Hotfix bound threads for workers unsafe calls for llvm #4081
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When using foreign libraries that use thread-local state, a program must ensure that foreign calls are always made from the same OS thread, by way of making these calls in _bound threads_, see https://downloads.haskell.org/ghc/latest/docs/libraries/base-4.20.0.0-1f57/Control-Concurrent.html#g:8 This PR * adds a flag to the generic RPC server in `kore-rpc-types` to request running workers in bound threads. The server will use `forkOS` instead of `forkIO` in this case. * requests running with bound threads when an LLVM backend library is used. This _should_ protect us against problems related to using thread-local storage in the LLVM backend. Needs to be thoroughly tested before merging, because issues only materialised in proofs with substantial workload and parallel exploration.
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Fixes a problem with recently-introduced thread-local storage in the LLVM backend.
We have to make sure that all foreign calls relating to an LLVM-based term evaluation use the same OS thread, which can only be achieved via bound threads .
This PR
kore-rpc-typesto run request worker threads in bound threads (usingforkOS)kore-rpc-boosteruses this flag for bound threads when an LLVM backend library is usedunsafeto make executing OS threads block instead of having new OS threads created for concurrent Haskell execution (they won't read HS heap data and never call back into Haskell).This should protect us against problems related to using thread-local storage in the LLVM backend. Needs to be thoroughly tested before merging, because issues only materialised in proofs with substantial workload and parallel exploration.
PR #4080 uses
runInBoundThreadon the individual request processing calls instead of running the whole worker thread in the server as a bound thread. This was not solving the problem.