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.

Cheers

Simon

On 22 January 2017 at 16:09, Johannes Waldmann <johannes.waldmann@htwk-leipzig.de> wrote:

Dear ghc devs,

would the StablePtr performance issue (slow hash table)
https://ghc.haskell.org/trac/ghc/ticket/13165
also affect StableNames?
Cf. https://github.com/ekmett/ersatz/issues/30

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.
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