fix alloc local session with same sid leads memory damage

src/sql/engine/ob_des_exec_context.cpp

@@ -109,10 +109,13 @@ int ObDesExecContext::create_my_session(uint64_t tenant_id)
         LOG_ERROR("no more memory to create sql session info");
       } else {
         local_session = new (local_session) ObSQLSessionInfo();
-        uint32_t tmp_sid = 123456789;
+        uint32_t tmp_sid = 0;
+        uint64_t tmp_proxy_sessid = proxy_sid;
         uint32_t tmp_version = 0;
-        uint64_t tmp_proxy_sessid = 1234567890;
-        if (OB_FAIL(local_session->init(tmp_version, tmp_sid, tmp_proxy_sessid, NULL))) {
+        bool session_in_mgr = false;
+        if (OB_FAIL(GCTX.session_mgr_->create_sessid(tmp_sid, session_in_mgr))) {
+          LOG_WARN("failed to mock session id", K(ret));
+        } else if (OB_FAIL(local_session->init(tmp_version, tmp_sid, tmp_proxy_sessid, NULL))) {
           LOG_WARN("my session init failed", K(ret));
           local_session->~ObSQLSessionInfo();
         } else {

src/sql/session/ob_sql_session_mgr.cpp

@@ -282,11 +282,11 @@ int ObSQLSessionMgr::inc_session_ref(const ObSQLSessionInfo* my_session)
 // |Mask|          Server Id           |           Local Seq            |
 // +----+------------------------------+--------------------------------+
 //
-// MASK: 1 means session_id is generated by observer, 0 means by proxy.
+// MASK: 1 means session_id is generated by observer, 0 means in_mgr = false.
 // Server Id: generated by root server, and unique in cluster.
 // Local Seq: max session number in an observer.
 //
-int ObSQLSessionMgr::create_sessid(uint32_t& sessid)
+int ObSQLSessionMgr::create_sessid(uint32_t &sessid, bool in_mgr)
 {
   int ret = OB_SUCCESS;
   int tmp_ret = OB_SUCCESS;
@@ -297,6 +297,9 @@ int ObSQLSessionMgr::create_sessid(uint32_t& sessid)
   if (server_id > MAX_SERVER_ID) {
     ret = OB_ERR_UNEXPECTED;
     LOG_ERROR("server id maybe invalid", K(ret), K(server_id));
+  } else if (!in_mgr) {
+    sessid = (GETTID() | LOCAL_SESSID_TAG);
+    sessid |= static_cast<uint32_t>(server_id << LOCAL_SEQ_LEN);  // set observer
   } else if (0 == server_id) {
     local_seq = (ATOMIC_FAA(&abnormal_seq, 1) & MAX_LOCAL_SEQ);
     uint32_t max_local_seq = MAX_LOCAL_SEQ;
@@ -307,7 +310,7 @@ int ObSQLSessionMgr::create_sessid(uint32_t& sessid)
   } else { /*do nothing*/
   }
 
-  if (OB_SUCC(ret)) {
+  if (OB_SUCC(ret) && in_mgr) {
     sessid = local_seq | SERVER_SESSID_TAG;                       // set observer sessid mark
     sessid |= static_cast<uint32_t>(server_id << LOCAL_SEQ_LEN);  // set observer
     // high bit is reserved for server id

src/sql/session/ob_sql_session_mgr.h

@@ -47,6 +47,7 @@ public:
   static const uint32_t NON_DURABLE_VALUE = 0;
   static const uint32_t MAX_VERSION = UINT8_MAX;  // 255
   static const uint32_t SERVER_SESSID_TAG = 1ULL << 31;
+  static const uint32_t LOCAL_SESSID_TAG = 0;  // used for sessions overflow
   typedef SessionInfoKey Key;
   explicit ObSQLSessionMgr(storage::ObPartitionService* partition_service)
       :  // null_callback_(),
@@ -121,11 +122,11 @@ public:
   }
   static int is_need_clear_sessid(const observer::ObSMConnection* conn, bool& is_need);
   int fetch_first_sessid();
-  int create_sessid(uint32_t& sessid);
+  //  in_mgr = false means fail back to local session allocating, avoid remote/distribute executing fail
+  int create_sessid(uint32_t& sessid, bool in_mgr = true);
   int mark_sessid_used(uint32_t sess_id);
   int mark_sessid_unused(uint32_t sess_id);
   // inline ObNullEndTransCallback &get_null_callback() { return null_callback_; }
-private:
   int create_session_by_version(
       uint64_t tenant_id, uint32_t sessid, uint64_t proxy_sessid, ObSQLSessionInfo*& sess_info, uint32_t& out_version);
   int get_avaiable_local_seq(uint32_t& local_seq);