feat: Ensure thread safety for graph write operations

Add a lock to delete, adelete_by_entity, and adelete_by_relation methods to prevent race conditions and ensure data consistency during concurrent modifications to the knowledge graph.

lightrag/lightrag.py

@@ -35,6 +35,7 @@ from lightrag.kg import (
 from lightrag.kg.shared_storage import (
     get_namespace_data,
     get_pipeline_status_lock,
+    get_graph_db_lock,
 )
 
 from .base import (
@@ -1728,6 +1729,10 @@ class LightRAG:
             relationships_to_delete = set()
             relationships_to_rebuild = {}  # (src, tgt) -> remaining_chunk_ids
 
+            # Use graph database lock to ensure atomic merges and updates
+            graph_db_lock = get_graph_db_lock(enable_logging=False)
+            async with graph_db_lock:
+
                 # Process entities
                 all_labels = await self.chunk_entity_relation_graph.get_all_labels()
                 for node_label in all_labels:
@@ -1857,6 +1862,9 @@ class LightRAG:
         """
         from .utils_graph import adelete_by_entity
 
+        # Use graph database lock to ensure atomic merges and updates
+        graph_db_lock = get_graph_db_lock(enable_logging=False)
+        async with graph_db_lock:
             return await adelete_by_entity(
                 self.chunk_entity_relation_graph,
                 self.entities_vdb,
@@ -1877,6 +1885,9 @@ class LightRAG:
         """
         from .utils_graph import adelete_by_relation
 
+        # Use graph database lock to ensure atomic merges and updates
+        graph_db_lock = get_graph_db_lock(enable_logging=False)
+        async with graph_db_lock:
             return await adelete_by_relation(
                 self.chunk_entity_relation_graph,
                 self.relationships_vdb,