I’m trying to use xmlrpc client from many QThreads. To make sure that only one thread is using xmlrpc client I created lock with QMutex. My code:
import sys
import xmlrpclib
import threading
import time
from SimpleXMLRPCServer import SimpleXMLRPCServer
from PyQt4 import QtCore, QtGui
class MM(object):
def __init__(self):
self.lock = QtCore.QMutex()
self.xmlrpc_client = xmlrpclib.ServerProxy('http://localhost:9092')
def __getattr__(self, name):
self.lock.lock()
sys.stderr.write('locked, for %s\n' % name)
print threading.current_thread()
result = self.xmlrpc_client.__getattr__(name)
sys.stderr.write('unlocked by %s\n' % name)
self.lock.unlock()
return result
class Server(QtCore.QThread):
def __init__(self):
QtCore.QThread.__init__(self)
self.server = None
def run(self):
self.server = SimpleXMLRPCServer(("localhost", 9092), logRequests = False)
def one():
return 1
self.server.register_function(one, 'one')
self.server.serve_forever()
print "SERVER DONE"
class Ask(QtCore.QThread):
def __init__(self, mmInst):
QtCore.QThread.__init__(self)
self.mm = mmInst
self._stopping = False
def run(self):
while not self._stopping:
time.sleep(0.5)
print self.mm.one()
def stop(self):
self._stopping = True
self.wait()
def start_gui():
app = QtGui.QApplication(sys.argv)
server = Server()
server.start()
time.sleep(1)
mm = MM()
print mm.one()
a1 = Ask(mm)
a1.start()
a2 = Ask(mm)
a2.start()
try:
app.exec_()
except KeyboardInterrupt:
server.server.shutdown()
if __name__ == "__main__":
start_gui()
But it doesn’t work and I’m not sure why. Here is output:
locked, for one
<_MainThread(MainThread, started 1648)>
unlocked by one
1
locked, for one
<_DummyThread(Dummy-1, started daemon 356)>
unlocked by one
locked, for one
<_DummyThread(Dummy-2, started daemon 1480)>
unlocked by one
Traceback (most recent call last):
File "H:\poker\repos\TestSuite\test.py", line 46, in run
print self.mm.one()
File "C:\Python27\lib\xmlrpclib.py", line 1224, in __call__
return self.__send(self.__name, args)
File "C:\Python27\lib\xmlrpclib.py", line 1575, in __request
verbose=self.__verbose
File "C:\Python27\lib\xmlrpclib.py", line 1264, in request
return self.single_request(host, handler, request_body, verbose)
File "C:\Python27\lib\xmlrpclib.py", line 1289, in single_request
self.send_request(h, handler, request_body)
File "C:\Python27\lib\xmlrpclib.py", line 1391, in send_request
connection.putrequest("POST", handler, skip_accept_encoding=True)
File "C:\Python27\lib\httplib.py", line 853, in putrequest
raise CannotSendRequest()
httplib.CannotSendRequest
Traceback (most recent call last):
File "H:\poker\repos\TestSuite\test.py", line 46, in run
print self.mm.one()
File "C:\Python27\lib\xmlrpclib.py", line 1224, in __call__
return self.__send(self.__name, args)
File "C:\Python27\lib\xmlrpclib.py", line 1575, in __request
verbose=self.__verbose
File "C:\Python27\lib\xmlrpclib.py", line 1264, in request
return self.single_request(host, handler, request_body, verbose)
File "C:\Python27\lib\xmlrpclib.py", line 1294, in single_request
response = h.getresponse(buffering=True)
File "C:\Python27\lib\httplib.py", line 1015, in getresponse
raise ResponseNotReady()
httplib.ResponseNotReady
When using only one Thread works fine:
$ diff -u test.py.back test.py
--- test.py.back 2012-03-14 01:34:37.666425000 +0100
+++ test.py 2012-03-14 01:33:01.423265000 +0100
@@ -63,8 +63,8 @@
a1 = Ask(mm)
a1.start()
- a2 = Ask(mm)
- a2.start()
+ #a2 = Ask(mm)
+ #a2.start()
try:
app.exec_()
$ python test.py
locked, for one
<_MainThread(MainThread, started -1219930432)>
unlocked by one
1
locked, for one
<_DummyThread(Dummy-1, started daemon -1287918736)>
unlocked by one
1
locked, for one
<_DummyThread(Dummy-1, started daemon -1287918736)>
unlocked by one
1
locked, for one
<_DummyThread(Dummy-1, started daemon -1287918736)>
unlocked by one
1
When using two different instances of MM also works fine:
$ diff -u test.py.back test.py
--- test.py.back 2012-03-14 01:34:37.666425000 +0100
+++ test.py 2012-03-14 01:38:47.352862000 +0100
@@ -57,13 +57,13 @@
time.sleep(1)
- mm = MM()
- print mm.one()
+ #mm = MM()
+ #print mm.one()
- a1 = Ask(mm)
+ a1 = Ask(MM())
a1.start()
- a2 = Ask(mm)
+ a2 = Ask(MM())
a2.start()
try:
adam@sabayon /media/Nowy/poker/repos/TestSuite $ python test.py
locked, for one
locked, for one
<_DummyThread(Dummy-1, started daemon -1288275088)><_DummyThread(Dummy-2, started daemon -1298138256)>
unlocked by one
unlocked by one
11
locked, for one
<_DummyThread(Dummy-2, started daemon -1298138256)>
unlocked by one
locked, for one
<_DummyThread(Dummy-1, started daemon -1288275088)>
unlocked by one
1
1
locked, for one
<_DummyThread(Dummy-1, started daemon -1288275088)>
unlocked by one
locked, for one
1<_DummyThread(Dummy-2, started daemon -1298138256)>
unlocked by one
1
There were a couple problems that I saw with the code, but mainly the one that I was getting right away was that you were starting the client before the server was ready. When I instantiated the server first, then the client, I stopped getting connection errors.
I also removed your spinning while loop and instead just started the pyqt event loop. Also you werent really passing your MM instance to your Ask class (not that it mattered much for this example since you were using the same instance).
Anyways, here is my version that seems to function:
Update
After looking into this a bit more, I realized that its a bug in python 2.7 and xmlrpc, where they changed how it creates connections. http://bugs.python.org/issue6907
Strangely, this code does not crash for me on python 2.6/2.7 on OSX, or on python 2.6 under linux. But it DOES crash for me with python 2.7 under linux.
When I moved the locking mechanism outside of the MM instance, it seemed to start working under 2.7 on linux: