Merge pull request #25 from neherlab/feat/emit-thread-errors

Errors occurring in threads are now passed to an error channel. The main thread is waiting on this channel. Upon creation of the root graph the error channel is closed, and the main thread continues the execution.

src/align.jl

@@ -640,7 +640,6 @@ function align(Gs::Graph...; compare=Mash.distance, energy=(hit)->(-Inf), minblo
     log("--> aligning pairs")
 
     events = Channel{Bool}(10);
-    result = Channel{Graph}(1);
 
     @spawn let
         while isopen(events)
@@ -649,6 +648,9 @@ function align(Gs::Graph...; compare=Mash.distance, energy=(hit)->(-Inf), minblo
         end
     end
 
+    error_channel = Channel(1)
+
+    G = nothing
     for clade ∈ postorder(tree)
         @spawn try
             if isleaf(clade)
@@ -667,16 +669,23 @@ function align(Gs::Graph...; compare=Mash.distance, energy=(hit)->(-Inf), minblo
                 if clade.parent !== nothing
                     put!(clade.parent.graph, G₀)
                 else
-                    put!(result, G₀); close(result)
+                    G = G₀
+                    close(error_channel)
                 end
             end
-        catch e
-            error(e)
+        catch err
+            put!(error_channel, [err, catch_backtrace()])
+            close(error_channel)
         end
     end
 
-    G = take!(result)
+    for (err, backtrace) in error_channel
+        @error "In-thread error during graph building:" exception=(err, backtrace)
+        error("graph construction failed, see above for stacktrace")
+    end
+
     close(events)
+
     return G
 end