deferred

Author: Devjiu

omniscidb/ResultSetRegistry/ColumnarResults.cpp

@@ -27,6 +27,7 @@
 #include <atomic>
 #include <future>
 #include <numeric>
+#include <ranges>
 
 EXTERN extern bool g_is_test_env;
 
@@ -672,7 +673,7 @@ void ColumnarResults::materializeAllLazyColumns(
                << " work_count: " << worker_count << " num_cols: " << num_columns;
     for (auto interval : makeIntervals(first, last, worker_count)) {
       conversion_threads.push_back(std::async(
-          std::launch::async,
+          std::launch::deferred,
           [&do_work_just_lazy_columns, &targets_to_skip, first, this](const size_t start,
                                                                       const size_t end) {
             for (size_t i = start; i < end; ++i) {
@@ -684,8 +685,10 @@ void ColumnarResults::materializeAllLazyColumns(
     }
 
     try {
-      for (auto& child : conversion_threads) {
-        child.wait();
+      for (auto it_child = conversion_threads.rbegin();
+           it_child != conversion_threads.rend();
+           ++it_child) {
+        it_child->wait();
       }
     } catch (...) {
       throw;