make -jN loops on Windows

Simon Peyton-Jones simonpj at
Thu Aug 29 11:30:41 CEST 2013

I was using integer-gmp. And sadly make -j2 locks up way before getting to integer-gmp.


From: Niklas Larsson [mailto:metaniklas at]
Sent: 28 August 2013 18:08
To: Simon Peyton-Jones
Cc: Kyle Van Berendonck; ghc-devs at
Subject: Re: make -jN loops on Windows


I have a hint of what could be wrong.

I looked through my configuration and saw that I used integer-simple. When I changed it to integer-gmp it blew up with -j4 (it didn't hang though, it errored out in the linking phase). The build went fine after I reran without -j.


2013/8/28 Simon Peyton-Jones <simonpj at<mailto:simonpj at>>
I tried make -j2, which locked up.  "sh validate" used -j but I'm not sure with what N.

It's tantalising if it worked for you!  And it worked fine on my old Win7 laptop.  Where did you get your mingw/msys installation from?  I got mine from, using the download installer "Mingw-get-setup.exe".

I have also just unravelled another bizarre failure, which I'll describe in a separate email.  Sadly resolving the latter does not fix the make -j2 problem.


From: ghc-devs [mailto:ghc-devs-bounces at<mailto:ghc-devs-bounces at>] On Behalf Of Niklas Larsson
Sent: 27 August 2013 23:56
To: Kyle Van Berendonck
Cc: ghc-devs at<mailto:ghc-devs at>
Subject: Re: make -jN loops on Windows


Are you using make -j with or without number of jobs? I tried with make -j4 on my Windows 8 machine and it worked well.


2013/8/27 Kyle Van Berendonck <kvanberendonck at<mailto:kvanberendonck at>>
Hi Simon,

I think this is a MinGW bug. If we're talking about the same bug (lockup, no console output, task manager shows cpu but it doesn't produce files, etc) I get it when building other projects with -j too and I don't think its GHC's fault.


Kyle Van Berendonck

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