[TD-2379]<enhance>: configure the number of CPU cores available for query processing.

packaging/cfg/taos.cfg

@@ -30,10 +30,11 @@
 # numOfThreadsPerCore       1.0
 
 # the proportion of total CPU cores available for query processing
-# 1.0: all CPU cores are available for query processing
-# 0.5: only half of the CPU cores are available for query
-# 0.0: only one core available
-# ratioOfQueryThreads       1.0
+# 2.0: the query threads will be set to double of the CPU cores.
+# 1.0: all CPU cores are available for query processing [default].
+# 0.5: only half of the CPU cores are available for query.
+# 0.0: only one core available.
+# tsRatioOfQueryCores       1.0
 
 # number of management nodes in the system
 # numOfMnodes               3

src/common/inc/tglobal.h

@@ -46,7 +46,7 @@ extern int32_t  tsShellActivityTimer;
 extern uint32_t tsMaxTmrCtrl;
 extern float    tsNumOfThreadsPerCore;
 extern int32_t  tsNumOfCommitThreads;
-extern float    tsRatioOfQueryThreads;
+extern float    tsRatioOfQueryCores;
 extern int8_t   tsDaylight;
 extern char     tsTimezone[];
 extern char     tsLocale[];

src/common/src/tglobal.c

@@ -52,7 +52,7 @@ int32_t tsMaxConnections = 5000;
 int32_t tsShellActivityTimer  = 3;  // second
 float   tsNumOfThreadsPerCore = 1.0f;
 int32_t tsNumOfCommitThreads = 1;
-float   tsRatioOfQueryThreads = 1.0f;
+float   tsRatioOfQueryCores = 1.0f;
 int8_t  tsDaylight       = 0;
 char    tsTimezone[TSDB_TIMEZONE_LEN] = {0};
 char    tsLocale[TSDB_LOCALE_LEN] = {0};
@@ -444,12 +444,12 @@ static void doInitGlobalConfig(void) {
   cfg.unitType = TAOS_CFG_UTYPE_NONE;
   taosInitConfigOption(cfg);
 
-  cfg.option = "ratioOfQueryThreads";
-  cfg.ptr = &tsRatioOfQueryThreads;
+  cfg.option = "ratioOfQueryCores";
+  cfg.ptr = &tsRatioOfQueryCores;
   cfg.valType = TAOS_CFG_VTYPE_FLOAT;
   cfg.cfgType = TSDB_CFG_CTYPE_B_CONFIG;
-  cfg.minValue = 0.1f;
-  cfg.maxValue = 0.9f;
+  cfg.minValue = 0.0f;
+  cfg.maxValue = 2.0f;
   cfg.ptrLength = 0;
   cfg.unitType = TAOS_CFG_UTYPE_NONE;
   taosInitConfigOption(cfg);

src/dnode/src/dnodeVRead.c

@@ -28,9 +28,12 @@ static SWorkerPool tsVFetchWP;
 int32_t dnodeInitVRead() {
   const int32_t maxFetchThreads = 4;
 
+  // calculate the available query thread
+  float threadsForQuery = MAX(tsNumOfCores * tsRatioOfQueryCores, 1);
+
   tsVQueryWP.name = "vquery";
   tsVQueryWP.workerFp = dnodeProcessReadQueue;
-  tsVQueryWP.min = tsNumOfCores * tsRatioOfQueryThreads;
+  tsVQueryWP.min = (int32_t) threadsForQuery;
   tsVQueryWP.max = tsVQueryWP.min;
   if (tWorkerInit(&tsVQueryWP) != 0) return -1;