
+    p.start()
+
+    print 'waiting for process to finish'
+
+    while 1:
+        p.join(timeout=1)
+        if not p.is_alive():
+            break
+        print '.',
+        sys.stdout.flush()
+
+
+#### TEST_EVENT
+
+def event_func(event):
+    print '\t%r is waiting' % multiprocessing.current_process()
+    event.wait()
+    print '\t%r has woken up' % multiprocessing.current_process()
+
+def test_event():
+    event = multiprocessing.Event()
+
+    processes = [multiprocessing.Process(target=event_func, args=(event,))
+                 for i in range(5)]
+
+    for p in processes:
+        p.start()
+
+    print 'main is sleeping'
+    time.sleep(2)
+
+    print 'main is setting event'
+    event.set()
+
+    for p in processes:
+        p.join()
+
+
+#### TEST_SHAREDVALUES
+
+def sharedvalues_func(values, arrays, shared_values, shared_arrays):
+    for i in range(len(values)):
+        v = values[i][1]
+        sv = shared_values[i].value
+        assert v == sv
+
+    for i in range(len(values)):
+        a = arrays[i][1]
+        sa = list(shared_arrays[i][:])
+        assert a == sa
+
+    print 'Tests passed'
+
+def test_sharedvalues():
+    values = [
+        ('i', 10),
+        ('h', -2),
+        ('d', 1.25)
+        ]
+    arrays = [
+        ('i', range(100)),
+        ('d', [0.25 * i for i in range(100)]),
+        ('H', range(1000))
+        ]
+
+    shared_values = [multiprocessing.Value(id, v) for id, v in values]
+    shared_arrays = [multiprocessing.Array(id, a) for id, a in arrays]
+
+    p = multiprocessing.Process(
+        target=sharedvalues_func,
+        args=(values, arrays, shared_values, shared_arrays)
+        )
+    p.start()
+    p.join()
+
+    assert p.get_exitcode() == 0
+
+
+####
+
+def test(namespace=multiprocessing):
+    global multiprocessing
+
+    multiprocessing = namespace
+
+    for func in [ test_value, test_queue, test_condition,
+                  test_semaphore, test_join_timeout, test_event,
+                  test_sharedvalues ]:
+
+        print '\n\t######## %s\n' % func.__name__
+        func()
+
+    ignore = multiprocessing.active_children()      # cleanup any old processes
+    if hasattr(multiprocessing, '_debug_info'):
+        info = multiprocessing._debug_info()
+        if info:
+            print info
+            raise ValueError, 'there should be no positive refcounts left'
+
+
+if __name__ == '__main__':
+    multiprocessing.freeze_support()
+
+    assert len(sys.argv) in (1, 2)
+
+    if len(sys.argv) == 1 or sys.argv[1] == 'processes':
+        print ' Using processes '.center(79, '-')
+        namespace = multiprocessing
+    elif sys.argv[1] == 'manager':
+        print ' Using processes and a manager '.center(79, '-')
+        namespace = multiprocessing.Manager()
+        namespace.Process = multiprocessing.Process
+        namespace.current_process = multiprocessing.current_process
+        namespace.active_children = multiprocessing.active_children
+    elif sys.argv[1] == 'threads':
+        print ' Using threads '.center(79, '-')
+        import multiprocessing.dummy as namespace
+    else:
+        print 'Usage:\n\t%s [processes | manager | threads]' % sys.argv[0]
+        raise SystemExit, 2
+
+    test(namespace)

