refactor: simplify logging statements and fix deadlock in batch error handling

- Consolidate multi-line logging statements into single lines for consistency
- Add critical note about lock acquisition in _save_batch docstring
- Fix potential deadlock: remove lock acquisition in error handler as caller already holds lock
- Remove trailing whitespace in process_with_strategy

pipeline/base_pipeline.py

@@ -234,13 +234,9 @@ class BasePipeline(ABC):
                     if file_path.exists():
                         data = self._load_single_data_file(file_path, data_parser)
                         all_data.extend(data)
-                        self.logger.info(
-                            f"Loaded {len(data)} {data_type} from {file_path}"
-                        )
+                        self.logger.info(f"Loaded {len(data)} {data_type} from {file_path}")
                     else:
-                        self.logger.warning(
-                            f"{data_type} file does not exist: {file_path}"
-                        )
+                        self.logger.warning(f"{data_type} file does not exist: {file_path}")
                 except Exception as e:
                     self.logger.error(
                         f"Failed to load {data_type} file {file_path}: {e}",
@@ -297,13 +293,9 @@ class BasePipeline(ABC):
                         if file_path.exists():
                             data = self._load_single_data_file(file_path, data_parser)
                             all_data.extend(data)
-                            self.logger.info(
-                                f"Loaded {len(data)} {data_type} from {file_path}"
-                            )
+                            self.logger.info(f"Loaded {len(data)} {data_type} from {file_path}")
                         else:
-                            self.logger.warning(
-                                f"{data_type} file does not exist: {file_path}"
-                            )
+                            self.logger.warning(f"{data_type} file does not exist: {file_path}")
                     except Exception as e:
                         self.logger.error(
                             f"Failed to load {data_type} file {file_path}: {e}",
@@ -581,9 +573,7 @@ class BatchSaveManager:
         """
         self.pipeline = pipeline
         self.output_filename = output_filename
-        self.batch_size = (
-            batch_size if batch_size is not None else pipeline.config.batch_size
-        )
+        self.batch_size = batch_size if batch_size is not None else pipeline.config.batch_size
         self.flush_on_exit = flush_on_exit
 
         # Result buffer
@@ -632,7 +622,11 @@ class BatchSaveManager:
         self._save_batch(batch)
 
     def _save_batch(self, batch: List[Dict]) -> None:
-        """Save a batch of results"""
+        """Save a batch of results
+
+        Note: This method may be called while holding self.lock.
+        Any exception handling must NOT attempt to acquire the lock again.
+        """
         try:
             # Use incremental save method
             self.pipeline.save_results_incrementally(batch, self.output_filename)
@@ -650,8 +644,9 @@ class BatchSaveManager:
         except Exception as e:
             self.pipeline.logger.error(f"Batch save failed: {e}")
             # Put failed results back into buffer
-            with self.lock:
-                self.buffer.extend(batch)
+            # IMPORTANT: Do NOT acquire lock here - caller already holds it
+            # (see _flush_unlocked and add_results methods)
+            self.buffer.extend(batch)
             raise
 
     def flush(self) -> None:
@@ -780,7 +775,6 @@ def process_with_strategy(
         total_items=len(items),
         desc=desc,
     ) as save_manager:
-
         # Define wrapper function to add results to save manager
         def wrapped_process_func(item):
             try: