Python SimpleHTTPServer running on a thread won't close port
I have the following code:
import os
from ghost import Ghost
import urlparse, urllib
import SimpleHTTPServer
import SocketServer
import sys, traceback
from threading import Thread, Event
from time import sleep
please_die = Event() # this is my enemy
httpd = None
PORT = 8001
address = 'http://localhost:'+str(PORT)+'/'
search_dir = './category'
def main():
"""
basic run script routine,
FIXME: is supossed to exits gracefully
"""
thread = Thread(target = simpleServe)
try:
thread.start()
run()
except KeyboardInterrupt:
print "Shutdown requested"
except Exception:
traceback.print_exc(file=sys.stdout)
shutdown()
sys.exit(0)
def shutdown():
global httpd
global please_die
print "Shutting down"
# A try - except for the shutdown routine
try:
please_die.wait() # how do you do?
httpd.shutdown() # Please! I whant to run you multiple times.
print "Have you died?"
except Exception:
traceback.print_exc(file=sys.stdout)
def path2url(path):
"""
constructs an url from a relative path / concatenates the global address
variable with the path given
"""
global address
return urlparse.urljoin(address, urllib.pathname2url(path))
def simpleServe():
global httpd, PORT
please_die.set() # Attaching the event to this thread
# Start the service
Handler = SimpleHTTPServer.SimpleHTTPRequestHandler
httpd = SocketServer.TCPServer(("", PORT), Handler)
print "serving at port", PORT
# And loop infinetly in the hope that I can stop you later
httpd.serve_forever()
def run():
global search_dir;
ghost = Ghost() # the webkit facade
with ghost.start() as session:
session.set_viewport_size(2560, 1600) # "retina" size
for directory, subdirectories, files in os.walk(search_dir):
for file in files:
path = os.path.join(directory, file)
urlPath = path2url(path)
process(session, urlPath);
def process(session, urlPath):
page, resources = session.open(urlPath)
assert page.http_status == 200
# ... other asserts here
if __name__ == '__main__':
main()
The idea is to create a script that starts a "simple HTTP server", makes some requests, and then exits.
The first time it starts up without problems:
...
127.0.0.1 - - [31/Jul/2015 13:16:17] "GET /category/52003.html HTTP/1.1" 200 -
127.0.0.1 - - [31/Jul/2015 13:16:17] "GET /category/52003.html HTTP/1.1" 200 -
127.0.0.1 - - [31/Jul/2015 13:16:17] "GET /category/52003.html HTTP/1.1" 200 -
127.0.0.1 - - [31/Jul/2015 13:16:17] "GET /static/img/glyphicons-halflings.png HTTP/1.1" 200 -
Shutting down
Have you died?
Running it a second time results in a crash in that:
The address is already in use
Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
self.run()
File "/usr/lib/python2.7/threading.py", line 763, in run
self.__target(*self.__args, **self.__kwargs)
File "download-images.py", line 51, in simpleServe
httpd = SocketServer.TCPServer(("", PORT), Handler)
File "/usr/lib/python2.7/SocketServer.py", line 420, in __init__
self.server_bind()
File "/usr/lib/python2.7/SocketServer.py", line 434, in server_bind
self.socket.bind(self.server_address)
File "/usr/lib/python2.7/socket.py", line 228, in meth
return getattr(self._sock,name)(*args)
error: [Errno 98] Address already in use
If I kill all python processes than the script starts up again, and because of this, I assume I was using this thread incorrectly, but cannot find where.
Update
Forgot to mention that
my OS:
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 15.04
Release: 15.04
Codename: vivid
The pit I am using is:
$ python --version
Python 2.7.9
$ netstat -putelan | grep 8001 prints:
$ netstat -putelan | grep 8001
(Not all processes could be identified, non-owned process info
cp 0 0 127.0.0.1:34691 127.0.0.1:8001 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:8001 127.0.0.1:34866 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:34798 127.0.0.1:8001 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:8001 127.0.0.1:34588 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:34647 127.0.0.1:8001 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:34915 127.0.0.1:8001 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:34674 127.0.0.1:8001 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:34451 127.0.0.1:8001 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:8001 127.0.0.1:34930 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:8001 127.0.0.1:34606 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:34505 127.0.0.1:8001 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:34717 127.0.0.1:8001 TIME_WAIT 0 0 -
tcp 0 0 127.0.0.1:8001 127.0.0.1:34670 0 0 127.0.0.1:8001 127.0.0.1:34626
...
I cannot post the whole sequence (from outside of post stackoverflow). The rest is the same with port 34 *** mixed with port 8001 in a uniform sequence.
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As @LFJ says, this is probably due to the attribute allow_reuse_address
TCPServer
.
httpd = SocketServer.TCPServer(("", PORT), Handler, bind_and_activate=False)
httpd.allow_reuse_address = True
try:
httpd.server_bind()
httpd.server_activate()
except:
httpd.server_close()
raise
Equivalent code:
SocketServer.TCPServer.allow_reuse_address = True
https = SocketServer.TCPServer(("", PORT), Handler)
Let's explain a little why.
When you include it TCPServer.allow_reuse_address
, it adds an option to the socket:
class TCPServer:
[...]
def server_bind(self):
if self.allow_reuse_address:
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
[...]
What is it socket.SO_REUSEADDR
?
This socket option tells the kernel that even if this port is busy (in
the TIME_WAIT state), go ahead and reuse it anyway. If it is busy,
but with another state, you will still get an address already in use
error. It is useful if your server has been shut down, and then
restarted right away while sockets are still active on its port. You
should be aware that if any unexpected data comes in, it may confuse
your server, but while this is possible, it is not likely.
In fact, it allows you to reuse the binding address of the socket socket. If another process tries to bind while the socket is not listening, the process will be allowed to use that socket bind address.
The reason you need to enable this is because you are not closing yours correctly TCPServer
. To close it correctly, you have to run a method shutdown
that will close the thread that was running server_forever
and then close the socket correctly by calling the method server_close
.
def shutdown():
global httpd
global please_die
print "Shutting down"
try:
please_die.wait() # how do you do?
httpd.shutdown() # Stop the serve_forever
httpd.server_close() # Close also the socket.
except Exception:
traceback.print_exc(file=sys.stdout)
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I saw the TCPServer source code:
def server_bind(self):
"""Called by constructor to bind the socket.
May be overridden.
"""
if self.allow_reuse_address:
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.socket.bind(self.server_address)
self.server_address = self.socket.getsockname()
allow_reuse_address must be set for binding. so try this:
SocketServer.TCPServer.allow_reuse_address=True
httpd = SocketServer.TCPServer(("", PORT), Handler)
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You do not clean up the server after it is closed. This means that you leave dead socket resources lying around that the OS does not clean up immediately after the process ends.
You need to call httpd.server_close()
the finally block after your call to httpd.serve_forever()
. This call tells the OS to release all resources that might have been associated with this server instance.
try:
httpd.serve_forever()
finally:
httpd.server_close()
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