Simple Servers
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Some example of simple web server designs using increasingly more sophisticated approaches. Requirements:
- Recent GHC
- Libraries: network, network-bytestring, event
Benchmarks with httperf,
$ httperf --server=localhost --port=5002 --uri=/ --num-conns=10000
Results
Basic concurrent server
Concurrent, with String IO:
import Network
import Control.Concurrent
import System.IO
main = withSocketsDo $ do
sock <- listenOn $ PortNumber 5002
loop sock
loop sock = do
(h,_,_) <- accept sock
forkIO $ body h
loop sock
where
body h = do
hPutStr h msg
hFlush h
hClose h
msg = "HTTP/1.0 200 OK\r\nContent-Length: 5\r\n\r\nPong!\r\n"
Measurements:
$ ghc -O2 --make A.hs
- Request rate: 6569.1 req/s (0.2 ms/req)
Concurrent, with network-bytestring
Now, using bytestring IO (via the network-bytestring package) (but still using the rts' select-based preemptive threads)
{-# LANGUAGE OverloadedStrings #-}
import Data.ByteString.Char8
import Network hiding (accept)
import Network.Socket
import Network.Socket.ByteString (sendAll)
import Control.Concurrent
main = withSocketsDo $ do
sock <- listenOn $ PortNumber 5002
loop sock
loop sock = do
(conn, _) <- accept sock
forkIO $ body conn
loop sock
where
body c = do sendAll c msg
sClose c
msg = "HTTP/1.0 200 OK\r\nContent-Length: 5\r\n\r\nPong!\r\n"
Measurements:
$ ghc -O2 --make H.hs
- Request rate: 9901.7 req/s (0.1 ms/req)
Epoll-based event callbacks
Now, instead of using the RTS' select mechanism to wake up threads, we use a custom epoll handler. Using epoll-based event handling, and bytestring IO:
{-# LANGUAGE OverloadedStrings #-}
-- A simple example of an epoll based http server in Haskell.
--
-- Uses two libraries:
-- * network-bytestring, bytestring-based socket IO.
-- - cabal install network-bytestring:
--
-- * haskell-event, epoll-based scalable IO events
-- - git clone git://github.com/tibbe/event.git
-- - autoreconf ; then cabal install
import Network hiding (accept)
import Network.Socket (fdSocket, accept)
import Network.Socket.ByteString
import Data.ByteString.Char8
import System.Event
import System.Posix
import System.Posix.IO
main = withSocketsDo $ do
sock <- listenOn $ PortNumber 5002
let fd = fromIntegral (fdSocket sock)
mgr <- new
registerFd mgr (client sock) fd evtRead
loop mgr
client sock _ _ = do
(c,_) <- accept sock
sendAll c msg
sClose c
msg = "HTTP/1.0 200 OK\r\nContent-Length: 5\r\n\r\nPong!\r\n"
Measurements:
ghc -O2 --make Epoll.hs
- Request rate: 15042.6 req/s (0.1 ms/req)
So significantly better.