Groups   118 of 99+      julia-users ›  WARNING: replacing module  when invoking function with  everywhere - but module not available otherwise 3 posts by 2 authors      Adrian Salceanu    Sep 9   Hi,   I'm fumbling around with a little script with the end goal of running HttpServer handlers on multiple ports, in parallel, with each handler on a separate worker.   The code looks like this:     parallel_http-jl using HttpServer   function serve port::Int    http   HttpHandler   do req::Request, res::Response       Dates.now   |  string   end     server   Server http    run server, port  end   function run_in_parallel     servers   Vector RemoteRef      for w in workers       println  About to start server on $ 8000 + w        push! servers,  spawn serve 8000 + w     end     servers end   And in the REPL, running with julia -p 2:   julia   everywhere include  parallel_http-jl   WARNING: replacing module HttpServer WARNING: Method definition write Base.IO, HttpCommon.Response  in module HttpServer at  Users adrian .julia v0.4 HttpServer src HttpServer-jl:178 overwritten in module HttpServer at  Users adrian .julia v0.4 HttpServer src HttpServer-jl:178. WARNING: replacing module HttpServer WARNING: Method definition write Base.IO, HttpCommon.Response  in module HttpServer at  Users adrian .julia v0.4 HttpServer src HttpServer-jl:178 overwritten in module HttpServer at  Users adrian .julia v0.4 HttpServer src HttpServer-jl:178.   julia  servers   run_in_parallel   About to start server on 8002 About to start server on 8003 2-element Array RemoteRef T :AbstractChannel ,1 :   From worker 3: Listening on 0.0.0.0:8003...  From worker 2: Listening on 0.0.0.0:8002... RemoteRef Channel Any   2,1,17   RemoteRef Channel Any   3,1,18    The WARNING seems to imply that I'm doing something wrong - but if I don't run  using  on each worker, to avoid the warning, the module is not available to the worker. Am i missing something? Is there a better way to do this? Thanks!       Patrick Belliveau    Sep 9   Hi,      Running your code effectively executes   everywhere using HttpServer  This is known to generate those method redefinition warnings. The behaviour of using in a parallel environment is a known unresolved bug. It seems like the best syntax to use right now is  import HttpServer  Executed only on master process  everywhere using HttpServer  For a more detailed discussion and links to the relevant issues on github see this thread.      Adrian Salceanu    Sep 9   Thanks for the info and for the link, it's a good read. I wonder if anybody else has run into the issues Tim Holy mentions, with  everywhere using X.   Cheers!