Doc/includes/mp_webserver.py

+#
+# Example where a pool of http servers share a single listening socket
+#
+# On Windows this module depends on the ability to pickle a socket
+# object so that the worker processes can inherit a copy of the server
+# object.  (We import `multiprocessing.reduction` to enable this pickling.)
+#
+# Not sure if we should synchronize access to `socket.accept()` method by
+# using a process-shared lock -- does not seem to be necessary.
+#
+
+import os
+import sys
+
+from multiprocessing import Process, current_process, freeze_support
+from BaseHTTPServer import HTTPServer
+from SimpleHTTPServer import SimpleHTTPRequestHandler
+
+if sys.platform == 'win32':
+    import multiprocessing.reduction    # make sockets pickable/inheritable
+
+
+def note(format, *args):
+    sys.stderr.write('[%s]\t%s\n' % (current_process().get_name(),format%args))
+
+
+class RequestHandler(SimpleHTTPRequestHandler):
+    # we override log_message() to show which process is handling the request
+    def log_message(self, format, *args):
+        note(format, *args)
+
+def serve_forever(server):
+    note('starting server')
+    try:
+        server.serve_forever()
+    except KeyboardInterrupt:
+        pass
+
+
+def runpool(address, number_of_processes):
+    # create a single server object -- children will each inherit a copy
+    server = HTTPServer(address, RequestHandler)
+
+    # create child processes to act as workers
+    for i in range(number_of_processes-1):
+        Process(target=serve_forever, args=(server,)).start()
+
+    # main process also acts as a worker
+    serve_forever(server)
+
+
+def test():
+    DIR = os.path.join(os.path.dirname(__file__), '..')
+    ADDRESS = ('localhost', 8000)
+    NUMBER_OF_PROCESSES = 4
+
+    print 'Serving at http://%s:%d using %d worker processes' % \
+          (ADDRESS[0], ADDRESS[1], NUMBER_OF_PROCESSES)
+    print 'To exit press Ctrl-' + ['C', 'Break'][sys.platform=='win32']
+
+    os.chdir(DIR)
+    runpool(ADDRESS, NUMBER_OF_PROCESSES)
+
+
+if __name__ == '__main__':
+    freeze_support()
+    test()

Doc/includes/mp_workers.py

+#
+# Simple example which uses a pool of workers to carry out some tasks.
+#
+# Notice that the results will probably not come out of the output
+# queue in the same in the same order as the corresponding tasks were
+# put on the input queue.  If it is important to get the results back
+# in the original order then consider using `Pool.map()` or
+# `Pool.imap()` (which will save on the amount of code needed anyway).
+#
+
+import time
+import random
+
+from multiprocessing import Process, Queue, current_process, freeze_support
+
+#
+# Function run by worker processes
+#
+
+def worker(input, output):
+    for func, args in iter(input.get, 'STOP'):
+        result = calculate(func, args)
+        output.put(result)
+
+#
+# Function used to calculate result
+#
+
+def calculate(func, args):
+    result = func(*args)
+    return '%s says that %s%s = %s' % \
+        (current_process().get_name(), func.__name__, args, result)
+
+#
+# Functions referenced by tasks
+#
+
+def mul(a, b):
+    time.sleep(0.5*random.random())
+    return a * b
+
+def plus(a, b):
+    time.sleep(0.5*random.random())
+    return a + b
+
+#
+#
+#
+
+def test():
+    NUMBER_OF_PROCESSES = 4
+    TASKS1 = [(mul, (i, 7)) for i in range(20)]
+    TASKS2 = [(plus, (i, 8)) for i in range(10)]
+
+    # Create queues
+    task_queue = Queue()
+    done_queue = Queue()
+
+    # Submit tasks
+    for task in TASKS1:
+        task_queue.put(task)
+
+    # Start worker processes
+    for i in range(NUMBER_OF_PROCESSES):
+        Process(target=worker, args=(task_queue, done_queue)).start()
+
+    # Get and print results
+    print 'Unordered results:'
+    for i in range(len(TASKS1)):
+        print '\t', done_queue.get()
+
+    # Add more tasks using `put()`
+    for task in TASKS2:
+        task_queue.put(task)
+
+    # Get and print some more results
+    for i in range(len(TASKS2)):
+        print '\t', done_queue.get()
+
+    # Tell child processes to stop
+    for i in range(NUMBER_OF_PROCESSES):
+        task_queue.put('STOP')
+
+
+if __name__ == '__main__':
+    freeze_support()
+    test()

Doc/library/someos.rst

@@ -18,6 +18,7 @@ some other systems as well (e.g. Windows or NT).  Here's an overview:
    threading.rst
    dummy_thread.rst
    dummy_threading.rst
+   multiprocessing.rst
    mmap.rst
    readline.rst
    rlcompleter.rst

