fix bug: plan cache core is caused by the plan cache diagnostic view.

src/observer/virtual_table/ob_all_plan_cache_stat.cpp

@@ -209,7 +209,7 @@ int ObAllPlanCacheStat::fill_cells(ObPlanCache &plan_cache)
       break;
     }
     case GV_SQL: {
-      SET_REF_HANDLE_COL(GV_SQL_HANDLE);
+      SET_REF_HANDLE_COL(PC_DIAG_HANDLE);
       break;
     }
     case PL_ANON: {

src/observer/virtual_table/ob_all_virtual_sql_plan.cpp

@@ -557,11 +557,11 @@ int ObAllVirtualSqlPlan::prepare_next_plan()
     // !!!引用plan cache资源之前必须加ObReqTimeGuard
     ObReqTimeGuard req_timeinfo_guard;
     ObPlanCache *plan_cache = NULL;
-    ObCacheObjGuard guard(SQL_PLAN_HANDLE);
+    ObCacheObjGuard guard(PC_DIAG_HANDLE);
     int tmp_ret = OB_SUCCESS;
     MTL_SWITCH(tenant_id_) {
       plan_cache = MTL(ObPlanCache*);
-      if (OB_SUCCESS != (tmp_ret = plan_cache->ref_plan(plan_id_, guard))) {
+      if (OB_SUCCESS != (tmp_ret = plan_cache->ref_alloc_plan(plan_id_, guard))) {
         // should not panic
       } else if (FALSE_IT(plan = static_cast<ObPhysicalPlan*>(guard.get_cache_obj()))) {
         // do nothing

src/observer/virtual_table/ob_gv_sql.cpp

@@ -83,7 +83,7 @@ int ObGVSql::get_row_from_specified_tenant(uint64_t tenant_id, bool &is_end)
     plan_cache_ = MTL(ObPlanCache*);
     NG_TRACE(trav_ps_map_start);
     ObGetAllCacheIdOp plan_id_op(&plan_id_array_);
-    if (OB_FAIL(plan_cache_->foreach_cache_obj(plan_id_op))) {
+    if (OB_FAIL(plan_cache_->foreach_alloc_cache_obj(plan_id_op))) {
       SERVER_LOG(WARN, "fail to traverse id2stat_map");
     } else {
       plan_id_array_idx_ = 0;
@@ -113,8 +113,8 @@ int ObGVSql::get_row_from_specified_tenant(uint64_t tenant_id, bool &is_end)
         is_end = false;
         uint64_t plan_id= plan_id_array_.at(plan_id_array_idx_);
         ++plan_id_array_idx_;
-        ObCacheObjGuard guard(GV_SQL_HANDLE);
-        int tmp_ret = plan_cache_->ref_cache_obj(plan_id, guard); //plan引用计数加1
+        ObCacheObjGuard guard(PC_DIAG_HANDLE);
+        int tmp_ret = plan_cache_->ref_alloc_obj(plan_id, guard); //plan引用计数加1
 
         //如果当前plan_id对应的plan已被淘汰, 则忽略继续获取下一个plan
         if (OB_HASH_NOT_EXIST == tmp_ret) {

src/sql/plan_cache/ob_lib_cache_object_manager.cpp

@@ -132,7 +132,7 @@ void ObLCObjectManager::common_free(ObILibCacheObject *cache_obj,
   if (OB_ISNULL(cache_obj)) {
     // do nothing
   } else {
-    if (!cache_obj->added_lc()) {
+    if (ref_handle != PC_DIAG_HANDLE && !cache_obj->added_lc()) {
         cache_obj->set_logical_del_time(ObTimeUtility::current_monotonic_time());
         LOG_WARN("set logical del time", K(cache_obj->get_logical_del_time()),
                                          K(cache_obj->added_lc()),

src/sql/plan_cache/ob_pc_ref_handle.cpp

@@ -65,7 +65,8 @@ const char* ObCacheRefHandleMgr::handle_name(const CacheRefHandleID handle_id)
     "plan_baseline_handle",
     "tableapi_node_handle",
     "sql_plan_handle",
-    "callstmt_handle"
+    "callstmt_handle",
+    "pc_diag_handle"
   };
   static_assert(sizeof(handle_names)/sizeof(const char*) == MAX_HANDLE, "invalid handle name array");
   if (handle_id < MAX_HANDLE) {

