fix get histogram memory leak and some failed cases

deps/oblib/src/lib/stat/ob_di_tls.h

@@ -18,10 +18,10 @@
 
 namespace oceanbase
 {
-namespace common
-{
-
-template <class T>
+namespace common
+{
+
+template <class T>
 class ObDITls
 {
 public:
@@ -66,5 +66,5 @@ T* ObDITls<T>::get_instance()
 }
 
 }
-}
-#endif
+}
+#endif

src/share/stat/ob_opt_column_stat.h

@@ -89,7 +89,7 @@ public:
     pop_count_(0)
     {}
 
-  ~ObHistogram() {}
+  ~ObHistogram() { reset(); }
 
   void reset();
 
@@ -219,7 +219,7 @@ public:
 
   explicit ObOptColumnStat(common::ObIAllocator &allocator);
 
-  ~ObOptColumnStat() {}
+  ~ObOptColumnStat() { histogram_.reset(); }
 
   uint64_t get_table_id() const { return table_id_; }
   void set_table_id(uint64_t tid) { table_id_ = tid; }

src/share/stat/ob_opt_stat_service.cpp

@@ -237,7 +237,10 @@ int ObOptStatService::load_column_stat_and_put_cache(const uint64_t tenant_id,
         LOG_WARN("puts column stat into cache failed.", K(ret));
       } else if (OB_FAIL(handles.push_back(handle))) {
         LOG_WARN("failed to push back", K(ret));
-      } else {/*do nothing*/}
+      } else {
+        key_column_stats.at(i).stat_->~ObOptColumnStat();
+        key_column_stats.at(i).stat_ = NULL;
+      }
     }
   }
   return ret;