Lib/multiprocessing/__init__.py

+#
+# Package analogous to 'threading.py' but using processes
+#
+# multiprocessing/__init__.py
+#
+# This package is intended to duplicate the functionality (and much of
+# the API) of threading.py but uses processes instead of threads.  A
+# subpackage 'multiprocessing.dummy' has the same API but is a simple
+# wrapper for 'threading'.
+#
+# Try calling `multiprocessing.doc.main()` to read the html
+# documentation in in a webbrowser.
+#
+#
+# Copyright (c) 2006-2008, R Oudkerk
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+# 3. Neither the name of author nor the names of any contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+#
+
+__version__ = '0.70a1'
+
+__all__ = [
+    'Process', 'current_process', 'active_children', 'freeze_support',
+    'Manager', 'Pipe', 'cpu_count', 'log_to_stderr', 'get_logger',
+    'allow_connection_pickling', 'BufferTooShort', 'TimeoutError',
+    'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Condition',
+    'Event', 'Queue', 'JoinableQueue', 'Pool', 'Value', 'Array',
+    'RawValue', 'RawArray'
+    ]
+
+__author__ = 'R. Oudkerk (r.m.oudkerk@gmail.com)'
+
+#
+# Imports
+#
+
+import os
+import sys
+
+import _multiprocessing
+from multiprocessing.process import Process, current_process, active_children
+
+#
+# Exceptions
+#
+
+class ProcessError(Exception):
+    pass
+    
+class BufferTooShort(ProcessError):
+    pass
+    
+class TimeoutError(ProcessError):
+    pass
+
+class AuthenticationError(ProcessError):
+    pass
+
+#
+# Definitions not depending on native semaphores
+#
+
+def Manager():
+    '''
+    Returns a manager associated with a running server process
+
+    The managers methods such as `Lock()`, `Condition()` and `Queue()`
+    can be used to create shared objects.
+    '''
+    from multiprocessing.managers import SyncManager
+    m = SyncManager()
+    m.start()
+    return m
+
+def Pipe(duplex=True):
+    '''
+    Returns two connection object connected by a pipe
+    '''
+    from multiprocessing.connection import Pipe
+    return Pipe(duplex)
+
+def cpu_count():
+    '''
+    Returns the number of CPUs in the system
+    '''
+    if sys.platform == 'win32':
+        try:
+            num = int(os.environ['NUMBER_OF_PROCESSORS'])
+        except (ValueError, KeyError):
+            num = 0
+    elif sys.platform == 'darwin':
+        try:
+            num = int(os.popen('sysctl -n hw.ncpu').read())
+        except ValueError:
+            num = 0
+    else:
+        try:
+            num = os.sysconf('SC_NPROCESSORS_ONLN')
+        except (ValueError, OSError, AttributeError):
+            num = 0
+        
+    if num >= 1:
+        return num
+    else:
+        raise NotImplementedError('cannot determine number of cpus')
+
+def freeze_support():
+    '''
+    Check whether this is a fake forked process in a frozen executable.
+    If so then run code specified by commandline and exit.
+    '''
+    if sys.platform == 'win32' and getattr(sys, 'frozen', False):
+        from multiprocessing.forking import freeze_support
+        freeze_support()
+
+def get_logger():
+    '''
+    Return package logger -- if it does not already exist then it is created
+    '''
+    from multiprocessing.util import get_logger
+    return get_logger()
+
+def log_to_stderr(level=None):
+    '''
+    Turn on logging and add a handler which prints to stderr
+    '''
+    from multiprocessing.util import log_to_stderr
+    return log_to_stderr(level)
+    
+def allow_connection_pickling():
+    '''
+    Install support for sending connections and sockets between processes
+    '''
+    from multiprocessing import reduction
+    
+#
+# Definitions depending on native semaphores
+#
+
+def Lock():
+    '''
+    Returns a non-recursive lock object
+    '''
+    from multiprocessing.synchronize import Lock
+    return Lock()
+
+def RLock():
+    '''
+    Returns a recursive lock object
+    '''
+    from multiprocessing.synchronize import RLock
+    return RLock()
+
+def Condition(lock=None):
+    '''
+    Returns a condition object
+    '''
+    from multiprocessing.synchronize import Condition
+    return Condition(lock)
+
+def Semaphore(value=1):
+    '''
+    Returns a semaphore object
+    '''
+    from multiprocessing.synchronize import Semaphore
+    return Semaphore(value)
+
+def BoundedSemaphore(value=1):
+    '''
+    Returns a bounded semaphore object
+    '''
+    from multiprocessing.synchronize import BoundedSemaphore
+    return BoundedSemaphore(value)
+
+def Event():
+    '''
+    Returns an event object
+    '''
+    from multiprocessing.synchronize import Event
+    return Event()
+
+def Queue(maxsize=0):
+    '''
+    Returns a queue object
+    '''
+    from multiprocessing.queues import Queue
+    return Queue(maxsize)
+
+def JoinableQueue(maxsize=0):
+    '''
+    Returns a queue object
+    '''
+    from multiprocessing.queues import JoinableQueue
+    return JoinableQueue(maxsize)
+
+def Pool(processes=None, initializer=None, initargs=()):
+    '''
+    Returns a process pool object
+    '''
+    from multiprocessing.pool import Pool
+    return Pool(processes, initializer, initargs)
+
+def RawValue(typecode_or_type, *args):
+    '''
+    Returns a shared object
+    '''
+    from multiprocessing.sharedctypes import RawValue
+    return RawValue(typecode_or_type, *args)
+
+def RawArray(typecode_or_type, size_or_initializer):
+    '''
+    Returns a shared array
+    '''
+    from multiprocessing.sharedctypes import RawArray
+    return RawArray(typecode_or_type, size_or_initializer)
+
+def Value(typecode_or_type, *args, **kwds):
+    '''
+    Returns a synchronized shared object
+    '''
+    from multiprocessing.sharedctypes import Value
+    return Value(typecode_or_type, *args, **kwds)
+
+def Array(typecode_or_type, size_or_initializer, **kwds):
+    '''
+    Returns a synchronized shared array
+    '''
+    from multiprocessing.sharedctypes import Array
+    return Array(typecode_or_type, size_or_initializer, **kwds)
+
+#
+#
+#
+
+if sys.platform == 'win32':
+
+    def set_executable(executable):
+        '''
+        Sets the path to a python.exe or pythonw.exe binary used to run
+        child processes on Windows instead of sys.executable.
+        Useful for people embedding Python. 
+        '''
+        from multiprocessing.forking import set_executable
+        set_executable(executable)
+
+    __all__ += ['set_executable']

