fix the bug of non-exit, test=develop (#27350)

paddle/fluid/framework/device_worker.h

@@ -441,6 +441,7 @@ class SectionWorker : public DeviceWorker {
     skip_vars_ = skip_vars;
   }
   static void ResetBatchId() { batch_id_ = 0; }
+  static void ResetThreadCompletedFlag() { threads_completed = false; }
 
   static std::atomic<int> cpu_id_;
 

paddle/fluid/framework/pipeline_trainer.cc

@@ -251,6 +251,7 @@ void PipelineTrainer::Finalize() {
   }
   root_scope_->DropKids();
   SectionWorker::ResetBatchId();
+  SectionWorker::ResetThreadCompletedFlag();
 }
 
 Scope* PipelineTrainer::GetWorkerScope(int thread_id) {

paddle/fluid/framework/section_worker.cc

@@ -196,7 +196,6 @@ void SectionWorker::TrainFiles() {
         if (threads_completed) {
           VLOG(3) << "thread " << thread_id_ << " completed.";
           lk.unlock();
-          threads_completed = false;
           return;
         }
         lk.unlock();
@@ -459,7 +458,6 @@ void SectionWorker::TrainFilesWithProfiler() {
                     << ", mean_time: " << op_total_time[i] / op_count[i];
           }
           VLOG(0) << "================================";
-          threads_completed = false;
           return;
         }
         lk.unlock();