Python multiprocessing / Queue with cherrypy
Question
I am tying to do a python code with cherrypy. The objective is to call a script from UI and while the script generates the logs on console print it on the UI (Iframe / div). I am using CherryPy-3.2.4 and Python 2.7. Following is the sample code I have written which is refusing to work.
TestProcess.py
from multiprocessing import Process, Queue
import subprocess
import os, os.path
from string import Template
import cherrypy
from multiprocessing import Process, Queue
import HTML
import TestScript
class TestProcess(object):
PID=0
jquery_url = 'C:\CherryPy\TestScripts\jquery\jquery-1.11.1.js'
q=Queue()
@cherrypy.expose
def index(self):
html = """\
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> Test Doc </TITLE>
<script type="text/javascript" src="/static/jq/jquery-1.11.1.js"></script>
</HEAD>
<BODY>
<BR/>
<h3>Test utility</h3>
<form id="ping_form" target="console_iframe" method="post" action="/f">
<button id="ping" type="submit">Upgrade Installed Releases</button>
</form>
<BR/>
<iframe name="console_iframe" frameborder="1" width="1200"/>
</BODY>
</HTML>
"""
t = Template(html)
page = t.substitute(jquery_url=self.jquery_url)
return page
def f1():
print "*********** TEST **********************"
q.put([42, None, 'hello'])
@cherrypy.expose
def f(self, **kw):
q=Queue()
ts = TestScript.TestScript()
p = Process(target=ts.testCallFunction, args=(q,))
p.start()
#print q.get() # prints "[42, None, 'hello']"
p.join()
print "Test F"
def run_command():
# The yeilds here are the key to keeping things streaming
yield '<style>body {font-family: monospace;}</style>'
while(p.is_alive()):
while(not q.empty()):
yield q.get_nowait()
while(not q.empty()):
yield q.get_nowait()
return run_command()
if __name__ == '__main__':
conf = {
'/': {
'tools.sessions.on': True,
'tools.staticdir.root': os.path.abspath(os.getcwd())
},
'/static': {
'tools.staticdir.on': True,
'tools.staticdir.dir': './public'
}
}
q = Queue()
cherrypy.server.socket_host = '10.49.69.103'
cherrypy.config.update({
'log.screen':True,
'tools.sessions.on': True,
'checker.on':False
})
cherrypy.tree.mount(TestProcess(), config=None)
cherrypy.engine.start()
cherrypy.engine.block()
#cherrypy.quickstart(TestProcess(), '/', conf)
Class TestScript
class TestScript(object):
q=Queue()
def write_queue(self,data):
print "*********** TEST **********************"
scroll_to_bottom = '<script type="text/javascript">window.scrollBy(0,50);</script>'
if data == '\n':
self.q.put("\n<br />%s" % scroll_to_bottom) # include the iframe scroll fix
else:
self.q.put(data)
def testCallFunction(self, q):
#proc = subprocess.Popen(['python','CreateLog.py'],stdout=subprocess.PIPE)
cmd = subprocess.Popen(['python','CreateLog.py'], shell=True, stdout=subprocess.PIPE)
while True:
data = cmd.stdout.read(1) # Alternatively proc.stdout.read(1024)
if len(data) == 0:
break
self.write_queue(data) # sys.stdout.buffer.write(data) on Python 3.x
#print "*********** TEST **********************"
script CreateLog.py
#filters output
import time
i = 0
while (i<=10):
print hex(i)*512
i += 1
time.sleep(0.5)
Error That I get while running it
[24/Jul/2014:16:59:10] ENGINE Bus STARTING
[24/Jul/2014:16:59:10] ENGINE Started monitor thread 'Autoreloader'.
[24/Jul/2014:16:59:10] ENGINE Started monitor thread '_TimeoutMonitor'.
[24/Jul/2014:16:59:15] ENGINE Error in 'start' listener <bound method Server.sta
rt of <cherrypy._cpserver.Server object at 0x01583390>>
Traceback (most recent call last):
File "c:\Python27\lib\site-packages\cherrypy\process\wspbus.py", line 197, in
publish
output.append(listener(*args, **kwargs))
File "c:\Python27\lib\site-packages\cherrypy\_cpserver.py", line 151, in start
ServerAdapter.start(self)
File "c:\Python27\lib\site-packages\cherrypy\process\servers.py", line 168, in
start
wait_for_free_port(*self.bind_addr)
File "c:\Python27\lib\site-packages\cherrypy\process\servers.py", line 412, in
wait_for_free_port
raise IOError("Port %r not free on %r" % (port, host))
IOError: Port 8080 not free on '10.49.69.103'
[24/Jul/2014:16:59:15] ENGINE Shutting down due to error in start listener:
Traceback (most recent call last):
File "c:\Python27\lib\site-packages\cherrypy\process\wspbus.py", line 235, in
start
self.publish('start')
File "c:\Python27\lib\site-packages\cherrypy\process\wspbus.py", line 215, in
publish
raise exc
ChannelFailures: IOError("Port 8080 not free on '10.49.69.103'",)
What am I doing wrong ?
2 answers
solution1
1 2014-07-28 19:40:11
Make sure that the main module can be safely imported by a new Python interpreter without causing unintended side effects (such a starting a new process).
You did not protect the last lines of TestProcess.py with if __name__ == '__main__': , so the Process attempts to run another server.
solution2
0 2014-07-25 01:19:28
Port 8080 is not free, so the HTTP server can't listen on it. Try netstat -anpt to see what's using that port, or try "server.socket_port: 8081" or some other port that is free.
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