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Kirill Smelkov
cpython
Commits
4523968b
Commit
4523968b
authored
Nov 28, 2008
by
Jesse Noller
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Merge r67419 to py3k, mp doc fixes
parent
7ca7cb48
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Doc/library/multiprocessing.rst
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Doc/library/multiprocessing.rst
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4523968b
...
...
@@ -24,6 +24,29 @@ Windows.
import it will result in an :exc:`ImportError`. See
:issue:`3770` for additional information.
.. note::
Functionality within this package requires that the ``__main__`` method be
importable by the children. This is covered in :ref:`multiprocessing-programming`
however it is worth pointing out here. This means that some examples, such
as the :class:`multiprocessing.Pool` examples will not work in the
interactive interpreter. For example::
>>> from multiprocessing import Pool
>>> p = Pool(5)
>>> def f(x):
... return x*x
...
>>> p.map(f, [1,2,3])
Process PoolWorker-1:
Process PoolWorker-2:
Traceback (most recent call last):
Traceback (most recent call last):
AttributeError: '
module
' object has no attribute '
f
'
AttributeError: '
module
' object has no attribute '
f
'
AttributeError: '
module
' object has no attribute '
f
'
The :class:`Process` class
~~~~~~~~~~~~~~~~~~~~~~~~~~
...
...
@@ -32,17 +55,36 @@ object and then calling its :meth:`~Process.start` method. :class:`Process`
follows the API of :class:`threading.Thread`. A trivial example of a
multiprocess program is ::
from multiprocessing import Process
from multiprocessing import Process
def f(name):
print('
hello
', name)
if __name__ == '
__main__
':
p = Process(target=f, args=('
bob
',))
p.start()
p.join()
Here the function ``f`` is run in a child process.
if __name__ == '
__main__
':
p = Process(target=f, args=('
bob
',))
p.start()
p.join()
To show the individual process IDs involved, here is an expanded example::
from multiprocessing import Process
import os
def info(title):
print title
print '
module
name
:
', __name__
print '
parent
process
:
', os.getppid()
print '
process
id
:
', os.getpid()
def f(name):
info('
function
f
')
print '
hello
', name
if __name__ == '
__main__
':
info('
main
line
')
p = Process(target=f, args=('
bob
',))
p.start()
p.join()
For an explanation of why (on Windows) the ``if __name__ == '
__main__
'`` part is
necessary, see :ref:`multiprocessing-programming`.
...
...
@@ -231,10 +273,10 @@ For example::
return x*x
if __name__ == '
__main__
':
pool = Pool(processes=4) # start 4 worker processes
result = pool.apply_async(f, [10]) # evaluate "f(10)" asynchronously
print
(result.get(timeout=1))
# prints "100" unless your computer is *very* slow
print
(pool.map(f, range(10)))
# prints "[0, 1, 4,..., 81]"
pool = Pool(processes=4)
# start 4 worker processes
result = pool.apply_async(f, [10])
# evaluate "f(10)" asynchronously
print
result.get(timeout=1)
# prints "100" unless your computer is *very* slow
print
pool.map(f, range(10))
# prints "[0, 1, 4,..., 81]"
Reference
...
...
@@ -305,7 +347,7 @@ The :mod:`multiprocessing` package mostly replicates the API of the
semantics
.
Multiple
processes
may
be
given
the
same
name
.
The
initial
name
is
set
by
the
constructor
.
..
method
::
is_alive
()
..
method
::
is_alive
Return
whether
the
process
is
alive
.
...
...
@@ -814,6 +856,9 @@ object -- see :ref:`multiprocessing-managers`.
acceptable
.
If
*
block
*
is
``
True
``
and
*
timeout
*
is
not
``
None
``
then
it
specifies
a
timeout
in
seconds
.
If
*
block
*
is
``
False
``
then
*
timeout
*
is
ignored
.
Note
that
on
OS
/
X
``
sem_timedwait
``
is
unsupported
,
so
timeout
arguments
for
these
will
be
ignored
.
..
note
::
...
...
@@ -1087,6 +1132,27 @@ their parent process exits. The manager classes are defined in the
A
class
method
which
creates
a
manager
object
referring
to
a
pre
-
existing
server
process
which
is
using
the
given
address
and
authentication
key
.
..
method
::
get_server
()
Returns
a
:
class
:`
Server
`
object
which
represents
the
actual
server
under
the
control
of
the
Manager
.
The
:
class
:`
Server
`
object
supports
the
:
meth
:`
serve_forever
`
method
::
>>>
from
multiprocessing
.
managers
import
BaseManager
>>>
m
=
BaseManager
(
address
=(
''
,
50000
),
authkey
=
'abc'
))
>>>
server
=
m
.
get_server
()
>>>
s
.
serve_forever
()
:
class
:`
Server
`
additionally
have
an
:
attr
:`
address
`
attribute
.
..
method
::
connect
()
Connect
a
local
manager
object
to
a
remote
manager
process
::
>>>
from
multiprocessing
.
managers
import
BaseManager
>>>
m
=
BaseManager
(
address
=
'127.0.0.1'
,
authkey
=
'abc))
>>> m.connect()
.. method:: shutdown()
Stop the process used by the manager. This is only available if
...
...
@@ -1265,19 +1331,20 @@ remote clients can access::
>>> queue = queue.Queue()
>>> class QueueManager(BaseManager): pass
...
>>>
QueueManager
.
register
(
'get
Q
ueue'
,
callable
=
lambda
:
queue
)
>>> QueueManager.register('
get
_q
ueue
', callable=lambda:queue)
>>> m = QueueManager(address=('', 50000), authkey='
abracadabra
')
>>>
m
.
serveForever
()
>>> s = m.get_server()
>>> s.serveForever()
One client can access the server as follows::
>>> from multiprocessing.managers import BaseManager
>>> class QueueManager(BaseManager): pass
...
>>>
QueueManager
.
register
(
'get
Q
ueue'
)
>>>
m
=
QueueManager
.
from_address
(
address
=(
'foo.bar.org'
,
50000
),
>>>
authkey
=
'abracadabra'
)
>>>
queue
=
m
.
get
Q
ueue
()
>>> QueueManager.register('
get
_q
ueue
')
>>> m = QueueManager
(address=('
foo
.
bar
.
org
', 50000), authkey='
abracadabra
')
>>>
m.connect(
)
>>> queue = m.get
_q
ueue()
>>> queue.put('
hello
')
Another client can also use it::
...
...
@@ -1291,6 +1358,27 @@ Another client can also use it::
>>> queue.get()
'
hello
'
Local processes can also access that queue, using the code from above on the
client to access it remotely::
>>> from multiprocessing import Process, Queue
>>> from multiprocessing.managers import BaseManager
>>> class Worker(Process):
... def __init__(self, q):
... self.q = q
... super(Worker, self).__init__()
... def run(self):
... self.q.put('
local
hello
')
...
>>> queue = Queue()
>>> w = Worker(queue)
>>> w.start()
>>> class QueueManager(BaseManager): pass
...
>>> QueueManager.register('
get_queue
', callable=lambda: queue)
>>> m = QueueManager(address=('', 50000), authkey='
abracadabra
')
>>> s = m.get_server()
>>> s.serve_forever()
Proxy Objects
~~~~~~~~~~~~~
...
...
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