diff --git a/include/libs/scheduler/scheduler.h b/include/libs/scheduler/scheduler.h
index 1e2ccf8705..8ab3b898ca 100644
--- a/include/libs/scheduler/scheduler.h
+++ b/include/libs/scheduler/scheduler.h
@@ -23,8 +23,6 @@ extern "C" {
 #include "catalog.h"
 #include "planner.h"
 
-extern tsem_t schdRspSem;
-
 typedef struct SQueryProfileSummary {
   int64_t startTs;  // Object created and added into the message queue
   int64_t endTs;    // the timestamp when the task is completed
@@ -101,8 +99,6 @@ void schedulerFreeJob(int64_t* job, int32_t errCode);
 
 void schedulerDestroy(void);
 
-void schdExecCallback(SExecResult* pResult, void* param, int32_t code);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/source/libs/scheduler/src/schDbg.c b/source/libs/scheduler/src/schDbg.c
index d6c2b638b8..deaaaec7c1 100644
--- a/source/libs/scheduler/src/schDbg.c
+++ b/source/libs/scheduler/src/schDbg.c
@@ -16,17 +16,5 @@
 #include "query.h"
 #include "schInt.h"
 
-tsem_t    schdRspSem;
 SSchDebug gSCHDebug = {0};
 
-void schdExecCallback(SExecResult* pResult, void* param, int32_t code) {
-  if (code) {
-    pResult->code = code;
-  }
-
-  *(SExecResult*)param = *pResult;
-
-  taosMemoryFree(pResult);
-
-  tsem_post(&schdRspSem);
-}
diff --git a/source/libs/scheduler/src/schFlowCtrl.c b/source/libs/scheduler/src/schFlowCtrl.c
index 8c2b65e125..1f6e7fbd63 100644
--- a/source/libs/scheduler/src/schFlowCtrl.c
+++ b/source/libs/scheduler/src/schFlowCtrl.c
@@ -50,6 +50,10 @@ int32_t schChkJobNeedFlowCtrl(SSchJob *pJob, SSchLevel *pLevel) {
   int32_t taskNum = taosArrayGetSize(pJob->dataSrcTasks);
   for (int32_t i = 0; i < taskNum; ++i) {
     SSchTask *pTask = *(SSchTask **)taosArrayGet(pJob->dataSrcTasks, i);
+    if (NULL == pTask) {
+      SCH_JOB_DLOG("fail to get the %dth task", i);
+      SCH_ERR_RET(TSDB_CODE_SCH_INTERNAL_ERROR);
+    }
 
     sum += pTask->plan->execNodeStat.tableNum;
   }
@@ -214,6 +218,10 @@ int32_t schLaunchTasksInFlowCtrlListImpl(SSchJob *pJob, SSchFlowControl *ctrl) {
 
   for (int32_t i = 0; i < taskNum; ++i) {
     pTask = *(SSchTask **)taosArrayGet(ctrl->taskList, i);
+    if (NULL == pTask) {
+      SCH_JOB_ELOG("fail to get the %dth task", i);
+      SCH_ERR_JRET(TSDB_CODE_SCH_INTERNAL_ERROR);
+    }
     SEp *ep = SCH_GET_CUR_EP(&pTask->plan->execNode);
 
     if (pTask->plan->execNodeStat.tableNum > remainNum && ctrl->execTaskNum > 0) {
@@ -243,6 +251,11 @@ int32_t schLaunchTasksInFlowCtrlListImpl(SSchJob *pJob, SSchFlowControl *ctrl) {
 
     if (i < (taskNum - 1)) {
       SSchTask *pLastTask = *(SSchTask **)taosArrayGetLast(ctrl->taskList);
+      if (NULL == pLastTask) {
+        SCH_JOB_ELOG("fail to get the last task, num:%d", taosArrayGetSize(ctrl->taskList));
+        SCH_ERR_JRET(TSDB_CODE_SCH_INTERNAL_ERROR);
+      }
+      
       if (remainNum < pLastTask->plan->execNodeStat.tableNum) {
         SCH_TASK_DLOG("no more task to launch, fqdn:%s, port:%d, remainNum:%" PRId64 ", remainExecTaskNum:%d, smallestInList:%d",
                       ep->fqdn, ep->port, ctrl->tableNumSum, ctrl->execTaskNum, pLastTask->plan->execNodeStat.tableNum);
diff --git a/source/libs/scheduler/src/schJob.c b/source/libs/scheduler/src/schJob.c
index 278768981a..9ad1c1ff30 100644
--- a/source/libs/scheduler/src/schJob.c
+++ b/source/libs/scheduler/src/schJob.c
@@ -47,6 +47,7 @@ void schUpdateJobErrCode(SSchJob *pJob, int32_t errCode) {
   return;
 
 _return:
+
   SCH_JOB_DLOG("job errCode updated to %s", tstrerror(errCode));
 }
 
diff --git a/source/libs/scheduler/src/scheduler.c b/source/libs/scheduler/src/scheduler.c
index fc92be8214..53ffc3bc6e 100644
--- a/source/libs/scheduler/src/scheduler.c
+++ b/source/libs/scheduler/src/scheduler.c
@@ -108,14 +108,26 @@ int32_t schedulerGetTasksStatus(int64_t jobId, SArray *pSub) {
 
   for (int32_t i = pJob->levelNum - 1; i >= 0; --i) {
     SSchLevel *pLevel = taosArrayGet(pJob->levels, i);
+    if (NULL == pLevel) {
+      qError("failed to get level %d", i);
+      SCH_ERR_JRET(TSDB_CODE_SCH_INTERNAL_ERROR);
+    }
 
     for (int32_t m = 0; m < pLevel->taskNum; ++m) {
       SSchTask     *pTask = taosArrayGet(pLevel->subTasks, m);
+      if (NULL == pTask) {
+        qError("failed to get task %d, total: %d", m, pLevel->taskNum);
+        SCH_ERR_JRET(TSDB_CODE_SCH_INTERNAL_ERROR);
+      }
+      
       SQuerySubDesc subDesc = {0};
       subDesc.tid = pTask->taskId;
       strcpy(subDesc.status, jobTaskStatusStr(pTask->status));
 
-      taosArrayPush(pSub, &subDesc);
+      if (NULL == taosArrayPush(pSub, &subDesc)) {
+        qError("taosArrayPush task %d failed, error: %x, ", m, terrno);
+        SCH_ERR_JRET(terrno);
+      }
     }
   }
 
@@ -141,7 +153,7 @@ int32_t schedulerUpdatePolicy(int32_t policy) {
       qDebug("schedule policy updated to %d", schMgmt.cfg.schPolicy);
       break;
     default:
-      return TSDB_CODE_TSC_INVALID_INPUT;
+      SCH_RET(TSDB_CODE_TSC_INVALID_INPUT);
   }
 
   return TSDB_CODE_SUCCESS;
@@ -159,14 +171,14 @@ void schedulerFreeJob(int64_t *jobId, int32_t errCode) {
 
   SSchJob *pJob = schAcquireJob(*jobId);
   if (NULL == pJob) {
-    qDebug("Acquire sch job failed, may be dropped, jobId:0x%" PRIx64, *jobId);
+    qWarn("Acquire sch job failed, may be dropped, jobId:0x%" PRIx64, *jobId);
     return;
   }
 
   SCH_JOB_DLOG("start to free job 0x%" PRIx64 ", code:%s", *jobId, tstrerror(errCode));
-  schHandleJobDrop(pJob, errCode);
+  (void)schHandleJobDrop(pJob, errCode); // ignore any error
 
-  schReleaseJob(*jobId);
+  (void)schReleaseJob(*jobId); // ignore error
   *jobId = 0;
 }
 
@@ -182,7 +194,7 @@ void schedulerDestroy(void) {
       if (refId == 0) {
         break;
       }
-      taosRemoveRef(schMgmt.jobRef, pJob->refId);
+      (void)taosRemoveRef(schMgmt.jobRef, pJob->refId); // ignore error
 
       pJob = taosIterateRef(schMgmt.jobRef, refId);
     }