Question

I have a python script that is a http-server: http://paste2.org/p/89701, when benchmarking it against ApacheBench (ab) with a concurrency level (-c switch) that is lower then or equal to the value i specified in the socket.listen()-call in the sourcecode everything works fine, but as soon as put the concurrency level in apache bench above the value in the socket.listen()-call performance drops through the floor, some example:

• socket.listen(10) and ab -n 50 -c 10 http://localhost/ = 1200req/s
• socket.listen(10) and ab -n 50 -c 11 http://localhost/ = 40req/s
• socket.listen(100) and ab -n 5000 -c 100 http://localhost/ = 1000req/s
• socket.listen(100) and ab -n 5000 -c 101 http://localhost/ = 32req/s

Nothing changes in the code between the two calls, I can’t figure out what is wrong – been at this problem for one day now. Also note that: The multiplexing version of the same code (I wrote to compare to the threaded version) works FINE no matter what socket.listen() is set to or what the concurrency (-c switch) in apache is set to.

I’ve spent a day on IRC/python docs, posted on comp.lang.python and on my blog – I can’t find ANYONE that even has an idea what could be wrong. Help me!

Answer 1

I cannot confirm your results, and your server is coded fishy. I whipped up my own server and do not have this problem either. Let’s move the discussion to a simpler level:

import thread, socket, Queue  connections = Queue.Queue() num_threads = 10 backlog = 10  def request():     while 1:         conn = connections.get()         data = ''         while '\r\n\r\n' not in data:             data += conn.recv(4048)         conn.sendall('HTTP/1.1 200 OK\r\n\r\nHello World')         conn.close()  if __name__ == '__main__':     for _ in range(num_threads):         thread.start_new_thread(request, ())      acceptor = socket.socket(socket.AF_INET, socket.SOCK_STREAM)     acceptor.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)     acceptor.bind(('', 1234))     acceptor.listen(backlog)     while 1:         conn, addr = acceptor.accept()         connections.put(conn) 

which on my machine does:

ab -n 10000 -c 10 http://127.0.0.1:1234/ --> 8695.03 [#/sec] ab -n 10000 -c 11 http://127.0.0.1:1234/ --> 8529.41 [#/sec]