set -N from the juvix global options

app/App.hs

@@ -248,7 +248,7 @@ runPipelineOptions m = do
   g <- askGlobalOptions
   let opt =
         defaultPipelineOptions
-          { _pipelineNumJobs = g ^. globalNumJobs,
+          { _pipelineNumThreads = g ^. globalNumThreads,
             _pipelineUseColors = not (g ^. globalNoColors)
           }
   runReader opt m

app/CommonOptions.hs

@@ -54,24 +54,24 @@ parseInputFiles exts' = do
 parseInputFile :: FileExt -> Parser (AppPath File)
 parseInputFile = parseInputFiles . NonEmpty.singleton
 
-numJobsOpt :: ReadM NumJobs
-numJobsOpt = eitherReader aux
+numThreadsOpt :: ReadM NumThreads
+numThreadsOpt = eitherReader aux
   where
-    aux :: String -> Either String NumJobs
+    aux :: String -> Either String NumThreads
     aux s = do
       i :: Int <- readEither s
-      mkNumJobs (Just i)
+      mkNumThreads (Just i)
 
-parseNumJobs :: Parser NumJobs
-parseNumJobs = do
+parseNumThreads :: Parser NumThreads
+parseNumThreads = do
   option
-    numJobsOpt
-    ( long "jobs"
-        <> short 'j'
+    numThreadsOpt
+    ( long "threads"
+        <> short 'N'
         <> metavar "JOBS"
-        <> value defaultNumJobs
+        <> value defaultNumThreads
         <> showDefault
-        <> help "Number of concurrent jobs to run"
+        <> help "Number of physical threads to run"
         <> completer (listCompleter [Juvix.show j | j <- [1 .. numCapabilities]])
     )
 

app/GlobalOptions.hs

@@ -24,7 +24,7 @@ data GlobalOptions = GlobalOptions
     _globalNoCoverage :: Bool,
     _globalNoStdlib :: Bool,
     _globalUnrollLimit :: Int,
-    _globalNumJobs :: NumJobs,
+    _globalNumThreads :: NumThreads,
     _globalFieldSize :: Maybe Natural,
     _globalOffline :: Bool
   }
@@ -58,7 +58,7 @@ defaultGlobalOptions :: GlobalOptions
 defaultGlobalOptions =
   GlobalOptions
     { _globalNoColors = False,
-      _globalNumJobs = defaultNumJobs,
+      _globalNumThreads = defaultNumThreads,
       _globalShowNameIds = False,
       _globalOnlyErrors = False,
       _globalNoTermination = False,
@@ -142,7 +142,7 @@ parseGlobalFlags = do
       ( long "show-name-ids"
           <> help "[DEV] Show the unique number of each identifier when pretty printing"
       )
-  _globalNumJobs <- parseNumJobs
+  _globalNumThreads <- parseNumThreads
   return GlobalOptions {..}
 
 parseBuildDir :: Mod OptionFields (Prepath Dir) -> Parser (AppPath Dir)

app/Main.hs

@@ -3,6 +3,7 @@ module Main (main) where
 import App
 import CommonOptions
 import Data.String.Interpolate (i)
+import GHC.Conc qualified as GHC
 import GlobalOptions
 import Juvix.Compiler.Pipeline.Root
 import TopCommand
@@ -13,6 +14,7 @@ main = do
   let parserPreferences = prefs showHelpOnEmpty
   invokeDir <- getCurrentDir
   (_runAppIOArgsGlobalOptions, cli) <- customExecParser parserPreferences descr
+  GHC.setNumCapabilities (numThreads (_runAppIOArgsGlobalOptions ^. globalNumThreads))
   mbuildDir <- mapM (prepathToAbsDir invokeDir) (_runAppIOArgsGlobalOptions ^? globalBuildDir . _Just . pathPath)
   mainFile <- topCommandInputPath cli
   mapM_ checkMainFile mainFile

package.yaml

@@ -179,7 +179,6 @@ executables:
       - polysemy == 1.9.*
     verbatim:
       default-language: GHC2021
-
   juvix:
     main: Main.hs
     source-dirs: app
@@ -193,6 +192,8 @@ executables:
       - string-interpolate == 0.3.*
     verbatim:
       default-language: GHC2021
+    ghc-options:
+      - -threaded
     when:
       - condition: flag(static)
         ld-options:

src/Juvix/Compiler/Pipeline/DriverParallel.hs

@@ -84,7 +84,7 @@ compileInParallel ::
        ]
       r
   ) =>
-  NumJobs ->
+  NumThreads ->
   Sem r ()
 compileInParallel nj = do
   t <- ask
@@ -95,7 +95,7 @@ compileInParallel nj = do
           { _compileArgsNodesIndex = idx,
             _compileArgsNodeName = getNodeName,
             _compileArgsDependencies = mkDependencies t,
-            _compileArgsNumWorkers = numJobs nj,
+            _compileArgsNumWorkers = numThreads nj,
             _compileArgsCompileNode = compileNode
           }
   void (compile args)
@@ -137,7 +137,7 @@ evalModuleInfoCache ::
        ]
       r
   ) =>
-  NumJobs ->
+  NumThreads ->
   Sem (ModuleInfoCache ': r) a ->
   Sem r a
 evalModuleInfoCache nj m = do

src/Juvix/Compiler/Pipeline/Options.hs

@@ -7,7 +7,7 @@ import Juvix.Prelude
 data PipelineOptions = PipelineOptions
   { _pipelineImportStrategy :: ImportScanStrategy,
     _pipelineDependenciesConfig :: DependenciesConfig,
-    _pipelineNumJobs :: NumJobs,
+    _pipelineNumThreads :: NumThreads,
     _pipelineUseColors :: Bool
   }
 
@@ -17,5 +17,5 @@ defaultPipelineOptions =
     { _pipelineImportStrategy = defaultImportScanStrategy,
       _pipelineDependenciesConfig = defaultDependenciesConfig,
       _pipelineUseColors = True,
-      _pipelineNumJobs = defaultNumJobs
+      _pipelineNumThreads = defaultNumThreads
     }

src/Juvix/Compiler/Pipeline/Run.hs

@@ -133,7 +133,7 @@ runIOEitherPipeline' entry a = do
     . runTopModuleNameChecker
     . runReader (opts ^. pipelineImportStrategy)
     . withImportTree (entry ^. entryPointModulePath)
-    . evalModuleInfoCacheHelper (opts ^. pipelineNumJobs)
+    . evalModuleInfoCacheHelper (opts ^. pipelineNumThreads)
     $ a
 
 evalModuleInfoCacheHelper ::
@@ -153,7 +153,7 @@ evalModuleInfoCacheHelper ::
        ]
       r
   ) =>
-  NumJobs ->
+  NumThreads ->
   Sem (ModuleInfoCache ': r) a ->
   Sem r a
 evalModuleInfoCacheHelper nj m = do
@@ -235,7 +235,7 @@ runReplPipelineIOEither' lockMode entry = do
       . runReader defaultImportScanStrategy
       . withImportTree (entry ^. entryPointModulePath)
       . ignoreProgressLog
-      . evalModuleInfoCacheHelper defaultNumJobs
+      . evalModuleInfoCacheHelper defaultNumThreads
       $ processFileToStoredCore entry
   return $ case eith of
     Left err -> Left err

src/Juvix/Data.hs

@@ -1,7 +1,7 @@
 module Juvix.Data
   ( module Juvix.Data.Effect,
     module Juvix.Data.Error,
-    module Juvix.Data.NumJobs,
+    module Juvix.Data.NumThreads,
     module Juvix.Data.Fixity,
     module Juvix.Data.FileExt,
     module Juvix.Data.Hole,
@@ -34,7 +34,7 @@ import Juvix.Data.Irrelevant
 import Juvix.Data.IsImplicit
 import Juvix.Data.Loc
 import Juvix.Data.NameId qualified
-import Juvix.Data.NumJobs
+import Juvix.Data.NumThreads
 import Juvix.Data.Pragmas
 import Juvix.Data.Processed
 import Juvix.Data.Uid

src/Juvix/Data/NumThreads.hs

@@ -0,0 +1,39 @@
+module Juvix.Data.NumThreads
+  ( NumThreads,
+    defaultNumThreads,
+    numThreadsOne,
+    numThreads,
+    mkNumThreads,
+    mkNumThreads',
+  )
+where
+
+import GHC.Conc
+import Juvix.Prelude.Base.Foundation
+import Prelude qualified
+
+-- | The number of jobs must be at least 1
+newtype NumThreads = NumThreads Int
+  deriving stock (Eq, Ord, Generic)
+
+instance Show NumThreads where
+  show (NumThreads i) = show i
+
+numThreadsOne :: NumThreads
+numThreadsOne = NumThreads 1
+
+numThreads :: NumThreads -> Int
+numThreads (NumThreads i) = i
+
+defaultNumThreads :: NumThreads
+defaultNumThreads = NumThreads (max 1 (numCapabilities - 2))
+
+mkNumThreads :: Maybe Int -> Either String NumThreads
+mkNumThreads = \case
+  Nothing -> Right defaultNumThreads
+  Just n
+    | n >= 1 -> return (NumThreads n)
+    | otherwise -> Left "The number of jobs cannot be negative"
+
+mkNumThreads' :: Maybe Int -> NumThreads
+mkNumThreads' = either (error . pack) id . mkNumThreads