Merge pull request #4766 from taosdata/hotfix/TD-2604

[TD-2604]<hotfix>: fix coredump

src/tsdb/src/tsdbMemTable.c

@@ -207,10 +207,10 @@ void *tsdbAllocBytes(STsdbRepo *pRepo, int bytes) {
 int tsdbAsyncCommit(STsdbRepo *pRepo) {
   if (pRepo->mem == NULL) return 0;
 
-  ASSERT(pRepo->imem == NULL);
-
   sem_wait(&(pRepo->readyToCommit));
 
+  ASSERT(pRepo->imem == NULL);
+
   if (pRepo->code != TSDB_CODE_SUCCESS) {
     tsdbWarn("vgId:%d try to commit when TSDB not in good state: %s", REPO_ID(pRepo), tstrerror(terrno));
   }