[英]Is there a Python library equivalent of the Java's FixedThreadPool?
Is there a simple ThreadPool library in Python that has, for example, pool.execute(function, args) method, which should be blocked when the pool is full (until one of the threads becomes free)? 在Python中是否有一个简单的ThreadPool库,例如,pool.execute(function,args)方法,当池已满时应该被阻塞(直到其中一个线程变为空闲)?
I have tried using ThreadPool from multiprocessing package, but its pool.apply_async() function doesn't block when the pool is full. 我尝试过使用多处理程序包中的ThreadPool,但是当池已满时,它的pool.apply_async()函数不会阻塞。 Actually, I don't get its behavior at all. 实际上,我根本没有得到它的行为。
This ActiveState Code Recipes page has an implementation based on a Python queue to do the blocking. 此ActiveState代码配方页面具有基于Python队列的实现以执行阻止。 Use add_task
where you would execute
. 使用add_task
execute
。
## {{{ http://code.activestate.com/recipes/577187/ (r9)
from Queue import Queue
from threading import Thread
class Worker(Thread):
"""Thread executing tasks from a given tasks queue"""
def __init__(self, tasks):
Thread.__init__(self)
self.tasks = tasks
self.daemon = True
self.start()
def run(self):
while True:
func, args, kargs = self.tasks.get()
try: func(*args, **kargs)
except Exception, e: print e
self.tasks.task_done()
class ThreadPool:
"""Pool of threads consuming tasks from a queue"""
def __init__(self, num_threads):
self.tasks = Queue(num_threads)
for _ in range(num_threads): Worker(self.tasks)
def add_task(self, func, *args, **kargs):
"""Add a task to the queue"""
self.tasks.put((func, args, kargs))
def wait_completion(self):
"""Wait for completion of all the tasks in the queue"""
self.tasks.join()
if __name__ == '__main__':
from random import randrange
delays = [randrange(1, 10) for i in range(100)]
from time import sleep
def wait_delay(d):
print 'sleeping for (%d)sec' % d
sleep(d)
# 1) Init a Thread pool with the desired number of threads
pool = ThreadPool(20)
for i, d in enumerate(delays):
# print the percentage of tasks placed in the queue
print '%.2f%c' % ((float(i)/float(len(delays)))*100.0,'%')
# 2) Add the task to the queue
pool.add_task(wait_delay, d)
# 3) Wait for completion
pool.wait_completion()
## end of http://code.activestate.com/recipes/577187/ }}}
I modified @ckhan answer and added a callback feature. 我修改了@ckhan的答案,并添加了一个回调功能。
#Custom ThreadPool implementation from http://code.activestate.com/recipes/577187/
# Usage:
# def worker_method(data):
# ''' do processing '''
# return data
#
# def on_complete_callback(data, isfailed):
# print ('on complete %s' % data)
#
# pool = ThreadPool(5)
# for data in range(1,10)
# pool.add_task(worker_method, on_complete_callback, data)
# pool.wait_completion()
from Queue import Queue
from threading import Thread
import thread
class Worker(Thread):
"""Thread executing tasks from a given tasks queue"""
def __init__(self, tasks, thread_id):
Thread.__init__(self)
self.tasks = tasks
self.daemon = True
self.start()
self.thread_id = thread_id
def run(self):
while True:
func, callback, args, kargs = self.tasks.get()
try:
data = func(*args, **kargs)
callback(data, False)
except Exception, e:
callback(e, True)
self.tasks.task_done()
class ThreadPool:
"""Pool of threads consuming tasks from a queue"""
def __init__(self, num_threads):
self.tasks = Queue(num_threads)
for i in range(num_threads): Worker(self.tasks, i)
def add_task(self, func, callback, *args, **kargs):
"""Add a task to the queue"""
self.tasks.put((func, callback, args, kargs))
def wait_completion(self):
"""Wait for completion of all the tasks in the queue"""
self.tasks.join()
from multiprocessing.pool import ThreadPool
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