fix:error in limit for tmq group

source/dnode/mnode/impl/inc/mndSubscribe.h

@@ -25,6 +25,7 @@ extern "C" {
 int32_t mndInitSubscribe(SMnode *pMnode);
 void    mndCleanupSubscribe(SMnode *pMnode);
 
+int32_t          mndGetGroupNumByTopic(SMnode *pMnode, const char *topicName);
 SMqSubscribeObj *mndAcquireSubscribe(SMnode *pMnode, const char *CGroup, const char *topicName);
 SMqSubscribeObj *mndAcquireSubscribeByKey(SMnode *pMnode, const char *key);
 void             mndReleaseSubscribe(SMnode *pMnode, SMqSubscribeObj *pSub);

source/dnode/mnode/impl/src/mndConsumer.c

@@ -645,18 +645,12 @@ int32_t mndProcessSubscribeReq(SRpcMsg *pMsg) {
 
   int32_t newTopicNum = taosArrayGetSize(pTopicList);
   for(int i = 0; i < newTopicNum; i++){
-    SMqSubscribeObj *pSub = mndAcquireSubscribe(pMnode, (const char*)cgroup, (const char*)taosArrayGetP(pTopicList, i));
-    if(pSub == NULL) continue;
-    taosRLockLatch(&pSub->lock);
-    if(taosHashGetSize(pSub->consumerHash) > MND_MAX_GROUP_PER_TOPIC){
+    int32_t gNum = mndGetGroupNumByTopic(pMnode, (const char*)taosArrayGetP(pTopicList, i));
+    if(gNum > MND_MAX_GROUP_PER_TOPIC){
       terrno = TSDB_CODE_TMQ_GROUP_OUT_OF_RANGE;
       code = terrno;
-      taosRUnLockLatch(&pSub->lock);
-      mndReleaseSubscribe(pMnode, pSub);
       goto _over;
     }
-    taosRUnLockLatch(&pSub->lock);
-    mndReleaseSubscribe(pMnode, pSub);
   }
 
   // check topic existence

source/dnode/mnode/impl/src/mndSubscribe.c

@@ -952,6 +952,32 @@ SMqSubscribeObj *mndAcquireSubscribeByKey(SMnode *pMnode, const char *key) {
   return pSub;
 }
 
+int32_t mndGetGroupNumByTopic(SMnode *pMnode, const char *topicName) {
+  int32_t num = 0;
+  SSdb   *pSdb = pMnode->pSdb;
+
+  void            *pIter = NULL;
+  SMqSubscribeObj *pSub = NULL;
+  while (1) {
+    pIter = sdbFetch(pSdb, SDB_SUBSCRIBE, pIter, (void **)&pSub);
+    if (pIter == NULL) break;
+
+
+    char topic[TSDB_TOPIC_FNAME_LEN];
+    char cgroup[TSDB_CGROUP_LEN];
+    mndSplitSubscribeKey(pSub->key, topic, cgroup, true);
+    if (strcmp(topic, topicName) != 0) {
+      sdbRelease(pSdb, pSub);
+      continue;
+    }
+
+    num++;
+    sdbRelease(pSdb, pSub);
+  }
+
+  return num;
+}
+
 void mndReleaseSubscribe(SMnode *pMnode, SMqSubscribeObj *pSub) {
   SSdb *pSdb = pMnode->pSdb;
   sdbRelease(pSdb, pSub);