python-multiprocessing

Progress measuring with python's multiprocessing Pool and map function

坚强是说给别人听的谎言 提交于 2019-12-05 02:38:38
问题 Following code I'm using for parallel csv processing: #!/usr/bin/env python import csv from time import sleep from multiprocessing import Pool from multiprocessing import cpu_count from multiprocessing import current_process from pprint import pprint as pp def init_worker(x): sleep(.5) print "(%s,%s)" % (x[0],x[1]) x.append(int(x[0])**2) return x def parallel_csv_processing(inputFile, outputFile, header=["Default", "header", "please", "change"], separator=",", skipRows = 0, cpuCount = 1): #

Where is the memory leak? How to timeout threads during multiprocessing in python?

隐身守侯 提交于 2019-12-05 02:24:01
It is unclear how to properly timeout workers of joblib's Parallel in python. Others have had similar questions here , here , here and here . In my example I am utilizing a pool of 50 joblib workers with threading backend. Parallel Call (threading): output = Parallel(n_jobs=50, backend = 'threading') (delayed(get_output)(INPUT) for INPUT in list) Here, Parallel hangs without errors as soon as len(list) <= n_jobs but only when n_jobs => -1 . In order to circumvent this issue, people give instructions on how to create a timeout decorator to the Parallel function ( get_output(INPUT) ) in the

How to get around the pickling error of python multiprocessing without being in the top-level?

大兔子大兔子 提交于 2019-12-04 21:36:18
问题 I've researched this question multiple times, but haven't found a workaround that either works in my case, or one that I understand, so please bear with me. Basically, I have a hierarchical organization of functions, and that is preventing me from multiprocessing in the top-level. Unfortunately, I don't believe I can change the layout of the program - because I need all the variables that I create after the initial inputs. For example, say I have this: import multiprocessing def calculate(x):

AttributeError: 'Pool' object has no attribute '__exit__'

隐身守侯 提交于 2019-12-04 21:16:28
问题 I'm doing some multiprocessing python scripts using multiprocessing.Pool . These scripts look like the following: from multiprocessing import Pool def f(x): return x*x if __name__ == '__main__': with Pool(processes=4) as pool: # start 4 worker processes print(pool.map(f, range(10))) # prints "[0, 1, 4,..., 81]" When running this with Python 3.4, everything is fine. However, when using Python 2.6 or 3.1 I get this error: AttributeError: 'Pool' object has no attribute '__exit__' Using Python 2

Multiprocessing using chunks does not work with predict_proba

*爱你&永不变心* 提交于 2019-12-04 20:45:24
When I run predict_proba on a dataframe without multiprocessing I get the expected behavior. The code is as follows: probabilities_data = classname.perform_model_prob_predictions_nc(prediction_model, vectorized_data) where: perform_model_prob_predictions_nc is: def perform_model_prob_predictions_nc(model, dataFrame): try: return model.predict_proba(dataFrame) except AttributeError: logging.error("AttributeError occurred",exc_info=True) But when I try to run the same function using chunks and multiprocessing: probabilities_data = classname.perform_model_prob_predictions(prediction_model, chunks

Python manager.dict() is very slow compared to regular dict

℡╲_俬逩灬. 提交于 2019-12-04 19:23:28
问题 I have a dict to store objects: jobs = {} job = Job() jobs[job.name] = job now I want to convert it to use manager dict because I want to use multiprocessing and need to share this dict amonst processes mgr = multiprocessing.Manager() jobs = mgr.dict() job = Job() jobs[job.name] = job just by converting to use manager.dict() things got extremely slow. For example, if using native dict, it only took .65 seconds to create 625 objects and store it into the dict. The very same task now takes 126

Parallel multiprocessing in python easy example

故事扮演 提交于 2019-12-04 18:24:53
I need to say that multiprocessing is something new to me. I read some about it but it makes me more confused. I want to understand it on a simple example. Let's assume that we have 2 functions in first one I just increment 'a' variable and then assign it to 'number' variable, in second I start first function and each every one second I want to print 'number' variable. It should looks like: global number def what_number(): a=1 while True: a+=1 number=a def read_number(): while True: --> #here I need to start 'what_number' function <-- time.sleep(1) print(number) if __name__ == "__main__": read

Python multiprocessing throws error with argparse and pyinstaller

ε祈祈猫儿з 提交于 2019-12-04 18:06:26
In my project, I'm using argprse to pass arguments and somewhere in script I'm using multiprocessing to do rest of the calculations. Script is working fine if I call it from command prompt for ex. " python complete_script.py --arg1=xy --arg2=yz " . But after converting it to exe using Pyinstaller using command "pyinstaller --onefile complete_script.py" it throws error " error: unrecognized arguments: --multiprocessing-fork 1448" Any suggestions how could I make this work. Or any other alternative. My goal is to create an exe application which I can call in other system where Python is not

Is it possible to parallelize selenium webdriver get_attribute calls in python?

♀尐吖头ヾ 提交于 2019-12-04 17:25:40
I am running this code from multiprocessing.Pool import ThreadPool from selenium import webdriver driver = webdriver.Firefox() driver.get(url) elements = driver.find_elements_by_class_name("class-name") pool = ThreadPool(4) async = [pool.apply_async(fn_which_calls_get_attribute,(element,)) for element in elements] results = [result.get() for result in async] which works fine for some of the results, but throws an error of ResponseNotReady for other results. It runs as expected if I use "pool.apply" instead of the async version. Is it a problem that I am making multiple calls to the selenium

Does multiprocessing copy the object in this scenario?

做~自己de王妃 提交于 2019-12-04 17:00:38
import multiprocessing import numpy as np import multiprocessing as mp import ctypes class Test(): def __init__(self): shared_array_base = multiprocessing.Array(ctypes.c_double, 100, lock=False) self.a = shared_array = np.ctypeslib.as_array(shared_array_base) def my_fun(self,i): self.a[i] = 1 if __name__ == "__main__": num_cores = multiprocessing.cpu_count() t = Test() def my_fun_wrapper(i): t.my_fun(i) with mp.Pool(num_cores) as p: p.map(my_fun_wrapper, np.arange(100)) print(t.a) In the code above, I'm trying to write a code to modify an array, using multiprocessing . The function my_fun() ,