Release dependent modules only after the worker has finished for scheduled modules

FWCore/Framework/interface/maker/Worker.h

@@ -241,6 +241,9 @@ namespace edm {
 
     virtual bool hasAccumulator() const = 0;
 
+    // Used in PuttableProductResolver
+    edm::WaitingTaskList& waitingTaskList() { return waitingTasks_; }
+
   protected:
     template <typename O>
     friend class workerhelper::CallImpl;

FWCore/Framework/src/ProductResolvers.cc

@@ -407,47 +407,21 @@ namespace edm {
         }
       }
 
-      //Need to try modifying prefetchRequested_ before adding to m_waitingTasks
-      bool expected = false;
-      bool prefetchRequested = prefetchRequested_.compare_exchange_strong(expected, true);
-      m_waitingTasks.add(waitTask);
-
-      if (worker_ and prefetchRequested) {
-        //using a waiting task to do a callback guarantees that
-        // the m_waitingTasks list will be released from waiting even
-        // if the module does not put this data product or the
-        // module has an exception while running
-
-        auto waiting = make_waiting_task([this](std::exception_ptr const* iException) {
-          if (nullptr != iException) {
-            m_waitingTasks.doneWaiting(*iException);
-          } else {
-            m_waitingTasks.doneWaiting(std::exception_ptr());
-          }
-        });
-        worker_->callWhenDoneAsync(WaitingTaskHolder(*waitTask.group(), waiting));
+      if (waitingTasks_) {
+        // using a waiting task to do a callback guarantees that the
+        // waitingTasks_ list (from the worker) will be released from
+        // waiting even if the module does not put this data product
+        // or the module has an exception while running
+        waitingTasks_->add(waitTask);
       }
     }
   }
 
-  void PuttableProductResolver::putProduct(std::unique_ptr<WrapperBase> edp) const {
-    ProducedProductResolver::putProduct(std::move(edp));
-    bool expected = false;
-    if (prefetchRequested_.compare_exchange_strong(expected, true)) {
-      m_waitingTasks.doneWaiting(std::exception_ptr());
-    }
-  }
-
-  void PuttableProductResolver::resetProductData_(bool deleteEarly) {
-    if (not deleteEarly) {
-      prefetchRequested_ = false;
-      m_waitingTasks.reset();
-    }
-    DataManagingProductResolver::resetProductData_(deleteEarly);
-  }
-
   void PuttableProductResolver::setupUnscheduled(UnscheduledConfigurator const& iConfigure) {
-    worker_ = iConfigure.findWorker(branchDescription().moduleLabel());
+    auto worker = iConfigure.findWorker(branchDescription().moduleLabel());
+    if (worker) {
+      waitingTasks_ = &worker->waitingTaskList();
+    }
   }
 
   void UnscheduledProductResolver::setupUnscheduled(UnscheduledConfigurator const& iConfigure) {

FWCore/Framework/src/ProductResolvers.h

@@ -201,7 +201,7 @@ namespace edm {
   class PuttableProductResolver : public ProducedProductResolver {
   public:
     explicit PuttableProductResolver(std::shared_ptr<BranchDescription const> bd)
-        : ProducedProductResolver(bd, ProductStatus::NotPut), worker_(nullptr), prefetchRequested_(false) {}
+        : ProducedProductResolver(bd, ProductStatus::NotPut) {}
 
     void setupUnscheduled(UnscheduledConfigurator const&) final;
 
@@ -218,12 +218,12 @@ namespace edm {
                         ModuleCallingContext const* mcc) const override;
     bool unscheduledWasNotRun_() const override { return false; }
 
-    void putProduct(std::unique_ptr<WrapperBase> edp) const override;
-    void resetProductData_(bool deleteEarly) override;
-
-    CMS_THREAD_SAFE mutable WaitingTaskList m_waitingTasks;
-    Worker* worker_;
-    mutable std::atomic<bool> prefetchRequested_;
+    // The WaitingTaskList below is the one from the worker, if one
+    // corresponds to this ProductResolver. For the Source-like cases
+    // where there is no such Worker, the tasks depending on the data
+    // depending on this ProductResolver are assumed to be eligible to
+    // run immediately after their prefetch.
+    WaitingTaskList* waitingTasks_ = nullptr;
   };
 
   class UnscheduledProductResolver : public ProducedProductResolver {

FWCore/Framework/src/StreamSchedule.cc

@@ -890,6 +890,12 @@ namespace edm {
       ServiceRegistry::Operate guard(serviceToken);
       Traits::preScheduleSignal(actReg_.get(), &streamContext_);
 
+      // Data dependencies need to be set up before marking empty
+      // (End)Paths complete in case something consumes the status of
+      // the empty (EndPath)
+      workerManager_.setupResolvers(ep);
+      workerManager_.setupOnDemandSystem(info);
+
       HLTPathStatus hltPathStatus(hlt::Pass, 0);
       for (int empty_trig_path : empty_trig_paths_) {
         results_->at(empty_trig_path) = hltPathStatus;
@@ -912,9 +918,6 @@ namespace edm {
         }
       }
 
-      workerManager_.setupResolvers(ep);
-      workerManager_.setupOnDemandSystem(info);
-
       ++total_events_;
 
       //use to give priorities on an error to ones from Paths