enhance robustness of scheduler

1. check all memory allocation failure in `taosInitScheduler`;
2. make `pSched->numOfThreads` the actual number of created threads
to avoid crash in `taosCleanUpScheduler` when `pSched->qthread` is NULL
and other issues;
3. check interruption of `sem_wait` in `taosScheduleTask`,
and use `pTrace` instead of `pError` when `sem_wait` was interrupted;
4. cancel all threads before join them to enable cocurrent cancellation;
5. remove unused global variable.

src/util/src/tsched.c

@@ -38,17 +38,19 @@ typedef struct {
   SSchedMsg *     queue;
 } SSchedQueue;
 
-void (*taosSchedFp[128])(SSchedMsg *msg) = {0};
 void *taosProcessSchedQueue(void *param);
 void taosCleanUpScheduler(void *param);
 
 void *taosInitScheduler(int queueSize, int numOfThreads, const char *label) {
   pthread_attr_t attr;
   SSchedQueue *  pSched = (SSchedQueue *)malloc(sizeof(SSchedQueue));
+  if (pSched == NULL) {
+    pError("%s: no enough memory for pSched, reason: %s", label, strerror(errno));
+    goto _error;
+  }
 
   memset(pSched, 0, sizeof(SSchedQueue));
   pSched->queueSize = queueSize;
-  pSched->numOfThreads = numOfThreads;
   strncpy(pSched->label, label, sizeof(pSched->label)); // fix buffer overflow
   pSched->label[sizeof(pSched->label)-1] = '\0';
 
@@ -76,16 +78,21 @@ void *taosInitScheduler(int queueSize, int numOfThreads, const char *label) {
   pSched->fullSlot = 0;
   pSched->emptySlot = 0;
 
-  pSched->qthread = malloc(sizeof(pthread_t) * (size_t)pSched->numOfThreads);
+  pSched->qthread = malloc(sizeof(pthread_t) * (size_t)numOfThreads);
+  if (pSched->qthread == NULL) {
+    pError("%s: no enough memory for qthread, reason: %s", pSched->label, strerror(errno));
+    goto _error;
+  }
 
   pthread_attr_init(&attr);
   pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
 
-  for (int i = 0; i < pSched->numOfThreads; ++i) {
+  for (int i = 0; i < numOfThreads; ++i) {
     if (pthread_create(pSched->qthread + i, &attr, taosProcessSchedQueue, (void *)pSched) != 0) {
       pError("%s: failed to create rpc thread, reason:%s", pSched->label, strerror(errno));
       goto _error;
     }
+    ++pSched->numOfThreads;
   }
 
   pTrace("%s scheduler is initialized, numOfThreads:%d", pSched->label, pSched->numOfThreads);
@@ -103,11 +110,12 @@ void *taosProcessSchedQueue(void *param) {
 
   while (1) {
     if (sem_wait(&pSched->fullSem) != 0) {
-      pError("wait %s fullSem failed, errno:%d, reason:%s", pSched->label, errno, strerror(errno));
       if (errno == EINTR) {
         /* sem_wait is interrupted by interrupt, ignore and continue */
+        pTrace("wait %s fullSem was interrupted", pSched->label);
         continue;
       }
+      pError("wait %s fullSem failed, errno:%d, reason:%s", pSched->label, errno, strerror(errno));
     }
 
     if (pthread_mutex_lock(&pSched->queueMutex) != 0)
@@ -137,7 +145,13 @@ int taosScheduleTask(void *qhandle, SSchedMsg *pMsg) {
     return 0;
   }
 
-  if (sem_wait(&pSched->emptySem) != 0) pError("wait %s emptySem failed, reason:%s", pSched->label, strerror(errno));
+  while (sem_wait(&pSched->emptySem) != 0) {
+    if (errno != EINTR) {
+      pError("wait %s emptySem failed, reason:%s", pSched->label, strerror(errno));
+      break;
+    }
+    pTrace("wait %s emptySem was interrupted", pSched->label);
+  }
 
   if (pthread_mutex_lock(&pSched->queueMutex) != 0)
     pError("lock %s queueMutex failed, reason:%s", pSched->label, strerror(errno));
@@ -159,6 +173,8 @@ void taosCleanUpScheduler(void *param) {
 
   for (int i = 0; i < pSched->numOfThreads; ++i) {
     pthread_cancel(pSched->qthread[i]);
+  }
+  for (int i = 0; i < pSched->numOfThreads; ++i) {
     pthread_join(pSched->qthread[i], NULL);
   }