[14_0_X] Avoid releasing WaitingTask too early in case of exception in WaitingThreadPool

FWCore/Concurrency/interface/WaitingTaskHolder.h

@@ -83,7 +83,7 @@ namespace edm {
     /** Use in the case where you need to inform the parent task of a
      failure before some other child task which may be run later reports
      a different, but related failure. You must later call doneWaiting
-     in the same thread passing the same exceptoin.
+     in the same thread passing the same exception.
      */
     void presetTaskAsFailed(std::exception_ptr iExcept) {
       if (iExcept) {

FWCore/Concurrency/interface/WaitingTaskWithArenaHolder.h

@@ -60,6 +60,12 @@ namespace edm {
     // the task. doneWaiting can be called from a non-TBB thread.
     void doneWaiting(std::exception_ptr iExcept);
 
+    // Use in the case where you need to inform the parent task of a
+    // failure before some other child task which may be run later
+    // reports a different, but related failure. You must later call
+    // doneWaiting in the same thread passing the same exception.
+    void presetTaskAsFailed(std::exception_ptr iExcept) noexcept;
+
     // This next function is useful if you know from the context that
     // m_arena (which is set when the constructor was executes) is the
     // same arena in which you want to execute the doneWaiting function.

FWCore/Concurrency/interface/WaitingThreadPool.h

@@ -34,7 +34,10 @@ namespace edm {
             convertException::wrap([&func]() { func(); });
           } catch (cms::Exception& e) {
             e.addContext(errorContext());
-            holder.doneWaiting(std::current_exception());
+            // doneWaiting() is intentionally not called here. The
+            // reference count decrement must be done only in
+            // threadLoop() (see the comment there)
+            holder.presetTaskAsFailed(std::current_exception());
           }
         };
         thisPtr_ = std::move(thisPtr);

FWCore/Concurrency/src/WaitingTaskWithArenaHolder.cc

@@ -90,6 +90,12 @@ namespace edm {
     }
   }
 
+  void WaitingTaskWithArenaHolder::presetTaskAsFailed(std::exception_ptr iExcept) noexcept {
+    if (iExcept) {
+      m_task->dependentTaskFailed(iExcept);
+    }
+  }
+
   // This next function is useful if you know from the context that
   // m_arena (which is set when the  constructor was executes) is the
   // same arena in which you want to execute the doneWaiting function.