src/sql/plan_cache/ob_pc_ref_handle.h

@@ -130,6 +130,7 @@ enum CacheRefHandleID
   TABLEAPI_NODE_HANDLE,
   SQL_PLAN_HANDLE,
   CALLSTMT_HANDLE,
+  PC_DIAG_HANDLE,
   MAX_HANDLE
 };
 

src/sql/plan_cache/ob_plan_cache.cpp

@@ -1707,7 +1707,7 @@ int ObPlanCache::ref_cache_obj(const ObCacheObjID obj_id, ObCacheObjGuard& guard
   int ret = OB_SUCCESS;
   ObCacheObjAtomicOp op(guard.ref_handle_);
   ObGlobalReqTimeService::check_req_timeinfo();
-  if (OB_FAIL(co_mgr_.atomic_get_alloc_cache_obj(obj_id, op))) {
+  if (OB_FAIL(co_mgr_.atomic_get_cache_obj(obj_id, op))) {
     SQL_PC_LOG(WARN, "failed to get update plan statistic", K(obj_id), K(ret));
   } else if (NULL == op.get_value()) {
     ret = OB_HASH_NOT_EXIST;
@@ -1736,6 +1736,40 @@ int ObPlanCache::ref_plan(const ObCacheObjID plan_id, ObCacheObjGuard& guard)
   return ret;
 }
 
+int ObPlanCache::ref_alloc_obj(const ObCacheObjID obj_id, ObCacheObjGuard& guard)
+{
+  int ret = OB_SUCCESS;
+  ObCacheObjAtomicOp op(guard.ref_handle_);
+  ObGlobalReqTimeService::check_req_timeinfo();
+  if (OB_FAIL(co_mgr_.atomic_get_alloc_cache_obj(obj_id, op))) {
+    SQL_PC_LOG(WARN, "failed to get update plan statistic", K(obj_id), K(ret));
+  } else if (NULL == op.get_value()) {
+    ret = OB_HASH_NOT_EXIST;
+  } else {
+    guard.cache_obj_ = op.get_value();
+  }
+  return ret;
+}
+
+int ObPlanCache::ref_alloc_plan(const ObCacheObjID plan_id, ObCacheObjGuard& guard)
+{
+  int ret = OB_SUCCESS;
+  ObILibCacheObject *cache_obj = NULL;
+  ObGlobalReqTimeService::check_req_timeinfo();
+  if (OB_FAIL(ref_alloc_obj(plan_id, guard))) { // inc ref count by 1
+    LOG_WARN("failed to ref cache obj", K(ret));
+  } else if (FALSE_IT(cache_obj = guard.cache_obj_)) {
+    // do nothing
+  } else if (OB_ISNULL(cache_obj)) {
+    ret = OB_ERR_UNEXPECTED;
+    LOG_WARN("unexpected null cache object", K(ret));
+  } else if (ObLibCacheNameSpace::NS_CRSR != cache_obj->get_ns()) {
+    ret = OB_ERR_UNEXPECTED;
+    LOG_WARN("this cache object is not a plan.", K(ret), K(cache_obj->get_ns()));
+  }
+  return ret;
+}
+
 int ObPlanCache::add_cache_obj_stat(ObILibCacheCtx &ctx, ObILibCacheObject *cache_obj)
 {
   int ret = OB_SUCCESS;

src/sql/plan_cache/ob_plan_cache.h

@@ -26,6 +26,11 @@
 #include "sql/plan_cache/ob_lib_cache_object_manager.h"
 namespace oceanbase
 {
+namespace observer
+{
+  class ObGVSql;
+  class ObAllVirtualSqlPlan;
+}
 namespace rpc
 {
   class ObLoadBaselineArg;
@@ -221,6 +226,8 @@ class ObPlanCache
 {
 friend class ObCacheObjectFactory;
 friend class ObPlanCacheEliminationTask;
+friend class observer::ObAllVirtualSqlPlan;
+friend class observer::ObGVSql;
 
 public:
   static const int64_t MAX_PLAN_SIZE = 20*1024*1024; //20M
@@ -421,6 +428,10 @@ public:
   int flush_lib_cache_by_ns(const ObLibCacheNameSpace ns);
   int flush_pl_cache();
 
+protected:
+  int ref_alloc_obj(const ObCacheObjID obj_id, ObCacheObjGuard& guard);
+  int ref_alloc_plan(const ObCacheObjID obj_id, ObCacheObjGuard& guard);
+
 private:
   DISALLOW_COPY_AND_ASSIGN(ObPlanCache);
   int add_plan_cache(ObILibCacheCtx &ctx,