Python 正确使用带生成器的线程池
在Python2.7中处理CSV文件时,我无法将Python 正确使用带生成器的线程池,python,multiprocessing,threadpool,python-multiprocessing,yield-keyword,Python,Multiprocessing,Threadpool,Python Multiprocessing,Yield Keyword,在Python2.7中处理CSV文件时,我无法将ThreadPools与生成器一起使用。下面是一些示例代码,说明了我的观点: from multiprocessing.dummy import Pool as ThreadPool import time def getNextBatch(): # Reads lines from a huge CSV and yields them as required. for i in range(5): yield i
ThreadPool
s与生成器一起使用。下面是一些示例代码,说明了我的观点:
from multiprocessing.dummy import Pool as ThreadPool
import time
def getNextBatch():
# Reads lines from a huge CSV and yields them as required.
for i in range(5):
yield i;
def processBatch(batch):
# This simulates a slow network request that happens.
time.sleep(1);
print "Processed Batch " + str(batch);
# We use 4 threads to attempt to aleviate the bottleneck caused by network I/O.
threadPool = ThreadPool(processes = 4)
batchGenerator = getNextBatch()
for batch in batchGenerator:
threadPool.map(processBatch, (batch,))
threadPool.close()
threadPool.join()
当我运行此命令时,我得到了预期的输出:
已处理批0
加工批次1
加工批次2
加工批次3
加工批次4
问题是它们在每次打印之间出现1秒延迟。实际上,我的脚本是按顺序运行的(而不是像我希望的那样使用多个线程)
这里的目标是让打印出来的语句在1秒钟后全部显示,而不是在5秒钟内每秒显示一条语句。这是您的问题
for batch in batchGenerator:
threadPool.map(processBatch, (batch,))
当我试着
threadPool.map(processBatch,batchGenerator)
它按预期工作(但不按顺序)。for循环使用线程池一次一个地处理每个批。所以它完成了一个,然后继续,然后