StablePtr / StableName ?

Simon Marlow marlowsd at
Tue Jan 24 09:38:16 UTC 2017

StableNames do use the RTS hash table implementation, but StablePtr does
*not*, the ticket is incorrect.  But to be clear, nothing has changed -
StableName has always used this hash table implementation.  No doubt it
could be faster if we used a better hash table, but whether it matters to
you or not depends on what else your application is doing - is StableName
in the inner loop? You'd have to measure it.


On 22 January 2017 at 16:09, Johannes Waldmann <
johannes.waldmann at> wrote:

> Dear ghc devs,
> would the StablePtr performance issue (slow hash table)
> also affect StableNames?
> Cf.
> Could making 10^5 stable names, and accessing each just once,
> take noticeable time? Where would this show up in a profile?
> I guess there's no easy way to change the ersatz library
> (StableName this is the fundamental mechanism for detecting sharing)
> but if these issues are related, then ersatz provides a
> performance test case.
> Thanks, Johannes.
> _______________________________________________
> ghc-devs mailing list
> ghc-devs at
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