diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index 06308f9e0cba1c3a4586c10c574b826baad2dc6c..97b7fb0a5abbbb2eca0e46d2a07d39e85d5d5e6a 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -841,6 +841,11 @@ static int32_t tscEstimateQueryMsgSize(SSqlObj *pSql) {
     tableSerialize = totalTables * sizeof(STableIdInfo);
   }
 
+  SCond* pCond = &pQueryInfo->tagCond.tbnameCond;
+  if (pCond->len > 0) {
+    srcColListSize += pCond->len;
+  }
+
   return MIN_QUERY_MSG_PKT_SIZE + minMsgSize() + sizeof(SQueryTableMsg) + srcColListSize + srcColFilterSize + srcTagFilterSize +
          exprSize + tsBufSize + tableSerialize + sqlLen + 4096 + pQueryInfo->bufLen;
 }
diff --git a/src/client/src/tscSubquery.c b/src/client/src/tscSubquery.c
index 816347cecdedc572b0872769e7a84a94986df9f0..3314798d6d9599ae1db72d4a84e08b56ecff9e08 100644
--- a/src/client/src/tscSubquery.c
+++ b/src/client/src/tscSubquery.c
@@ -15,8 +15,9 @@
 #define _GNU_SOURCE
 
 #include "os.h"
-
 #include "texpr.h"
+
+#include "tsched.h"
 #include "qTsbuf.h"
 #include "tcompare.h"
 #include "tscLog.h"
@@ -2425,6 +2426,26 @@ int32_t tscHandleFirstRoundStableQuery(SSqlObj *pSql) {
   return terrno;
 }
 
+typedef struct SPair {
+  int32_t first;
+  int32_t second;
+} SPair;
+
+static void doSendQueryReqs(SSchedMsg* pSchedMsg) {
+  SSqlObj* pSql = pSchedMsg->ahandle;
+  SPair* p = pSchedMsg->msg;
+
+  for(int32_t i = p->first; i < p->second; ++i) {
+    SSqlObj* pSub = pSql->pSubs[i];
+    SRetrieveSupport* pSupport = pSub->param;
+
+    tscDebug("0x%"PRIx64" sub:0x%"PRIx64" launch subquery, orderOfSub:%d.", pSql->self, pSub->self, pSupport->subqueryIndex);
+    tscProcessSql(pSub);
+  }
+
+  tfree(p);
+}
+
 int32_t tscHandleMasterSTableQuery(SSqlObj *pSql) {
   SSqlRes *pRes = &pSql->res;
   SSqlCmd *pCmd = &pSql->cmd;
@@ -2547,13 +2568,33 @@ int32_t tscHandleMasterSTableQuery(SSqlObj *pSql) {
     doCleanupSubqueries(pSql, i);
     return pRes->code;
   }
-  
-  for(int32_t j = 0; j < pState->numOfSub; ++j) {
-    SSqlObj* pSub = pSql->pSubs[j];
-    SRetrieveSupport* pSupport = pSub->param;
-    
-    tscDebug("0x%"PRIx64" sub:0x%"PRIx64" launch subquery, orderOfSub:%d.", pSql->self, pSub->self, pSupport->subqueryIndex);
-    tscBuildAndSendRequest(pSub, NULL);
+
+  // concurrently sent the query requests.
+  const int32_t MAX_REQUEST_PER_TASK = 8;
+
+  int32_t numOfTasks = (pState->numOfSub + MAX_REQUEST_PER_TASK - 1)/MAX_REQUEST_PER_TASK;
+  assert(numOfTasks >= 1);
+
+  int32_t num = (pState->numOfSub/numOfTasks) + 1;
+  tscDebug("0x%"PRIx64 " query will be sent by %d threads", pSql->self, numOfTasks);
+
+  for(int32_t j = 0; j < numOfTasks; ++j) {
+    SSchedMsg schedMsg = {0};
+    schedMsg.fp      = doSendQueryReqs;
+    schedMsg.ahandle = (void*)pSql;
+
+    schedMsg.thandle = NULL;
+    SPair* p = calloc(1, sizeof(SPair));
+    p->first  = j * num;
+
+    if (j == numOfTasks - 1) {
+      p->second = pState->numOfSub;
+    } else {
+      p->second = (j + 1) * num;
+    }
+
+    schedMsg.msg = p;
+    taosScheduleTask(tscQhandle, &schedMsg);
   }
 
   return TSDB_CODE_SUCCESS;
diff --git a/src/connector/python/examples/demo.py b/src/connector/python/examples/demo.py
index 6c7c03f3e2c9630fab2af661d5c589066c21755f..3bc09046f3a33557e513425c06373c66958f2a2f 100644
--- a/src/connector/python/examples/demo.py
+++ b/src/connector/python/examples/demo.py
@@ -2,7 +2,7 @@ import taos
 
 conn = taos.connect(host='127.0.0.1',
                     user='root',
-                    passworkd='taodata',
+                    password='taosdata',
                     database='log')
 cursor = conn.cursor()
 
