Rebuild graph when it's out of time. (#4607)

### What problem does this PR solve?

#4543

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [x] Refactoring

rag/nlp/search.py

@@ -483,4 +483,4 @@ class Dealer:
         cnt = np.sum([c for _, c in aggs])
         tag_fea = sorted([(a, round(0.1*(c + 1) / (cnt + S) / (all_tags.get(a, 0.0001)))) for a, c in aggs],
                          key=lambda x: x[1] * -1)[:topn_tags]
-        return {a: c for a, c in tag_fea if c > 0}
+        return {a: max(1, c) for a, c in tag_fea}

rag/svr/task_executor.py

@@ -327,8 +327,10 @@ def build_chunks(task, progress_callback):
                                          random.choices(examples, k=2) if len(examples)>2 else examples,
                                          topn=topn_tags)
                 if cached:
-                    set_llm_cache(chat_mdl.llm_name, d["content_with_weight"], cached, all_tags, {"topn": topn_tags})
-            d[TAG_FLD] = json.loads(cached)
+                    cached = json.dumps(cached)
+            if cached:
+                set_llm_cache(chat_mdl.llm_name, d["content_with_weight"], cached, all_tags, {"topn": topn_tags})
+                d[TAG_FLD] = json.loads(cached)
 
         progress_callback(msg="Tagging completed in {:.2f}s".format(timer() - st))