diff --git a/.github/workflows/pr-check.yml b/.github/workflows/pr-check.yml
index d61d604b..a923b418 100644
--- a/.github/workflows/pr-check.yml
+++ b/.github/workflows/pr-check.yml
@@ -1,12 +1,12 @@
 name: Push and Pull Request Check
 
-on: [ push ]
+on: [ push, pull_request ]
 
 jobs:
   compatibility-test:
     strategy:
       matrix:
-        go: [ 1.15, "1.20" ]
+        go: [ 1.15, "1.21" ]
         os: [ X64, ARM64 ]
     runs-on: ${{ matrix.os }}
     steps:
diff --git a/connection_onevent.go b/connection_onevent.go
index 6ddbf31e..9b87f01b 100644
--- a/connection_onevent.go
+++ b/connection_onevent.go
@@ -195,13 +195,26 @@ func (c *connection) onProcess(isProcessable func(c *connection) bool, process f
 		if isProcessable(c) {
 			process(c)
 		}
-		for !c.isCloseBy(user) && isProcessable(c) {
+		// `process` must either eventually read all the input data or actively Close the connection,
+		// otherwise the goroutine will fall into a dead loop.
+		var closedBy who
+		for {
+			closedBy = c.status(closing)
+			// close by user or no processable
+			if closedBy == user || !isProcessable(c) {
+				break
+			}
 			process(c)
 		}
 		// Handling callback if connection has been closed.
-		if !c.IsActive() {
-			// connection if closed by user when processing, so it needs detach
-			c.closeCallback(false, true)
+		if closedBy != none {
+			//  if closed by user when processing, it "may" needs detach
+			needDetach := closedBy == user
+			// Here is a conor case that operator will be detached twice:
+			//   If server closed the connection(client OnHup will detach op first and closeBy=poller),
+			//   and then client's OnRequest function also closed the connection(closeBy=user).
+			// But operator already prevent that detach twice will not cause any problem
+			c.closeCallback(false, needDetach)
 			panicked = false
 			return
 		}
@@ -229,7 +242,7 @@ func (c *connection) closeCallback(needLock bool, needDetach bool) (err error) {
 	if needDetach && c.operator.poll != nil { // If Close is called during OnPrepare, poll is not registered.
 		// PollDetach only happen when user call conn.Close() or poller detect error
 		if err := c.operator.Control(PollDetach); err != nil {
-			logger.Printf("NETPOLL: onClose detach operator failed: %v", err)
+			logger.Printf("NETPOLL: closeCallback[%v,%v] detach operator failed: %v", needLock, needDetach, err)
 		}
 	}
 	var latest = c.closeCallbacks.Load()
diff --git a/connection_reactor.go b/connection_reactor.go
index 2acd45ce..fa485be1 100644
--- a/connection_reactor.go
+++ b/connection_reactor.go
@@ -31,11 +31,12 @@ func (c *connection) onHup(p Poll) error {
 	c.triggerRead(Exception(ErrEOF, "peer close"))
 	c.triggerWrite(Exception(ErrConnClosed, "peer close"))
 	// It depends on closing by user if OnConnect and OnRequest is nil, otherwise it needs to be released actively.
-	// It can be confirmed that the OnRequest goroutine has been exited before closecallback executing,
+	// It can be confirmed that the OnRequest goroutine has been exited before closeCallback executing,
 	// and it is safe to close the buffer at this time.
-	var onConnect, _ = c.onConnectCallback.Load().(OnConnect)
-	var onRequest, _ = c.onRequestCallback.Load().(OnRequest)
-	if onConnect != nil || onRequest != nil {
+	var onConnect = c.onConnectCallback.Load()
+	var onRequest = c.onRequestCallback.Load()
+	var needCloseByUser = onConnect == nil && onRequest == nil
+	if !needCloseByUser {
 		// already PollDetach when call OnHup
 		c.closeCallback(true, false)
 	}
diff --git a/connection_test.go b/connection_test.go
index ec72a0c9..6de6f017 100644
--- a/connection_test.go
+++ b/connection_test.go
@@ -540,3 +540,101 @@ func TestParallelShortConnection(t *testing.T) {
 		time.Sleep(time.Millisecond * 100)
 	}
 }
+
+func TestConnectionServerClose(t *testing.T) {
+	ln, err := createTestListener("tcp", ":12345")
+	MustNil(t, err)
+	defer ln.Close()
+
+	/*
+		Client              Server
+		- Client --- connect   --> Server
+		- Client <-- [ping]   --- Server
+		- Client --- [pong]   --> Server
+		- Client <-- close     --- Server
+		- Client --- close     --> Server
+	*/
+	const PING, PONG = "ping", "pong"
+	var wg sync.WaitGroup
+	el, err := NewEventLoop(
+		func(ctx context.Context, connection Connection) error {
+			t.Logf("server.OnRequest: addr=%s", connection.RemoteAddr())
+			defer wg.Done()
+			buf, err := connection.Reader().Next(len(PONG)) // pong
+			Equal(t, string(buf), PONG)
+			MustNil(t, err)
+			err = connection.Reader().Release()
+			MustNil(t, err)
+			err = connection.Close()
+			MustNil(t, err)
+			return err
+		},
+		WithOnConnect(func(ctx context.Context, connection Connection) context.Context {
+			t.Logf("server.OnConnect: addr=%s", connection.RemoteAddr())
+			defer wg.Done()
+			// check OnPrepare
+			v := ctx.Value("prepare").(string)
+			Equal(t, v, "true")
+
+			_, err := connection.Writer().WriteBinary([]byte(PING))
+			MustNil(t, err)
+			err = connection.Writer().Flush()
+			MustNil(t, err)
+			connection.AddCloseCallback(func(connection Connection) error {
+				t.Logf("server.CloseCallback: addr=%s", connection.RemoteAddr())
+				wg.Done()
+				return nil
+			})
+			return ctx
+		}),
+		WithOnPrepare(func(connection Connection) context.Context {
+			t.Logf("server.OnPrepare: addr=%s", connection.RemoteAddr())
+			defer wg.Done()
+			return context.WithValue(context.Background(), "prepare", "true")
+		}),
+	)
+	defer el.Shutdown(context.Background())
+	go func() {
+		err := el.Serve(ln)
+		if err != nil {
+			t.Logf("servce end with error: %v", err)
+		}
+	}()
+
+	var clientOnRequest OnRequest = func(ctx context.Context, connection Connection) error {
+		t.Logf("client.OnRequest: addr=%s", connection.LocalAddr())
+		defer wg.Done()
+		buf, err := connection.Reader().Next(len(PING))
+		MustNil(t, err)
+		Equal(t, string(buf), PING)
+
+		_, err = connection.Writer().WriteBinary([]byte(PONG))
+		MustNil(t, err)
+		err = connection.Writer().Flush()
+		MustNil(t, err)
+
+		_, err = connection.Reader().Next(1) // server will not send any data, just wait for server close
+		MustTrue(t, errors.Is(err, ErrEOF))  // should get EOF when server close
+
+		return connection.Close()
+	}
+	conns := 100
+	// server: OnPrepare, OnConnect, OnRequest, CloseCallback
+	// client: OnRequest, CloseCallback
+	wg.Add(conns * 6)
+	for i := 0; i < conns; i++ {
+		go func() {
+			conn, err := DialConnection("tcp", ":12345", time.Second)
+			MustNil(t, err)
+			err = conn.SetOnRequest(clientOnRequest)
+			MustNil(t, err)
+			conn.AddCloseCallback(func(connection Connection) error {
+				t.Logf("client.CloseCallback: addr=%s", connection.LocalAddr())
+				defer wg.Done()
+				return nil
+			})
+		}()
+	}
+	//time.Sleep(time.Second)
+	wg.Wait()
+}
diff --git a/fd_operator.go b/fd_operator.go
index 4132fe9c..1ac843a9 100644
--- a/fd_operator.go
+++ b/fd_operator.go
@@ -42,6 +42,9 @@ type FDOperator struct {
 	// poll is the registered location of the file descriptor.
 	poll Poll
 
