Eventlet/Examples
Examples
These are short examples demonstrating the use of Eventlet. They are also included in the examples directory of the source.
echo server
This is a simple server that listens on port 6000 and simply echoes back every input line it receives. Connect to it with: telnet localhost 6000 Terminate your connection by quitting telnet (typically Ctrl-] and then 'quit')
<python>from eventlet import api
def handle_socket(client):
print "client connected"
fp = client.makefile()
while True:
# pass through every non-eof line
x = fp.readline()
if not x: break
fp.write(x)
print "echoed", x
print "client disconnected"
- server socket listening on port 6000
server = api.tcp_listener(('0.0.0.0', 6000)) while True:
new_sock, address = server.accept() # handle every new connection with a new coroutine api.spawn(handle_socket, new_sock)
server.close()</python>
web crawler
This is a simple web "crawler" that fetches a bunch of urls using a coroutine pool. It has as much concurrency (i.e. pages being fetched simultaneously) as coroutines in the pool.
<python>urls = ["http://www.google.com/intl/en_ALL/images/logo.gif",
"http://wiki.secondlife.com/w/images/secondlife.jpg", "http://us.i1.yimg.com/us.yimg.com/i/ww/beta/y3.gif"]
import time from eventlet import coros, httpc, util
- replace socket with a cooperative coroutine socket because httpc
- uses httplib, which uses socket. Removing this serializes the http
- requests, because the standard socket is blocking.
util.wrap_socket_with_coroutine_socket()
def fetch(url):
# we could do something interesting with the result, but this is # example code, so we'll just report that we did it print "%s fetching %s" % (time.asctime(), url) httpc.get(url) print "%s fetched %s" % (time.asctime(), url)
pool = coros.CoroutinePool(max_size=4) waiters = [] for url in urls:
waiters.append(pool.execute(fetch, url))
- wait for all the coroutines to come back before exiting the process
for waiter in waiters:
waiter.wait()</python>