Simple "Hello World" Warp-based web server crashes on Ubuntu x86_64

Anton Dessiatov anton.dessiatov at
Wed Mar 2 09:05:13 UTC 2016

Hello Ben,

I am bulding warp-3.2.2 with stack (lts-5.5 snapshot) using GHC 7.10.3. 
I have also created a ticket in GHC trac:

Hope this helps.


01.03.2016 21:53, Ben Gamari пишет:
> Антон Десятов <anton.dessiatov at> writes:
>> Hello dear GHC developers,
>> I have recently experienced what I believe to be a bug either in GHC or in
>> Warp library (if it is indeed in Warp then sorry for posting to wrong
>> mailing list). I've managed to shrink it to a few lines of code and publish
>> on a GitHub. Here is the link:
>> What I wanted to do is to establish network connection in my code and then
>> at some point pass it to Warp for further processing. What I got is that
>> after successfully processing first HTTP request my program consumes 100%
>> CPU and eventually crashes with an error like this:
>> *** Error in
>> `/home/farnsworth/work/warp-ghc-issue/.stack-work/install/x86_64-linux/lts-5.5/7.10.3/bin/warp-ghc-issue':
>> double free or corruption (!prev): 0x00000000016214b0 ***
>> Aborted (core dumped)
>> When compiled with -debug I see another message:
>> repro: internal error: ASSERTION FAILED: file rts/Schedule.h, line 137
>>      (GHC version 7.10.3 for x86_64_unknown_linux)
>>      Please report this as a GHC bug:
>> Aborted (core dumped)
>> I tried to debug it by enabling -dcore-lint and -debug in my
>> ~/.stack/config.yaml and what worries me is that in this case Warp itself
>> doesn't compile (tried with 7.10.2 and 7.10.3) giving core lint failure in
>> Network.Wai.Handler.Warp.HTTP2.Worker. Not sure if it is relevant, but
>> looks suspicious.
> This indeed quite relevant and concerning. Core lint issues should not
> occur; they mean that somehow GHC has taken correct code (it
> typechecked, afterall) and turned it into something horrible.
> That being said, I'm afraid I can't reproduce this issue locally. What
> warp version are you building against?
> In the meantime, could you open a bug on the GHC Trac for this issue? It
> would be quite helpful if you could attach the output from Core Lint
> when you do so.
> Cheers,
> - Ben

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