diff --git a/sphinx/builders/__init__.py b/sphinx/builders/__init__.py
index 495cf9f694d..1ce2390653a 100644
--- a/sphinx/builders/__init__.py
+++ b/sphinx/builders/__init__.py
@@ -653,48 +653,50 @@ def on_chunk_done(args: list[tuple[str, NoneType]], result: NoneType) -> None:
             next(progress)
 
         self.app.phase = BuildPhase.RESOLVING
-        measure_1 = f'{__file__}: {inspect.currentframe().f_code.co_name}: get_doctree_write'
-        measure_2 = f'{__file__}: {inspect.currentframe().f_code.co_name}: write_doc_serialized'
-        for docname in docnames:
-            with TimeIt(measure_1, self.runtime, logger, False):
-                doctree = self.env.get_doctree_write(docname)
-            with TimeIt(measure_2, self.runtime, logger, False):
-                self.write_doc_serialized(docname, doctree)
-        logger.info(f'{measure_1}: {self.runtime[measure_1]}')
-        logger.info(f'{measure_2}: {self.runtime[measure_2]}')
-
-        with WorkerPool(n_jobs=nproc, start_method='fork', use_dill=False, pass_worker_id=True, enable_insights=True) as pool:
-            # args = []
-            # for docname in docnames:
-            #     doctree = self.env.get_and_resolve_doctree(docname, self)
-            #     self.write_doc_serialized(docname, doctree)
-            #     args.append([(docname, doctree)])
-            # import pickle
-
-            # from dill import dumps, loads
-            # doctree_dilled = dumps(args[0][0][1], protocol=pickle.HIGHEST_PROTOCOL)
-            # doctree_readback = loads(doctree_dilled)
-            with TimeIt(f'{__file__}: {inspect.currentframe().f_code.co_name}: WorkerPool', self.runtime, logger):
-                results = pool.map(write_process, docnames, worker_lifespan=5, progress_bar=True)
-            for result in results:
-                warnings, images = result
-                for warning in warnings:
-                    logger.warning(warning)
-                self.images.update(images)
-            insights = pool.get_insights()
-            import json
-            print(json.dumps(insights, indent=2))
-            # print(insights)
-        # for chunk in chunks:
-        #     arg = []
-        #     for docname in chunk:
-        #         doctree = self.env.get_and_resolve_doctree(docname, self)
-        #         self.write_doc_serialized(docname, doctree)
-        #         arg.append((docname, doctree))
-        #     tasks.add_task(write_process, arg, on_chunk_done)
-
-        # # make sure all threads have finished
-        # tasks.join()
+        if docnames:
+            measure_1 = f'{__file__}: {inspect.currentframe().f_code.co_name}: get_doctree_write'
+            measure_2 = f'{__file__}: {inspect.currentframe().f_code.co_name}: write_doc_serialized'
+            for docname in docnames:
+                with TimeIt(measure_1, self.runtime, logger, False):
+                    doctree = self.env.get_doctree_write(docname)
+                with TimeIt(measure_2, self.runtime, logger, False):
+                    self.write_doc_serialized(docname, doctree)
+            logger.info(f'{measure_1}: {self.runtime[measure_1]}')
+            logger.info(f'{measure_2}: {self.runtime[measure_2]}')
+
+            with WorkerPool(n_jobs=nproc, start_method='fork', use_dill=False, pass_worker_id=True, enable_insights=True) as pool:
+                # args = []
+                # for docname in docnames:
+                #     doctree = self.env.get_and_resolve_doctree(docname, self)
+                #     self.write_doc_serialized(docname, doctree)
+                #     args.append([(docname, doctree)])
+                # import pickle
+
+                # from dill import dumps, loads
+                # doctree_dilled = dumps(args[0][0][1], protocol=pickle.HIGHEST_PROTOCOL)
+                # doctree_readback = loads(doctree_dilled)
+                with TimeIt(f'{__file__}: {inspect.currentframe().f_code.co_name}: WorkerPool', self.runtime, logger):
+                    results = pool.map(write_process, docnames, worker_lifespan=5, progress_bar=True)
+                for result in results:
+                    warnings, images = result
+                    for warning in warnings:
+                        logger.warning(warning)
+                    self.images.update(images)
+                insights = pool.get_insights()
+                import json
+                print(json.dumps(insights, indent=2))
+                # print(insights)
+            # for chunk in chunks:
+            #     arg = []
+            #     for docname in chunk:
+            #         doctree = self.env.get_and_resolve_doctree(docname, self)
+            #         self.write_doc_serialized(docname, doctree)
+            #         arg.append((docname, doctree))
+            #     tasks.add_task(write_process, arg, on_chunk_done)
+
+            # # make sure all threads have finished
+            # tasks.join()
+        import json
         print(json.dumps(self.runtime, indent=2))
         logger.info('')