diff --git a/src/os/src/linux/linuxEnv.c b/src/os/src/linux/linuxEnv.c
index b7b268b19e6b6f92babb74cfd3f23793be037cd0..650a45aae42c8d2dfba63d8f4e7e6ec35b385ae8 100644
--- a/src/os/src/linux/linuxEnv.c
+++ b/src/os/src/linux/linuxEnv.c
@@ -50,14 +50,20 @@ void osInit() {
 char* taosGetCmdlineByPID(int pid) {
   static char cmdline[1024];
   sprintf(cmdline, "/proc/%d/cmdline", pid);
-  FILE* f = fopen(cmdline, "r");
-  if (f) {
-    size_t size;
-    size = fread(cmdline, sizeof(char), 1024, f);
-    if (size > 0) {
-      if ('\n' == cmdline[size - 1]) cmdline[size - 1] = '\0';
-    }
-    fclose(f);
+
+  int fd = open(cmdline, O_RDONLY);
+  if (fd >= 0) {
+    int n = read(fd, cmdline, sizeof(cmdline) - 1);
+    if (n < 0) n = 0;
+
+    if (n > 0 && cmdline[n - 1] == '\n') --n;
+
+    cmdline[n] = 0;
+
+    close(fd);
+  } else {
+    cmdline[0] = 0;
   }
+
   return cmdline;
 }
diff --git a/src/query/src/qAggMain.c b/src/query/src/qAggMain.c
index 15877465870872870d5be76addce34ccbd366e79..9019a01eeff87414e917923666d2e4d842e3d12c 100644
--- a/src/query/src/qAggMain.c
+++ b/src/query/src/qAggMain.c
@@ -4089,7 +4089,7 @@ static void mergeTableBlockDist(SResultRowCellInfo* pResInfo, const STableBlockD
   } else {
     pDist->maxRows = pSrc->maxRows;
     pDist->minRows = pSrc->minRows;
-    
+
     int32_t maxSteps = TSDB_MAX_MAX_ROW_FBLOCK/TSDB_BLOCK_DIST_STEP_ROWS;
     if (TSDB_MAX_MAX_ROW_FBLOCK % TSDB_BLOCK_DIST_STEP_ROWS != 0) {
       ++maxSteps;
@@ -4223,7 +4223,7 @@ void blockinfo_func_finalizer(SQLFunctionCtx* pCtx) {
     taosArrayDestroy(pDist->dataBlockInfos);
     pDist->dataBlockInfos = NULL;
   }
-  
+
   // cannot set the numOfIteratedElems again since it is set during previous iteration
   pResInfo->numOfRes  = 1;
   pResInfo->hasResult = DATA_SET_FLAG;
diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 26ae714c27838d505996908c4cc05078e08c79ae..e55c798a02af588044b9a130f5a3d0aafdfb2ea3 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -7449,10 +7449,12 @@ int32_t convertQueryMsg(SQueryTableMsg *pQueryMsg, SQueryParam* param) {
   pQueryMsg->numOfOutput = htons(pQueryMsg->numOfOutput);
   pQueryMsg->numOfGroupCols = htons(pQueryMsg->numOfGroupCols);
   pQueryMsg->tagCondLen = htonl(pQueryMsg->tagCondLen);
+
   pQueryMsg->tsBuf.tsOffset = htonl(pQueryMsg->tsBuf.tsOffset);
   pQueryMsg->tsBuf.tsLen = htonl(pQueryMsg->tsBuf.tsLen);
   pQueryMsg->tsBuf.tsNumOfBlocks = htonl(pQueryMsg->tsBuf.tsNumOfBlocks);
   pQueryMsg->tsBuf.tsOrder = htonl(pQueryMsg->tsBuf.tsOrder);
+
   pQueryMsg->numOfTags = htonl(pQueryMsg->numOfTags);
   pQueryMsg->tbnameCondLen = htonl(pQueryMsg->tbnameCondLen);
   pQueryMsg->secondStageOutput = htonl(pQueryMsg->secondStageOutput);
diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index 524ab065d693b9a80643c1085402a6d9b1740824..fe5ad89312becfac1d08a663057805c8667b52bc 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -2460,7 +2460,7 @@ int32_t tsdbGetFileBlocksDistInfo(TsdbQueryHandleT* queryHandle, STableBlockDist
 
     // current file are not overlapped with query time window, ignore remain files
     if ((ASCENDING_TRAVERSE(pQueryHandle->order) && win.skey > pQueryHandle->window.ekey) ||
-        (!ASCENDING_TRAVERSE(pQueryHandle->order) && win.ekey < pQueryHandle->window.ekey)) {
+    (!ASCENDING_TRAVERSE(pQueryHandle->order) && win.ekey < pQueryHandle->window.ekey)) {
       tsdbUnLockFS(REPO_FS(pQueryHandle->pTsdb));
       tsdbDebug("%p remain files are not qualified for qrange:%" PRId64 "-%" PRId64 ", ignore, 0x%"PRIx64, pQueryHandle,
                 pQueryHandle->window.skey, pQueryHandle->window.ekey, pQueryHandle->qId);