TaskSystem: Fix early shutdown

... conceptually, it was possible that a previous task
decrements the `num_threads_running_` counter before it is
incremented by the next task. Therefore, we have to unify
the queue and thread status in a single counter
(`total_workload_`) and ensure that woken threads increment
it before decrementing it for popping a queue.

1 files changed, 5 insertions, 8 deletions

diff --git a/test/buildtool/multithreading/task_system.test.cpp b/test/buildtool/multithreading/task_system.test.cpp
index 21e1ca6e..d34e3e4b 100644
--- a/test/buildtool/multithreading/task_system.test.cpp
+++ b/test/buildtool/multithreading/task_system.test.cpp
@@ -174,14 +174,11 @@ TEST_CASE("All threads run until work is done", "[task_system]") {
             // Wait some time for all threads to go to sleep.
             std::this_thread::sleep_for(1s);
 
-            // Run singe task that creates the actual store tasks. All threads
-            // should stay alive until their corresponding queue is filled.
-            ts.QueueTask([&ts, &store_id] {
-                // One task per thread (assumes round-robin push to queues).
-                for (std::size_t i{}; i < ts.NumberOfThreads(); ++i) {
-                    ts.QueueTask([&store_id] { store_id(); });
-                }
-            });
+            // All threads should stay alive until their corresponding queue is
+            // filled. One task per thread (assumes round-robin push to queues).
+            for (std::size_t i{}; i < ts.NumberOfThreads(); ++i) {
+                ts.QueueTask([&store_id] { store_id(); });
+            }
         }
         CHECK(tids.size() == kNumThreads);
     }