Merge pull request #3734 from taosdata/patch/TD-1628

TD-1628

src/rpc/src/rpcCache.c

@@ -216,6 +216,7 @@ static void rpcCleanConnCache(void *handle, void *tmrId) {
   if (pCache == NULL || pCache->maxSessions == 0) return;
   if (pCache->pTimer != tmrId) return;
 
+  pthread_mutex_lock(&pCache->mutex);
   uint64_t time = taosGetTimestampMs();
 
   for (hash = 0; hash < pCache->maxSessions; ++hash) {
@@ -227,6 +228,7 @@ static void rpcCleanConnCache(void *handle, void *tmrId) {
 
   // tTrace("timer, total connections in cache:%d", pCache->total);
   taosTmrReset(rpcCleanConnCache, (int32_t)(pCache->keepTimer * 2), pCache, pCache->tmrCtrl, &pCache->pTimer);
+  pthread_mutex_unlock(&pCache->mutex);
 }
 
 static void rpcRemoveExpiredNodes(SConnCache *pCache, SConnHash *pNode, int hash, uint64_t time) {