RemoteException not re-thrown by pmap    12908 Closed samoconnor opened this Issue on Sep 1, 2015 · 6 comments Projects None yet Labels error handling parallel Milestone No milestone Assignees No one assigned 4 participants  samoconnor  simonster  malmaud  kshyatt Notifications    samoconnor samoconnor commented on Sep 1, 2015   everywhere function do_work i      r    1,2,3  i      println r      return r end  for r in pmap do_work,  3,2,1,0       println  pmap got result       println typeof r   end  The pmap   call above returns a RemoteException object in the result array instead of re-throwing it.  The output is:  . julia -p4 test-jl     From worker 3:  2     From worker 4:  1     From worker 2:  3 pmap got result Int64 pmap got result Int64 pmap got result Int64 pmap got result RemoteException  Changing pmap   to map   results in BoundsError as expected.  simonster The Julia Language member simonster commented on Sep 1, 2015  Related to dup of  7808. Also IMO err_stop true and rethrowing the error should be the default behavior for pmap.  kshyatt kshyatt added parallel error handling labels on Sep 1, 2015  samoconnor samoconnor commented on Sep 1, 2015  As far as I can tell err_stop true is just a performance optimisation to save time when an error occurs.  However, re-throwing the exception  after re-tries  seems like a must unless the documentation clearly says that pmap   returns exceptions in the output collection.  simonster The Julia Language member simonster commented on Sep 1, 2015  The problem is that there's no way to get the incomplete output of pmap if it throws an exception. If you set err_stop err_rety false, you clearly want the output even if it's incomplete.  With the defaults err_stop false, err_retry true it's a little less clear what you want.  The behavior should certainly be documented, but I imagine there are cases where it's desirable to return the exceptions instead of throwing them.  samoconnor samoconnor commented on Sep 3, 2015  To me it seems very clear: a function should either return a  complete  result or throw an exception. A function that returns exception objects in-line with an output collection seems odd to me.  If  incomplete output of pmap  is useful in some particular application, that application could just do:  pmap  1,2,3   do i     try          1,2  i      catch e         return e     end end   simonster The Julia Language member simonster commented on Sep 3, 2015  But then failures never get retried with err_retry true, because you don't throw an error.  samoconnor samoconnor referenced this issue on Sep 3, 2015   amitmurthy  propagate remote errors locally    5c30770  samoconnor samoconnor added a commit to samoconnor julia that referenced this issue on Sep 3, 2015   samoconnor  `pmap  ` cleanup. See  12908.    75b3c9a  samoconnor samoconnor added a commit to samoconnor julia that referenced this issue on Sep 3, 2015   samoconnor  `pmap  ` cleanup. See  12908.    d35ec03 This was referenced on Sep 3, 2015 Closed `pmap  ` cleanup. Fixes  12908.  12943 Closed pmap hides errors warnings  13224  malmaud malmaud commented on Oct 14, 2015  This is definitely an issue, but closing in favor of the earlier  7808.  malmaud malmaud closed this on Oct 14, 2015  multidis multidis referenced this issue in JuliaOpt Optim-jl on Nov 23, 2015 Closed Linesearch output in teh constrained branch  151