only finalize in the case that jl_current_exception is unset (#390)

* only finalize in the case that jl_current_exception is unset

* add tests

Co-authored-by: Simon Byrne <[email protected]>

Author: vchuravy

src/environment.jl

@@ -49,7 +49,15 @@ For more details, see [Finalizers](@ref).
 function refcount_dec()
     # refcount zero, all objects finalized, now finalize MPI
     if Threads.atomic_sub!(REFCOUNT, 1) == 1
-        !Finalized() && _Finalize()
+        if !Finalized()
+            # MPI can now be finalized, but MPI_Finalize is a collective and can act
+            # like a barrier (this may be implementation specific), if we are terminating
+            # due to a Julia exception, we should calling MPI_Finalize. We thus peek at the
+            # current exception, and only if that field is nothing do we terminate.
+            if ccall(:jl_current_exception, Any, ()) === nothing
+                _Finalize()
+            end
+        end
     end
 end
 

test/runtests.jl

@@ -22,7 +22,7 @@ function runtests()
 
     nfail = 0
     printstyled("Running MPI.jl tests\n"; color=:white)
-    
+
     for f in testfiles
         mpiexec() do cmd
             cmd = `$cmd $args`
@@ -32,6 +32,9 @@ function runtests()
                 withenv("JULIA_NUM_THREAD" => "4") do
                     run(`$cmd -n $nprocs $(Base.julia_cmd()) $(joinpath(testdir, f))`)
                 end
+            elseif f == "test_error.jl"
+                r = run(ignorestatus(`$cmd -n $nprocs $(Base.julia_cmd()) $(joinpath(testdir, f))`))
+                @test !success(r)
             else
                 run(`$cmd -n $nprocs $(Base.julia_cmd()) $(joinpath(testdir, f))`)
             end

test/test_error.jl

@@ -0,0 +1,11 @@
+using MPI
+function main()
+    MPI.Init()
+    comm = MPI.COMM_WORLD
+    rank = MPI.Comm_rank(comm)
+    if rank == 1
+        error("Goodbye")
+    end
+    MPI.Barrier(comm)
+end
+main()