I support acceptance here, it'll be great to land this so -jsem can be used more reliably. Adam On 23/03/2026 11:25, Simon Marlow wrote:
wz1000 submitted proposal #673: Update jsem proposal to address problems discovered in GHC #25087 <https://github.com/ghc-proposals/ghc- proposals/pull/673>
The proposal is an update to the `-jsem` mechanism for sharing compute resources between Cabal/stack and GHC, which was previously accepted as proposal #540.
In summary #673 fixes an issue with #540: the specified implementation had a potential for runtime crashes due to dependence on the representation of a runtime shared data structure (the system semaphore).
The technical fix is to provide a protocol layer to abstract away from the representation. This is an implementation detail though; the problem with the proposal is that it *overspecified the implementation*. The fix is to avoid doing that, and introduce a mechanism for versioning the protocol to allow for future changes.
As shepherd I'm recommending acceptance.
-- Adam Gundry, Haskell Consultant Well-Typed LLP, https://www.well-typed.com/ Registered in England & Wales, OC335890 27 Old Gloucester Street, London WC1N 3AX, England