Lib/multiprocessing/dummy/__init__.py

+#
+# Support for the API of the multiprocessing package using threads
+#
+# multiprocessing/dummy/__init__.py
+#
+# Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt
+#
+
+__all__ = [
+    'Process', 'current_process', 'active_children', 'freeze_support',
+    'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Condition',
+    'Event', 'Queue', 'Manager', 'Pipe', 'Pool', 'JoinableQueue'
+    ]
+
+#
+# Imports
+#
+
+import threading
+import sys
+import weakref
+import array
+import itertools
+
+from multiprocessing import TimeoutError, cpu_count
+from multiprocessing.dummy.connection import Pipe
+from threading import Lock, RLock, Semaphore, BoundedSemaphore
+from threading import Event
+from Queue import Queue
+
+#
+#
+#
+
+class DummyProcess(threading.Thread):
+
+    def __init__(self, group=None, target=None, name=None, args=(), kwargs={}):
+        threading.Thread.__init__(self, group, target, name, args, kwargs)
+        self._pid = None
+        self._children = weakref.WeakKeyDictionary()
+        self._start_called = False
+        self._parent = current_process()
+
+    def start(self):
+        assert self._parent is current_process()
+        self._start_called = True
+        self._parent._children[self] = None
+        threading.Thread.start(self)
+
+    def get_exitcode(self):
+        if self._start_called and not self.isAlive():
+            return 0
+        else:
+            return None
+
+    # XXX
+    if sys.version_info < (3, 0):
+        is_alive = threading.Thread.isAlive.im_func
+        get_name = threading.Thread.getName.im_func
+        set_name = threading.Thread.setName.im_func
+        is_daemon = threading.Thread.isDaemon.im_func
+        set_daemon = threading.Thread.setDaemon.im_func
+    else:
+        is_alive = threading.Thread.isAlive
+        get_name = threading.Thread.getName
+        set_name = threading.Thread.setName
+        is_daemon = threading.Thread.isDaemon
+        set_daemon = threading.Thread.setDaemon
+
+#
+#
+#
+        
+class Condition(threading._Condition):
+    # XXX
+    if sys.version_info < (3, 0):
+        notify_all = threading._Condition.notifyAll.im_func
+    else:
+        notify_all = threading._Condition.notifyAll
+
+#
+#
+#
+
+Process = DummyProcess
+current_process = threading.currentThread
+current_process()._children = weakref.WeakKeyDictionary()
+
+def active_children():
+    children = current_process()._children
+    for p in list(children):
+        if not p.isAlive():
+            children.pop(p, None)
+    return list(children)
+
+def freeze_support():
+    pass
+
+#
+#
+#
+
+class Namespace(object):
+    def __init__(self, **kwds):
+        self.__dict__.update(kwds)
+    def __repr__(self):
+        items = self.__dict__.items()
+        temp = []
+        for name, value in items:
+            if not name.startswith('_'):
+                temp.append('%s=%r' % (name, value))
+        temp.sort()
+        return 'Namespace(%s)' % str.join(', ', temp)
+
+dict = dict
+list = list
+
+def Array(typecode, sequence, lock=True):
+    return array.array(typecode, sequence)
+
+class Value(object):
+    def __init__(self, typecode, value, lock=True):
+        self._typecode = typecode
+        self._value = value
+    def _get(self):
+        return self._value
+    def _set(self, value):
+        self._value = value
+    value = property(_get, _set)
+    def __repr__(self):
+        return '<%r(%r, %r)>'%(type(self).__name__,self._typecode,self._value)
+
+def Manager():
+    return sys.modules[__name__]
+
+def shutdown():
+    pass
+
+def Pool(processes=None, initializer=None, initargs=()):
+    from multiprocessing.pool import ThreadPool
+    return ThreadPool(processes, initializer, initargs)
+
+JoinableQueue = Queue

