PGF Service: limit the number of parallel calls to the C run-time parse function to 4 by default

The limit can be changed with the -j flag

src/compiler/GF/Interactive.hs

@@ -71,11 +71,12 @@ shell opts files = loop opts =<< runSIO (importInEnv emptyGFEnv opts files)
 -- | Run the GF Server (@gf -server@).
 -- The 'Int' argument is the port number for the HTTP service.
 mainServerGFI opts0 port files =
-    server port root (execute1 opts)
+    server jobs port root (execute1 opts)
       =<< runSIO (importInEnv emptyGFEnv opts files)
   where
     root = flag optDocumentRoot opts
     opts = beQuiet opts0
+    jobs = join (flag optJobs opts)
 #else
 mainServerGFI opts files =
   error "GF has not been compiled with server mode support"

src/compiler/GF/Server.hs

@@ -56,10 +56,10 @@ import URLEncoding(decodeQuery)
 debug s = logPutStrLn s
 
 -- | Combined FastCGI and HTTP server
-server port optroot execute1 state0 =
+server jobs port optroot execute1 state0 =
   do --stderrToFile logFile
      state <- newMVar M.empty
-     cache <- PS.newPGFCache
+     cache <- PS.newPGFCache jobs
      datadir <- getDataDir
      let root = maybe (datadir</>"www") id optroot
 --   debug $ "document root="++root