Re: problem with multiprocessing and defaultdict
Robert Kern wrote: On 2010-01-11 17:50 PM, wiso wrote: The problem now is this: start reading file r1_200909.log start reading file r1_200910.log readen 488832 lines from file r1_200910.log readen 517247 lines from file r1_200909.log with huge file (the real case) the program freeze. Is there a solution to avoid pickling/serialization, ... for example something like this: if __name__ == __main__: file_names = [r1_200909.log, r1_200910.log] pool = multiprocessing.Pool(len(file_names)) childrens = [Container(f) for f in file_names] pool.map(lambda c: c.read(), childrens) PicklingError: Can't pickletype 'function': attribute lookup __builtin__.function failed You can't pickle lambda functions. What information do you actually need back from the workers? They sent back the object filled with data. The problem is very simple: I have a container, the container has a method read(file_name) that read a huge file and fill the container with datas. I have more then 1 file to read so I want to parallelize this process. The reading method is quite slow because it involves regex. -- http://mail.python.org/mailman/listinfo/python-list
Re: problem with multiprocessing and defaultdict
On Tue, Jan 12, 2010 at 11:48 +0100, wiso wrote: They sent back the object filled with data. The problem is very simple: I have a container, the container has a method read(file_name) that read a huge file and fill the container with datas. I have more then 1 file to read so I want to parallelize this process. The reading method is quite slow because it involves regex. Take a look at multiprocessing.Manager and use one to proxy access to a *shared* container to your container from all processes. If your container is a dict it is as easy as: manager = multiprocessing.Manager() managed_dict = manager.dict() ... -- .''`. Wolodja Wentlandwentl...@cl.uni-heidelberg.de : :' : `. `'` 4096R/CAF14EFC `- 081C B7CD FF04 2BA9 94EA 36B2 8B7F 7D30 CAF1 4EFC signature.asc Description: Digital signature -- http://mail.python.org/mailman/listinfo/python-list
problem with multiprocessing and defaultdict
I'm using a class to read some data from files:
import multiprocessing
from collections import defaultdict
def SingleContainer():
return list()
class Container(defaultdict):
this class store odd line in self[odd] and even line in self[even].
It is stupid, but it's only an example.
def __init__(self,file_name):
if type(file_name) != str:
raise AttributeError, %s is not a string % file_name
defaultdict.__init__(self,SingleContainer)
self.file_name = file_name
self.readen_lines = 0
def read(self):
f = open(self.file_name)
print start reading file %s % self.file_name
for line in f:
self.readen_lines += 1
values = line.split()
key = {0: even, 1: odd}[self.readen_lines %2]
self[key].append(values)
print readen %d lines from file %s % (self.readen_lines,
self.file_name)
Now I want to read more than one file per times
def do(file_name):
container = Container(file_name)
container.read()
return container
if __name__ == __main__:
file_names = [prova_200909.log, prova_200910.log]
pool = multiprocessing.Pool(len(file_names))
result = pool.map(do,file_names)
pool.close()
pool.join()
print Finish
but I got:
start reading file prova_200909.log
start reading file prova_200910.log
readen 142 lines from file prova_200909.log
readen 160 lines from file prova_200910.log
Exception in thread Thread-2:
Traceback (most recent call last):
File /usr/lib64/python2.6/threading.py, line 522, in __bootstrap_inner
self.run()
File /usr/lib64/python2.6/threading.py, line 477, in run
self.__target(*self.__args, **self.__kwargs)
File /usr/lib64/python2.6/multiprocessing/pool.py, line 259, in
_handle_results
task = get()
File main2.py, line 11, in __init__
raise AttributeError, %s is not a string % file_name
AttributeError: (AttributeError('function SingleContainer at
0x7f08b253d938 is not a string',), class '__main__.Container', (function
SingleContainer at 0x7f08b253d938,))
the problem is when pool share objects, but why is it calling
Container.__init__ with a Container parameter?
--
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Re: problem with multiprocessing and defaultdict
On 2010-01-11 17:15 PM, wiso wrote:
I'm using a class to read some data from files:
import multiprocessing
from collections import defaultdict
def SingleContainer():
return list()
class Container(defaultdict):
this class store odd line in self[odd] and even line in self[even].
It is stupid, but it's only an example.
def __init__(self,file_name):
if type(file_name) != str:
raise AttributeError, %s is not a string % file_name
defaultdict.__init__(self,SingleContainer)
self.file_name = file_name
self.readen_lines = 0
def read(self):
f = open(self.file_name)
print start reading file %s % self.file_name
for line in f:
self.readen_lines += 1
values = line.split()
key = {0: even, 1: odd}[self.readen_lines %2]
self[key].append(values)
print readen %d lines from file %s % (self.readen_lines,
self.file_name)
Now I want to read more than one file per times
def do(file_name):
container = Container(file_name)
container.read()
return container
if __name__ == __main__:
file_names = [prova_200909.log, prova_200910.log]
pool = multiprocessing.Pool(len(file_names))
result = pool.map(do,file_names)
pool.close()
pool.join()
print Finish
but I got:
start reading file prova_200909.log
start reading file prova_200910.log
readen 142 lines from file prova_200909.log
readen 160 lines from file prova_200910.log
Exception in thread Thread-2:
Traceback (most recent call last):
File /usr/lib64/python2.6/threading.py, line 522, in __bootstrap_inner
self.run()
File /usr/lib64/python2.6/threading.py, line 477, in run
self.__target(*self.__args, **self.__kwargs)
File /usr/lib64/python2.6/multiprocessing/pool.py, line 259, in
_handle_results
task = get()
File main2.py, line 11, in __init__
raise AttributeError, %s is not a string % file_name
AttributeError: (AttributeError('function SingleContainer at
0x7f08b253d938 is not a string',),class '__main__.Container', (function
SingleContainer at 0x7f08b253d938,))
the problem is when pool share objects, but why is it calling
Container.__init__ with a Container parameter?
