Lazy init PipelineManager

Author: r4victor

src/dstack/_internal/server/background/pipeline_tasks/__init__.py

@@ -85,10 +85,13 @@ def hint_fetch(self, model_name: str):
             pipeline.hint_fetch()
 
 
-_pipeline_manager = PipelineManager()
+_pipeline_manager = None
 
 
 def get_pipeline_manager() -> PipelineManager:
+    global _pipeline_manager
+    if _pipeline_manager is None:
+        _pipeline_manager = PipelineManager()
     return _pipeline_manager
 
 
@@ -97,5 +100,6 @@ def start_pipeline_tasks() -> PipelineManager:
     Start tasks processed by fetch-workers pipelines based on db + in-memory queues.
     Suitable for tasks that run frequently and need to lock rows for a long time.
     """
-    _pipeline_manager.start()
-    return _pipeline_manager
+    pipeline_manager = get_pipeline_manager()
+    pipeline_manager.start()
+    return pipeline_manager