<p>您可以迭代<code>keys()</code>以减少内存占用。你得防止钥匙被删除。</p>
<p>否则,这里有一个具有两种不同方式的示例,可以让您迭代dict中的项。此示例中的<code>iteritems()</code>方法仅适用于创建manager对象的进程和manager对象创建的子进程。这是因为需要manager对象来创建新的代理,而其他进程无权访问它。<code>iteritems2()</code>方法从其他进程工作,因为它不依赖于在这些进程中创建新代理。</p>
<pre><code>import multiprocessing as mp
import multiprocessing.managers
class mydict(dict):
def __init__(self, *args, **kwargs):
dict.__init__(self, *args, **kwargs)
self.iters = {}
def iteritems(self):
print "iteritems", mp.current_process()
return dict.iteritems(self)
def _iteritems_start(self):
print "_iteritems_start", mp.current_process()
i = dict.iteritems(self)
self.iters[id(i)] = i
return id(i)
def _iteritems_next(self, iter_id):
try:
return self.iters[iter_id].next()
except StopIteration:
del self.iters[iter_id]
return None
class mydict_proxy(mp.managers.DictProxy):
def iteritems(self):
print "iteritems proxy", mp.current_process()
return self._callmethod("iteritems")
def iteritems2(self):
print "iteritems2 proxy", mp.current_process()
iter_id = self._callmethod("_iteritems_start")
def generator():
while True:
a = self._callmethod("_iteritems_next",
(iter_id,))
if a == None:
return
yield a
return generator()
_method_to_typeid_ = { "iteritems": "Iterator" }
_exposed_ = mp.managers.DictProxy._exposed_
_exposed_ += ("iteritems", "_iteritems_start", "_iteritems_next")
class mymanager(mp.managers.BaseManager):
pass
mymanager.register("mydict", mydict, mydict_proxy)
mymanager.register("Iterator", proxytype = mp.managers.IteratorProxy,
create_method = False)
def other(d):
for k, v in d.iteritems2():
d[k] = v.lower()
for k, v in d.iteritems():
d[k] = ord(v)
def main():
manager = mymanager()
manager.start()
d = manager.mydict(list(enumerate("ABCDEFGHIJKLMNOP")))
for (k, v) in d.iteritems():
print k, v
proc = mp.Process(target = other, args = (d,))
proc.start()
proc.join()
for (k, v) in d.iteritems():
print k, v
if __name__ == "__main__":
main()
</code></pre>
<p>请注意,虽然这段代码可能更节省内存,但可能会慢得多。</p>