On Tue, Mar 08, 2011 at 04:47:38PM -0500, Todd Willey wrote: > With this switch to python, does it make sense to revisit the concept > of openstack-common for things like logging, flag parsing, etc? What > components would you like to just be able to drop in from nova, > glance, or swift?
Yes, I'm planning on putting as much as possible into openstack-common, picking the best from nova/swift/glance as we move along. Nova, swift, and glance can start using those modules as they see fit. -Eric > > -todd[1] > > On Tue, Mar 8, 2011 at 4:05 PM, Eric Day <e...@oddments.org> wrote: > > Hi everyone, > > > > I added a sqlite backend to the prototype and ran some tests. Initially > > things were very slow, but after some further testing I was able > > to figure out where the time was being spent. In order to do this I > > added a very simple binary protocol interface to insert only. These > > tests are with a single server process and multiple client processes > > (so don't compare to previous email numbers that were two process). The > > numbers given are requests/second. > > > > echo (no parsing) - 17k > > > > binary - 13k > > binary+insert msg into dict - 11k > > binary+insert msg into sqlite - 8.7k > > > > wsgi - 4.9k > > wsgi+webob - 3.5k > > wsgi+webob+insert msg into dict - 3.4k > > wsgi+webob+insert msg into sqlite - 2.8k > > > > wsgi+webob+routes - 1.9k > > wsgi+webob+routes+insert msg into dict - 1.8k > > wsgi+webob+routes+insert msg into sqlite - 1.5k > > > > This shows that without wsgi/webob/routes, the performance is pretty > > decent). This would be the case when using an efficient binary protocol > > or perhaps a more efficient HTTP parser. > > > > Next, it shows WSGI adds significant overhead. The webob and routes > > modules also add a fair amount. > > > > I'm going to rework the current code in the prototype into a proper > > project in the burrow trunk with modular front-ends and back-ends so > > we can easily test new options. I'll stick with the current wsgi code > > for now just to get things functioning and we can look at optimizing > > later. For the proxy-server communication, we'll definitely need to > > use something more efficient than stock wsgi modules in the long run. > > > > No red flags yet with Python, and we're in the ballpark for efficiency > > with a binary protocol. A quick test with other servers showed > > rabbitmq at about 9k messages/sec (binary protocol, Erlang server) > > and Gearman at about 13k messages/sec (binary protocol, C server). > > > > -Eric > > > > On Mon, Mar 07, 2011 at 01:32:55PM -0800, Eric Day wrote: > >> I ran the tests again to verify: > >> > >> 500k requests - 10 processes each running 50k requests. > >> > >> time req/s cs us sy id > >> 2 thread/proc > >> echo c++ 7.19 69541 142182 23 77 0 > >> echo erlang 9.53 52465 105871 39 61 0 > >> echo python 9.58 52192 108420 42 58 0 > >> 2 thread/proc > >> wsgi python 58.74 8512 18132 86 14 0 > >> webob python 78.75 6349 13678 89 11 0 > >> webmachine* 63.50 7874 11834 89 11 0 > >> openstack 20.48 24414 49897 68 32 0 > >> > >> cs/us/sys/id are from vmstat while running the tests. > >> > >> * webmachine degrades over time with long-lived, multi-request > >> connections. This number was estimated with 1000 requests per > >> connection. At 50k requests per connection, the rate dropped to > >> 2582 req/s. > >> > >> As you can see I was able to reproduce the same numbers. If > >> anyone would like to do the same, you can grab lp:burrow for the > >> "openstack" Erlang application (compile and run ./start), webmachine > >> is at https://github.com/basho/webmachine (you need to create a demo > >> app and make sure you set nodelay for the socket options), and I've > >> attached the python server and client (start 10 client processes when > >> testing). Find me on irc (eday in #openstack) if you have questions. > >> > >> If we hit performance issues with this type of application, we'll > >> probably hit them around the same time with both Erlang and Python > >> (then we'll look to C/C++). Since most OpenStack developers are a lot > >> more comfortable with Python, I suggest we make the switch. Please > >> response with thoughts on this. I'll add a sqlite backend to the > >> Python prototype and run some performance tests against that to see > >> if any red flags come up. > >> > >> -Eric > >> > >> On Sat, Mar 05, 2011 at 10:39:18PM -0700, ksan...