我需要运行一次最多处理 3 个请求的服务器。我的设计是我有一个 TCP 服务器正在运行，并且将运行 3 个线程来处理这些请求。服务器将接受请求并将这些请求传递给使用锁的相应队列的线程。我也为队列设置了适当的锁。我的问题是，即使我有一个信号处理程序来在主进程必须退出时使用标志向线程发出信号。我不明白错误是什么，因为优雅退出没有按预期发生。输出如下：
vm:~/Desktop$ python multi_threaded_queueing.py
About to kickoff
About to kickoff
Starting Thread-1
About to kickoff
Starting Thread-2
Starting Thread-3
^CTraceback (most recent call last):
File "multi_threaded_queueing.py", line 94, in <module>
conn, addr = s.accept()
File "/usr/lib/python2.7/socket.py", line 202, in accept
sock, addr = self._sock.accept()
socket.error: [Errno 4] Interrupted system call
代码如下：
#!/usr/bin/python
import Queue
import threading
import time
import sys
import socket
import signal
HOST = '127.0.0.1'
PORT = 50007 # Arbitrary non-privileged port
s = None
exitFlag = 0
#signal handler for control C
def signal_handler(signal, frame):
print "Control+C has been pressed"
#setting the exit flag so that all the threads can get notified
exitFlag = 1
#wait till all the threads have finished processing and can gracefully exit
#I maintain an array for each thread to set the corresponding index when
#it has finished its processing. I and all the elements to see if its 0
#and based on which I will exit or wait
while 1:
num = 0
for ele in exitList:
num &= ele
if ele == 0:
sys.exit(0)
class myThread (threading.Thread):
#have a queue, thread ID and name for every thread.
def __init__(self, threadID, name, q):
threading.Thread.__init__(self)
self.threadID = threadID
self.name = name
self.q = q
def run(self):
print "Starting " + self.name
process_data(self.name, self.q, self.threadID)
print "Exiting " + self.name
def process_data(threadName, q, threadID):
#while exit flag is not set by the main thread keep processing the data
#present in the queue.
while not exitFlag:
queueLock[threadID].acquire()
if not workQueue[threadID].empty():
data = q[threadID].get()
queueLock[threadID].release()
print "%s processing %s" % (threadName, data)
else:
queueLock[threadID].release()
time.sleep(1)
exitThread[threadID] = 1
threadList = ["Thread-1", "Thread-2", "Thread-3"]
nameList = ["One", "Two", "Three", "Four", "Five"]
queueLock = []
workQueue = []
threads = []
threadID = 0
exitList = []
size = 3
request = 0
signal.signal(signal.SIGINT, signal_handler)
# Create new threads
#by default hard coding the number of threads to 3
for tName in threadList:
workQueue.append(Queue.Queue(10))
queueLock.append(threading.Lock())
exitList.append(0)
thread = myThread(threadID, tName, workQueue)
print "About to kickoff"
thread.start()
threads.append(thread)
threadID += 1
for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM, 0, socket.AI_PASSIVE):
af, socktype, proto, canonname, sa = res
try:
socket.setdefaulttimeout(10)
s = socket.socket(af, socktype, proto)
except socket.error, msg:
s = None
continue
try:
s.bind(sa)
s.listen(1)
except socket.error, msg:
s.close()
s = None
continue
break
if s is None:
print 'could not open socket'
sys.exit(1)
while 1:
conn, addr = s.accept()
print 'Connected by', addr
request += 1
#round robin scheduling for each thread
thread_index = request % size
while 1:
data = conn.recv(1024)
if not data: break
# Fill the queue with the request received
queueLock[thread_index].acquire()
for word in nameList:
workQueue[thread_index].put(word)
queueLock[thread_index].release()
# Wait for queue to empty
while not workQueue[thread_index].empty():
pass
conn.send(data)
conn.close()
# Notify threads it's time to exit
exitFlag = 1
print "setting the exitFlag"
# Wait for all threads to complete
for t in threads:
t.join()
print "Exiting Main Thread"