> Sure, except that if the server is to be used by multiple clients, you will > get clashes in the PIT when say two clients both try to compile a module > with the same name. > > The PIT is indexed by Module, which is basically the pair > (package,modulename), and the package for the main program is always the > same: "main". > > This will work fine if you spin up a new server for each program you want to > build - maybe that's fine for your use case?
Yep, I have a new server for each CPU. So compiling one program will start up (say) 4 compilers and one server. Then shake will start throwing source files at the server, in the proper dependency order, and the server will distribute the input files among the 4 servers. Each server is single-threaded so I don't have to worry about calling GHC functions reentrantly. But --make is single-threaded as well, so why doesn't it just call compileFile repeatedly and instead bother with all that HPT stuff? Is it just for ghci? >> The 'user' is low for the server because it doesn't count time spent >> by the subprocesses on the other end of the socket, but excluding >> linking it looks like I can shave about 25% off compile time. >> Unfortunately it winds up being just about the same as ghc --make, so >> it seems too low. > > But that's what you expect, isn't it? It's surprising to me that the serial --make is just about the same speed as a parallelized one. The whole point was to compile faster! Granted, each interface has to be loaded for each processor while --make only needs to do it once, but once loaded they should stay loaded and I'd expect the benefit from two processors would win out pretty quickly. > --make has a slight advantage for linking in that it knows which packages it > needs to link against, whereas plain ghc will link against all the packages > on the command line. Ohh, so maybe with --make it can omit some packages and do less work. Let me try minimizing the -packages and see if that helps. As an aside, it would be handy to be able to ask ghc "given this main module, which -packages should the final program get?" but not actually compile anything. Is there a way to do that, short of writing my own with the ghc api? Would it be a reasonable ghc flag, along the lines of -M but for packages? BTW, in case anyone is interested, a darcs repo is at http://ofb.net/~elaforge/ghc-server/ _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
