Thread-safe GHC

Corentin Dupont at
Mon Aug 31 13:18:15 UTC 2015

I am wondering if GHC itself is thread-safe.
I am using Hint, and it reports that GHC is not thread-safe, and that I
can't safely run two instances of the interpreter simultaneously.
Is that still the case?

---------- Forwarded message ----------
From: Daniel Gorín <jcpetruzza at>
Date: Thu, Aug 27, 2015 at 5:09 PM
Subject: Re: Thread-safe Hint
To: Corentin Dupont < at>

Hi Corentin,

sorry for the late reply. Until relatively recently, the problem was still
on. But I too remember seeing something related to this issue being fixed
(iirc, the problem was the runtime linker, which used global state), so
perhaps it is already fixed in 7.10. If you can verify this, it shouldn’t
be hard to show the error message only on old versions of ghc. I’ll be away
for a couple of weeks, but if you want to look into this and send a patch,
I’ll merge it when I return.


> On 24 Aug 2015, at 10:43 am, Corentin Dupont < at>
> Hello Daniel,
> I noticed the following message in Hint:
> This version of GHC is not thread-safe,can't safely run two instances of
the interpreter simultaneously.
> Is it still the case with recent versions of GHC?
> It would be neat to be able to launch several instances of the
interpreter. In my game Nomyx I have several "match-up" going on and having
one instance of the interpreter would be nicer. Otherwise I am obliged to
reset the interpret each time I want to interpret something, which is time
consuming (2-3 seconds).
> Thanks,
> C
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the ghc-devs mailing list