diff --git a/internal/querynodev2/tasks/scheduler.go b/internal/querynodev2/tasks/scheduler.go
index 404d5aea8c21bf1a1afec5e5c0f27468285efe46..fd78c98034af523c8a65a453214a2d11c3aa05da 100644
--- a/internal/querynodev2/tasks/scheduler.go
+++ b/internal/querynodev2/tasks/scheduler.go
@@ -3,6 +3,7 @@ package tasks
 import (
 	"context"
 	"fmt"
+	"sync"
 
 	"go.uber.org/atomic"
 
@@ -25,7 +26,9 @@ type Scheduler struct {
 	queryProcessQueue chan *QueryTask
 	queryWaitQueue    chan *QueryTask
 
-	pool *conc.Pool[any]
+	pool             *conc.Pool[any]
+	runningThreadNum int
+	cond             *sync.Cond
 }
 
 func NewScheduler() *Scheduler {
@@ -39,6 +42,7 @@ func NewScheduler() *Scheduler {
 		// queryProcessQueue: make(chan),
 
 		pool: conc.NewPool[any](maxReadConcurrency, ants.WithPreAlloc(true)),
+		cond: sync.NewCond(&sync.Mutex{}),
 	}
 }
 
@@ -151,7 +155,23 @@ func (s *Scheduler) processAll(ctx context.Context) {
 }
 
 func (s *Scheduler) process(t Task) {
+	s.cond.L.Lock()
+	for s.runningThreadNum >= s.pool.Cap() {
+		s.cond.Wait()
+	}
+	s.runningThreadNum += t.Weight()
+	s.cond.L.Unlock()
+
 	s.pool.Submit(func() (any, error) {
+		defer func() {
+			s.cond.L.Lock()
+			defer s.cond.L.Unlock()
+			s.runningThreadNum -= t.Weight()
+			if s.runningThreadNum < s.pool.Cap() {
+				s.cond.Broadcast()
+			}
+		}()
+
 		metrics.QueryNodeReadTaskConcurrency.WithLabelValues(fmt.Sprint(paramtable.GetNodeID())).Inc()
 
 		err := t.Execute()
diff --git a/internal/querynodev2/tasks/task.go b/internal/querynodev2/tasks/task.go
index cc1f5f5d8904dccb864e80450a7b9bc88891af34..322e08b35f29f0204134847f3d42c32c25c378f4 100644
--- a/internal/querynodev2/tasks/task.go
+++ b/internal/querynodev2/tasks/task.go
@@ -25,6 +25,7 @@ type Task interface {
 	Done(err error)
 	Canceled() error
 	Wait() error
+	Weight() int
 }
 
 type SearchTask struct {
@@ -235,6 +236,10 @@ func (t *SearchTask) Wait() error {
 	return <-t.notifier
 }
 
+func (t *SearchTask) Weight() int {
+	return int(t.nq)
+}
+
 func (t *SearchTask) Result() *internalpb.SearchResults {
 	return t.result
 }