When you return the container from do() in the worker process, it must be
pickled in order to be sent over the socket. You did not override the
implementation of the .__reduce_ex__() method, so it used defaultdict's version
which passes the factory function as the first argument to the constructor.
I would recommend passing back the container.items() list instead of a Container
instance as the easiest path forward.
--
Robert Kern
I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth.
-- Umberto Eco
--
http://mail.python.org/mailman/listinfo/python-list
Re: problem with multiprocessing and defaultdict
Robert Kern wrote:
On 2010-01-11 17:15 PM, wiso wrote:
I'm using a class to read some data from files:
import multiprocessing
from collections import defaultdict
def SingleContainer():
return list()
class Container(defaultdict):
this class store odd line in self[odd] and even line in
self[even]. It is stupid, but it's only an example.
def __init__(self,file_name):
if type(file_name) != str:
raise AttributeError, %s is not a string % file_name
defaultdict.__init__(self,SingleContainer)
self.file_name = file_name
self.readen_lines = 0
def read(self):
f = open(self.file_name)
print start reading file %s % self.file_name
for line in f:
self.readen_lines += 1
values = line.split()
key = {0: even, 1: odd}[self.readen_lines %2]
self[key].append(values)
print readen %d lines from file %s % (self.readen_lines,
self.file_name)
Now I want to read more than one file per times
def do(file_name):
container = Container(file_name)
container.read()
return container
if __name__ == __main__:
file_names = [prova_200909.log, prova_200910.log]
pool = multiprocessing.Pool(len(file_names))
result = pool.map(do,file_names)
pool.close()
pool.join()
print Finish
but I got:
start reading file prova_200909.log
start reading file prova_200910.log
readen 142 lines from file prova_200909.log
readen 160 lines from file prova_200910.log
Exception in thread Thread-2:
Traceback (most recent call last):
File /usr/lib64/python2.6/threading.py, line 522, in
__bootstrap_inner
self.run()
File /usr/lib64/python2.6/threading.py, line 477, in run
self.__target(*self.__args, **self.__kwargs)
File /usr/lib64/python2.6/multiprocessing/pool.py, line 259, in
_handle_results
task = get()
File main2.py, line 11, in __init__
raise AttributeError, %s is not a string % file_name
AttributeError: (AttributeError('function SingleContainer at
0x7f08b253d938 is not a string',),class '__main__.Container',
(function SingleContainer at 0x7f08b253d938,))
the problem is when pool share objects, but why is it calling
Container.__init__ with a Container parameter?
When you return the container from do() in the worker process, it must be
pickled in order to be sent over the socket. You did not override the
implementation of the .__reduce_ex__() method, so it used defaultdict's
version which passes the factory function as the first argument to the
constructor.
I would recommend passing back the container.items() list instead of a
Container instance as the easiest path forward.
Thank you very much, I change from
return container
to
return container.items()
and it works:
start reading file prova_200909.log
readen 142 lines from file prova_200909.log
start reading file prova_200910.log
readen 160 lines from file prova_200910.log
Finish
The problem now is this:
start reading file r1_200909.log
start reading file r1_200910.log
readen 488832 lines from file r1_200910.log
readen 517247 lines from file r1_200909.log
with huge file (the real case) the program freeze. Is there a solution to
avoid pickling/serialization, ... for example something like this:
if __name__ == __main__:
file_names = [r1_200909.log, r1_200910.log]
pool = multiprocessing.Pool(len(file_names))
childrens = [Container(f) for f in file_names]
pool.map(lambda c: c.read(), childrens)
PicklingError: Can't pickle type 'function': attribute lookup
__builtin__.function failed
--
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Re: problem with multiprocessing and defaultdict
On 2010-01-11 17:50 PM, wiso wrote: The problem now is this: start reading file r1_200909.log start reading file r1_200910.log readen 488832 lines from file r1_200910.log readen 517247 lines from file r1_200909.log with huge file (the real case) the program freeze. Is there a solution to avoid pickling/serialization, ... for example something like this: if __name__ == __main__: file_names = [r1_200909.log, r1_200910.log] pool = multiprocessing.Pool(len(file_names)) childrens = [Container(f) for f in file_names] pool.map(lambda c: c.read(), childrens) PicklingError: Can't pickletype 'function': attribute lookup __builtin__.function failed You can't pickle lambda functions. What information do you actually need back from the workers? -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco -- http://mail.python.org/mailman/listinfo/python-list
