Looking through the code and experimenting, using the 'Expect: 100-continue' header resulted in the desired behavior - having the response headers checked before the request body was streamed. Mark On Sun, Feb 28, 2016 at 2:20 PM, Mark Fine wrote:

I'm running into a problem handling requests with streaming request bodies that fail - using http-client, the failure takes a long time (potentially never) to propagate. Simple code (runnable project here https://github.com/mfine/streamy):

{-# LANGUAGE OverloadedStrings #-}

import Control.Monad import Data.Conduit.Combinators import Network.HTTP.Conduit import System.Environment

a :: IO () a = do manager <- newManager tlsManagerSettings request <- parseUrl "http://httpbin.org/status/409" void $ httpLbs request manager

b :: IO () b = do manager <- newManager tlsManagerSettings request <- parseUrl "http://httpbin.org/status/409" void $ flip httpLbs manager request { requestBody = requestBodySourceChunked $ repeatM $ return "a" }

Running "a" above works as expected (propagating the error immediately). Running "b" has variable results, mostly never propagating the error. Looking at the wire, I can see that the 409 status comes back, but the exception does not propagate.

Is there something I can do here to get quicker failure? Thanks!

Mark