+	// protect only detach once
+	detached int32
+
 	// private, used by operatorCache
 	next  *FDOperator
 	state int32 // CAS: 0(unused) 1(inuse) 2(do-done)
@@ -49,6 +52,9 @@ type FDOperator struct {
 }
 
 func (op *FDOperator) Control(event PollEvent) error {
+	if event == PollDetach && atomic.AddInt32(&op.detached, 1) > 1 {
+		return nil
+	}
 	return op.poll.Control(op, event)
 }
 
@@ -92,4 +98,5 @@ func (op *FDOperator) reset() {
 	op.Inputs, op.InputAck = nil, nil
 	op.Outputs, op.OutputAck = nil, nil
 	op.poll = nil
+	op.detached = 0
 }
diff --git a/nocopy_linkbuffer.go b/nocopy_linkbuffer.go
index 59cc6530..555ba5ce 100644
--- a/nocopy_linkbuffer.go
+++ b/nocopy_linkbuffer.go
@@ -461,9 +461,8 @@ func (b *LinkBuffer) WriteBinary(p []byte) (n int, err error) {
 	}
 	// here will copy
 	b.growth(n)
-	malloc := b.write.malloc
-	b.write.malloc += n
-	return copy(b.write.buf[malloc:b.write.malloc], p), nil
+	buf := b.write.Malloc(n)
+	return copy(buf, p), nil
 }
 
 // WriteDirect cannot be mixed with WriteString or WriteBinary functions.
@@ -578,7 +577,8 @@ func (b *LinkBuffer) GetBytes(p [][]byte) (vs [][]byte) {
 //
 // bookSize: The size of data that can be read at once.
 // maxSize: The maximum size of data between two Release(). In some cases, this can
-// 	guarantee all data allocated in one node to reduce copy.
+//
+//	guarantee all data allocated in one node to reduce copy.
 func (b *LinkBuffer) book(bookSize, maxSize int) (p []byte) {
 	l := cap(b.write.buf) - b.write.malloc
 	// grow linkBuffer
diff --git a/nocopy_linkbuffer_race.go b/nocopy_linkbuffer_race.go
index a785aa15..4b3635d0 100644
--- a/nocopy_linkbuffer_race.go
+++ b/nocopy_linkbuffer_race.go
@@ -497,9 +497,8 @@ func (b *LinkBuffer) WriteBinary(p []byte) (n int, err error) {
 	}
 	// here will copy
 	b.growth(n)
-	malloc := b.write.malloc
-	b.write.malloc += n
-	return copy(b.write.buf[malloc:b.write.malloc], p), nil
+	buf := b.write.Malloc(n)
+	return copy(buf, p), nil
 }
 
 // WriteDirect cannot be mixed with WriteString or WriteBinary functions.
@@ -622,7 +621,8 @@ func (b *LinkBuffer) GetBytes(p [][]byte) (vs [][]byte) {
 //
 // bookSize: The size of data that can be read at once.
 // maxSize: The maximum size of data between two Release(). In some cases, this can
-// 	guarantee all data allocated in one node to reduce copy.
+//
+//	guarantee all data allocated in one node to reduce copy.
 func (b *LinkBuffer) book(bookSize, maxSize int) (p []byte) {
 	b.Lock()
 	defer b.Unlock()