使用threadpool的网站抓取工具:
import sys
from urllib import urlopen
from BeautifulSoup import BeautifulSoup, SoupStrainer
import re
from Queue import Queue, Empty
from threading import Thread
W_WAIT = 1
W_WORK = 0
class Worker(Thread):
"""Thread executing tasks from a given tasks queue"""
def __init__(self, pool, tasks):
Thread.__init__(self)
self.tasks = tasks
self.daemon = True
self.start()
self.pool = pool
self.state = None
def is_wait(self):
return self.state == W_WAIT
def run(self):
while True:
#if all workers wait - time to exsit
print "CHECK WAIT: !!! ",self.pool.is_all_wait()
if self.pool.is_all_wait():
print "ALL WAIT - CAN FINISH!"
return
try:
func, args, kargs = self.tasks.get(timeout=3)
except Empty:
print "task wait timeout"
continue
self.state = W_WORK
print "START !!! in thread %s" % str(self)
#print args
try: func(*args, **kargs)
except Exception, e: print e
print "!!! STOP in thread %s", str(self)
self.tasks.task_done()
self.state = W_WAIT
#threads can fast empty it!
#if self.tasks.qsize() == 0:
# print "QUIT!!!!!!"
# break
class ThreadPool:
"""Pool of threads consuming tasks from a queue"""
def __init__(self, num_threads):
#self.tasks = Queue(num_threads)
self.tasks = Queue()
self.workers = []
for _ in range(num_threads):
self.workers.append(Worker(self,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()
def is_all_wait(self):
for w in self.workers:
if not w.is_wait():
return False
return True
visited = set()
queue = Queue()
external_links_set = set()
internal_links_set = set()
external_links = 0
def process(pool,host,url):
try:
content = urlopen(url).read()
except UnicodeDecodeError:
return
for link in BeautifulSoup(content, parseOnlyThese=SoupStrainer('a')):
try:
href = link['href']
except KeyError:
continue
if not href.startswith('http://'):
href = 'http://%s%s' % (host, href)
if not href.startswith('http://%s%s' % (host, '/')):
continue
internal_links_set.add(href)
if href not in visited:
visited.add(href)
pool.add_task(process,pool,host,href)
else:
pass
def start(host,charset):
pool = ThreadPool(20)
pool.add_task(process,pool,host,'http://%s/' % (host))
pool.wait_completion()
start('evgenm.com','utf8')
Thanx寻求帮助!我做了新的实现: 你能对这段代码#2说些什么? ==================================尝试#2 ============= ==========================
import sys
from urllib import urlopen
from BeautifulSoup import BeautifulSoup, SoupStrainer
import re
from Queue import Queue, Empty
from threading import Thread
W_STOP = 1
class Worker(Thread):
"""Thread executing tasks from a given tasks queue"""
def __init__(self, pool, tasks):
Thread.__init__(self)
self.tasks = tasks
self.daemon = True
self.pool = pool
self.state = None
self.start()
def stop(self):
self.state = W_STOP
def run(self):
while True:
if self.state == W_STOP:
print "\ncalled stop"
break
try:
func, args, kargs = self.tasks.get(timeout=3)
except Empty:
continue
print "\n***START*** %s" % str(self)
try:
func(*args, **kargs)
except Exception, e:
print e
print "\n***STOP*** %s", str(self)
self.tasks.task_done()
class ThreadPool:
"""Pool of threads consuming tasks from a queue"""
def __init__(self, num_threads):
#self.tasks = Queue(num_threads)
self.tasks = Queue()
self.workers = []
for _ in range(num_threads):
self.workers.append(Worker(self,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()
def stop_threads(self):
for w in self.workers:
w.stop()
def wait_stop(self):
self.wait_completion()
self.stop_threads()
visited = set()
queue = Queue()
external_links_set = set()
internal_links_set = set()
external_links = 0
def process(pool,host,url):
try:
content = urlopen(url).read()
except UnicodeDecodeError:
return
for link in BeautifulSoup(content, parseOnlyThese=SoupStrainer('a')):
try:
href = link['href']
except KeyError:
continue
if not href.startswith('http://'):
href = 'http://%s%s' % (host, href)
if not href.startswith('http://%s%s' % (host, '/')):
continue
internal_links_set.add(href)
if href not in visited:
visited.add(href)
pool.add_task(process,pool,host,href)
else:
pass
def start(host,charset):
pool = ThreadPool(20)
pool.add_task(process,pool,host,'http://%s/' % (host))
pool.wait_stop()
start('evgenm.com','utf8')
答案 0 :(得分:1)
您正在线程之间共享状态(即在is_all_wait
中),而不进行同步。此外,所有线程都在“等待”的事实并不是队列为空的可靠指示(例如,他们都可能正在完成任务)。我怀疑,在队列真正为空之前,线程偶尔会退出。如果这种情况经常发生,您将在队列中留下任务但没有线程来运行它们。所以queue.join()
将永远等待。
我的推荐是:
is_all_wait
- 这不是一个可靠的指标state
- 这不是必要的queue.join
告知您处理所有内容的时间如果你需要杀死线程(例如,这是一个较大的,长期运行的程序的一部分),那么在queue.join()
后执行此操作。
答案 1 :(得分:0)
我有基本的python知识但是python中的线程并不是没用的?我看过很多文章批评全球锁定翻译。