On OSX, I can run two instances of my yesod app on the same port without error. The first "shadows" the second; the second starts receiving requests after the first terminates (simonmichael/hledger#226).
I can reproduce this with bindPortTCP:
#!/usr/bin/env stack
{- stack runghc --package network --package streaming-commons -}
{-# LANGUAGE OverloadedStrings #-}
import Data.Streaming.Network
import Network.Socket
main = do
let port = 5001
host = "*4"
-- host = "!4"
putStr "should pass: " >> bindPortTCP port host >>= print
putStr "should fail: " >> bindPortTCP port host >>= print -- doesn't fail on OSX. With host = "!4" it does
putStr "should fail: " >> bindPortTCP port host >>= printOn GNU/Linux, it fails when expected:
$ ./226-test.hs
should pass: <socket: 10>
should fail: 226-test.hs: bind: resource busy (Address already in use)
but on OSX, it doesn't fail until the third bind:
$ ./226-test.hs
should pass: <socket: 22>
should fail: <socket: 23>
should fail: 226-test.hs: bind: resource busy (Address already in use)
(I don't know about Windows.)
If I change the host preference from "*4" to "!4", it works as expected.
On OSX, I can run two instances of my yesod app on the same port without error. The first "shadows" the second; the second starts receiving requests after the first terminates (simonmichael/hledger#226).
I can reproduce this with bindPortTCP:
On GNU/Linux, it fails when expected:
but on OSX, it doesn't fail until the third bind:
(I don't know about Windows.)
If I change the host preference from "*4" to "!4", it works as expected.