示例
標準線程多進程，生產者/消費者示例：
Worker越多,問題越大
# -*- coding: utf8 -*-
import os
import time
import Queue
import threading
from PIL import Image
def create_thumbnail(filename, size=(128, 128)):
??? try:
??????? fp, fmt = filename.rsplit('.', 1)
??????? im = Image.open(filename)
??????? im.thumbnail(size, Image.ANTIALIAS)
??????? im.save((fp + '_'+'x'.join(str(i) for i in size) + '.'+fmt), im.format)
??????? return '%s thumbnail success!' % filename
??? except Exception:
??????? return '%s thumbnail failed!' % filename
def get_image_paths(folder):
??? return [os.path.join(folder, f) for f in os.listdir(folder) if 'png' in f]
class Consumer(threading.Thread):
??? def __init__(self, queue):
??????? threading.Thread.__init__(self)
??????? self._queue = queue
??? def run(self):
??????? while True:
??????????? content = self._queue.get()
??????????? if isinstance(content, str) and content == 'quit':
??????????????? break
??????????? respone = create_thumbnail(content)
??????? print 'Bye bye!'
def Producer():
??? filenames = get_image_paths('images')
??? queue = Queue.Queue()
??? worker_threads = build_worker_pool(queue, 4)
??? start_time = time.time()
??? for filename in filenames:
??????? queue.put(filename)
??? for worker in worker_threads:
??????? queue.put('quit')
??? for worker in worker_threads:
??????? worker.join()
??? print time.time() - start_time
def build_worker_pool(queue, size):
??? workers = []
??? for _ in range(size):
??????? worker = Consumer(queue)
??????? worker.start()
??????? workers.append(worker)
??? return workers
if __name__ == '__main__':
??? Producer()
map
Map能夠處理集合按順序遍歷，最終將調用產生的結果保存在一個簡單的集合當中。
# -*- coding: utf8 -*-
import os
import time
from multiprocessing import Pool
from PIL import Image
def create_thumbnail(filename, size=(128, 128)):
??? try:
??????? fp, fmt = filename.rsplit('.', 1)
??????? im = Image.open(filename)
??????? im.thumbnail(size, Image.ANTIALIAS)
??????? im.save((fp + '_'+'x'.join(str(i) for i in size) + '.'+fmt), im.format)
??????? return '%s thumbnail success!' % filename
??? except Exception:
??????? return '%s thumbnail failed!' % filename
def get_image_paths(folder):
??? return [os.path.join(folder, f) for f in os.listdir(folder) if 'png' in f]
def main():
??? filenames = get_image_paths('images')
??? start_time = time.time()
???
??? pool = Pool(4)
??? pool.map(create_thumbnail, filenames)
??? pool.close()
??? pool.join()
??? print time.time() - start_time
if __name__ == '__main__':
??? main()
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