Lib/multiprocessing/dummy/connection.py

+#
+# Analogue of `multiprocessing.connection` which uses queues instead of sockets
+#
+# multiprocessing/dummy/connection.py
+#
+# Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt
+#
+
+__all__ = [ 'Client', 'Listener', 'Pipe' ]
+
+from Queue import Queue
+
+
+families = [None]
+
+
+class Listener(object):
+
+    def __init__(self, address=None, family=None, backlog=1):
+        self._backlog_queue = Queue(backlog)
+
+    def accept(self):
+        return Connection(*self._backlog_queue.get())
+
+    def close(self):
+        self._backlog_queue = None
+
+    address = property(lambda self: self._backlog_queue)
+
+
+def Client(address):
+    _in, _out = Queue(), Queue()
+    address.put((_out, _in))
+    return Connection(_in, _out)
+
+
+def Pipe(duplex=True):
+    a, b = Queue(), Queue()
+    return Connection(a, b), Connection(b, a)
+
+
+class Connection(object):
+
+    def __init__(self, _in, _out):
+        self._out = _out
+        self._in = _in
+        self.send = self.send_bytes = _out.put
+        self.recv = self.recv_bytes = _in.get
+
+    def poll(self, timeout=0.0):
+        if self._in.qsize() > 0:
+            return True
+        if timeout <= 0.0:
+            return False
+        self._in.not_empty.acquire()
+        self._in.not_empty.wait(timeout)
+        self._in.not_empty.release()
+        return self._in.qsize() > 0
+
+    def close(self):
+        pass

setup.py

@@ -1236,6 +1236,58 @@ class PyBuildExt(build_ext):
         # Thomas Heller's _ctypes module
         self.detect_ctypes(inc_dirs, lib_dirs)
 
+        # Richard Oudkerk's multiprocessing module
+        if platform == 'win32':             # Windows
+            macros = dict()
+            libraries = ['ws2_32']
+
+        elif platform == 'darwin':          # Mac OSX
+            macros = dict(
+                HAVE_SEM_OPEN=1,
+                HAVE_SEM_TIMEDWAIT=0,
+                HAVE_FD_TRANSFER=1,
+                HAVE_BROKEN_SEM_GETVALUE=1
+                )
+            libraries = []
+
+        elif platform == 'cygwin':          # Cygwin
+            macros = dict(
+                HAVE_SEM_OPEN=1,
+                HAVE_SEM_TIMEDWAIT=1,
+                HAVE_FD_TRANSFER=0,
+                HAVE_BROKEN_SEM_UNLINK=1
+                )
+            libraries = []
+        else:                                   # Linux and other unices
+            macros = dict(
+                HAVE_SEM_OPEN=1,
+                HAVE_SEM_TIMEDWAIT=1,
+                HAVE_FD_TRANSFER=1
+                )
+            libraries = ['rt']
+
+        if platform == 'win32':
+            multiprocessing_srcs = [ '_multiprocessing/multiprocessing.c',
+                                     '_multiprocessing/semaphore.c',
+                                     '_multiprocessing/pipe_connection.c',
+                                     '_multiprocessing/socket_connection.c',
+                                     '_multiprocessing/win32_functions.c'
+                                   ]
+
+        else:
+            multiprocessing_srcs = [ '_multiprocessing/multiprocessing.c',
+                                     '_multiprocessing/socket_connection.c'
+                                   ]
+
+            if macros.get('HAVE_SEM_OPEN', False):
+                multiprocessing_srcs.append('_multiprocessing/semaphore.c')
+
+        exts.append ( Extension('_multiprocessing', multiprocessing_srcs,
+                                 define_macros=macros.items(),
+                                 include_dirs=["Modules/_multiprocessing"]))
+        # End multiprocessing
+
+
         # Platform-specific libraries
         if platform == 'linux2':
             # Linux-specific modules