[bugfix][AsyncOutput] Restore asynchronicity for output and make sure

that all output is written before the simulator is finalized.

ebos/eclproblem.hh

@@ -1056,6 +1056,12 @@ public:
             eclWriter_->writeOutput(isSubStep);
     }
 
+    void finalizeOutput() {
+        // this will write all pending output to disk
+        // to avoid corruption of output files
+        eclWriter_.reset();
+    }
+
 
     void applyActions(int reportStep,
                       double sim_time,

opm/simulators/flow/SimulatorFullyImplicitBlackoilEbos.hpp

@@ -277,6 +277,15 @@ public:
 
         }
 
+        // make sure all output is written to disk before run is finished
+        {
+            Dune::Timer finalOutputTimer;
+            finalOutputTimer.start();
+
+            ebosSimulator_.problem().finalizeOutput();
+            report.output_write_time += finalOutputTimer.stop();
+        }
+
         // Stop timer and create timing report
         totalTimer.stop();
         report.total_time = totalTimer.secsSinceStart();