@doubleclix.net wrote: > >> > Eric, > >> > Thanks for your experimentation and analysis. Somewhat illustrates > >> > the > >> > point about premature optimization. First cut, have to agree with you > >> > and > >> > conclude that python implementation is effective, overall. As you > >> > said,if > >> > we find performance bottlenecks, especially as the payload size > >> > increases > >> > (as well as if we require any complex processing at the http server > >> > layer) > >> > we can optimize specific areas. > >> > Just for sure, might be better for someone else to recheck. That > >> > way > >> > we have done our due diligence. > >> > Cheers > >> > <k/> > >> > > >> > -------- Original Message -------- > >> > Subject: [Openstack] Queue Service Implementation Thoughts > >> > From: Eric Day <e...@oddments.org> > >> > Date: Sat, March 05, 2011 4:07 pm > >> > To: openstack@lists.launchpad.net > >> > > >> > Hi everyone, > >> > > >> > When deciding to move forward with Erlang, I first tried out the > >> > Erlang > >> > REST framework webmachine (it is built on top of mochiweb and used > >> > by projects like Riak). After some performance testing, I decided to > >> > write a simple wrapper over the HTTP packet parsing built into > >> > Erlang > >> > (also used by mochiweb/webmachine) to see if I could make things a > >> > bit more efficient. Here are the results: > >> > > >> > Erlang (2 threads) > >> > echo - 58823 reqs/sec > >> > webmachine - 7782 reqs/sec > >> > openstack - 24154 reqs/sec > >> > > >> > The test consists of four concurrent connections focused on packet > >> > parsing speed and framework overhead. A simple echo test was also > >> > done for a baseline (no parsing, just a simple recv/send loop). As > >> > you can see, the simple request/response wrapper I wrote did get > >> > some > >> > gains, although it's a little more hands-on to use (looks more like > >> > wsgi+webob in python). > >> > > >> > I decided to run the same tests against Python just for comparison. > >> > I > >> > ran echo, wsgi, and wsgi+webob decorators all using eventlet. I ran > >> > both single process and two process in order to compare with Erlang > >> > which was running with two threads. > >> > > >> > Python (eventlet) > >> > echo (1 proc) - 17857 reqs/sec > >> > echo (2 proc) - 52631 reqs/sec > >> > wsgi (1 proc) - 4859 reqs/sec > >> > wsgi (2 proc) - 8695 reqs/sec > >> > wsgi webob (1 proc) - 3430 reqs/sec > >> > wsgi webob (2 proc) - 6142 reqs/sec > >> > > >> > As you can see, the two process Python echo server was not too far > >> > behind the two thread Erlang echo server. The wsgi overhead was > >> > significant, especially with the webob decorators/objects. It was > >> > still on par with webmachine, but a factor of three less than my > >> > simple request/response wrapper. > >> > > >> > A multi-process python server does have the drawback of not being > >> > able to share resources between processes unless incurring the > >> > overhead of IPC. When thinking about a horizontally scalable > >> > service, > >> > where scaling-out is much more important than scaling-up, I think > >> > this becomes much less of a factor. Regardless of language choice, > >> > we will need a proxy to efficiently hash to a set of queue servers > >> > in > >> > any large deployment (or the clients will hash), but if that set is > >> > a > >> > larger number of single-process python servers (some running on the > >> > same machine) instead of a smaller number of multi-threaded Erlang > >> > servers, I don't think it will make too much of a difference (each > >> > proxy server will need to maintain more connections). In previous > >> > queue service threads I was much more concerned about this and was > >> > leaning away from Python, but I think I may be coming around. > >> > > >> > Another aspect I took a look at is options for message storage. For > >> > the fast, in-memory, unreliable queue type, here are some numbers > >> > for options in Python and Erlang: > >> > > >> > Raw message = key(16) + ttl(8) + hide(8) + body(100) = 132 bytes > >> > Python list/dict - 248 bytes/msg (88% overhead) > >> > Python sqlite3 - 168 bytes/msg (27% overhead) > >> > Erlang ets - 300 bytes/msg (127% overhead) > >> > > >> > The example raw message has no surrounding data structure, so it is > >> > obviously never possible to get down to 132 bytes. As the body > >> > grows, > >> > the overhead becomes less significant since they all grow the same > >> > amount. The best Python option is probably an in-memory sqlite > >> > table, > >> > which is also an option for disk-based storage as well. > >> > > >> > For Erlang, ets is really the only efficient in-memory option > >> > (mnesia > >> > is built on ets if you're thinking of that), and also has a disk > >> > counterpart called dets. The overhead was definitely more than I was > >> > expecting and is less memory efficient than both Python options. > >> > > >> > As we start looking at other stores to use, there are certainly more > >> > DB drivers available for Python than Erlang (due to the fact that > >> > Python is more popular). We'll want to push most of the heavy > >> > lifting > >> > to the pluggable databases, which makes the binding language less of > >> > a concern as well. > >> > > >> > So, in conclusion, and going against my previous opinion, I'm > >> > starting > >> > to feel that the performance gains of Erlang are really not that > >> > significant compared to Python for this style of application. If > >> > we're talking about a factor of three (and possibly less if we can > >> > optimize the wsgi driver or not use wsgi), and consider the database > >> > driver options for queue storage, Python doesn't look so bad. We'll > >> > certainly have more of a developer community too. > >> > > >> > We may still need to write parts in C/C++ if limits can't be > >> > overcome, > >> > but that would probably be the case for Erlang or Python. > >> > > >> > What do folks think? > >> > > >> > -Eric > >> > > >> > _______________________________________________ > >> > Mailing list: https://launchpad.net/~openstack > >> > Post to : openstack@lists.launchpad.net > >> > Unsubscribe : https://launchpad.net/~openstack > >> > More help : https://help.launchpad.net/ListHelp > > > >> import socket > >> import sys > >> > >> connection = socket.socket() > >> connection.connect(('localhost', int(sys.argv[1]))) > >> for x in xrange(50000): > >> connection.sendall("GET / HTTP/1.1\r\nHost: localhost\r\n\r\n") > >> connection.recv(1024) > > > >> import os > >> import sys > >> > >> import eventlet > >> import eventlet.wsgi > >> import webob.dec > >> import webob.exc > >> > >> COUNT = 0 > >> > >> def handle_echo(fd): > >> global COUNT > >> while True: > >> c = fd.recv(1024) > >> if not c: > >> break > >> fd.sendall(c) > >> COUNT += 1 > >> if COUNT % 1000 == 0: > >> sys.stderr.write('%d\n' % COUNT) > >> eventlet.sleep(0) > >> > >> def handle_wsgi(environ, start_response): > >> global COUNT > >> COUNT += 1 > >> if COUNT % 1000 == 0: > >> sys.stderr.write('%d\n' % COUNT) > >> eventlet.sleep(0) > >> start_response('200 Ok', [('Content-Type', 'text/plain')]) > >> return "test" > >> > >> @webob.dec.wsgify > >> def handle_webob(req): > >> global COUNT > >> COUNT += 1 > >> if COUNT % 1000 == 0: > >> sys.stderr.write('%d\n' % COUNT) > >> eventlet.sleep(0) > >> return webob.exc.HTTPOk(body="test") > >> > >> server = eventlet.listen(('localhost', int(sys.argv[2]))) > >> os.fork() > >> eventlet.hubs.use_hub('poll') > >> > >> if sys.argv[1] == 'echo': > >> while True: > >> new_sock, address = server.accept() > >> eventlet.spawn_n(handle_echo, new_sock) > >> # Add a slight delay between accepts so they balance between processes. > >> eventlet.sleep(0.010) > >> elif sys.argv[1] == 'wsgi': > >> eventlet.wsgi.server(server, handle_wsgi, log=sys.stdout) > >> elif sys.argv[1] == 'webob': > >> eventlet.wsgi.server(server, handle_webob, log=sys.stdout) > >> else: > >> print 'Usage: %s echo|wsgi|webob <port>' % sys.argv[0] > > > > > > _______________________________________________ > > Mailing list: https://launchpad.net/~openstack > > Post to : openstack@lists.launchpad.net > > Unsubscribe : https://launchpad.net/~openstack > > More help : https://help.launchpad.net/ListHelp > > _______________________________________________ Mailing list: https://launchpad.net/~openstack Post to : openstack@lists.launchpad.net Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp