properly drop barrier when using iterrative aggregation

qdp_project/src/Benchmark.cpp

@@ -294,12 +294,15 @@ void aggr_j(size_t gid, size_t tid) {
 
     THREAD_TIMING_[AGGRJ_TIMING_INDEX][tid * gid][0][TIME_STAMP_END] = std::chrono::steady_clock::now();
 
-    BARRIERS_[gid]->arrive_and_drop();
+    if constexpr (!AGGRJ_ITERATIVE) {
+        BARRIERS_[gid]->arrive_and_drop();
+    }
 
     aggregation::happly(DATA_DST_ + (tid * GROUP_COUNT + gid), aggregator);
 
     if constexpr (AGGRJ_ITERATIVE) {
         if (++tid < TC_AGGRJ) aggr_j(gid, tid);
+        else BARRIERS_[gid]->arrive_and_drop();
     }
 }