feat: sleep 10ms for epoll wait

Author: jayantxie

connstate/conn_test.go

@@ -54,7 +54,7 @@ func TestListenConnState(t *testing.T) {
 	buf := make([]byte, 1)
 	_, err = conn.Read(buf)
 	assert.Equal(t, io.EOF, err)
-	time.Sleep(10 * time.Millisecond)
+	time.Sleep(100 * time.Millisecond)
 	assert.Equal(t, StateRemoteClosed, stater.State())
 	assert.Nil(t, stater.Close())
 	assert.Nil(t, conn.Close())
@@ -190,7 +190,7 @@ func BenchmarkListenConnState(b *testing.B) {
 			buf := make([]byte, 1)
 			_, err = conn.Read(buf)
 			assert.Equal(b, io.EOF, err)
-			time.Sleep(10 * time.Millisecond)
+			time.Sleep(100 * time.Millisecond)
 			assert.Equal(b, StateRemoteClosed, stater.State())
 			assert.Nil(b, stater.Close())
 			assert.Nil(b, conn.Close())

connstate/poll_bsd.go

@@ -20,6 +20,7 @@ package connstate
 import (
 	"sync/atomic"
 	"syscall"
+	"time"
 	"unsafe"
 )
 
@@ -29,15 +30,24 @@ type kqueue struct {
 
 func (p *kqueue) wait() error {
 	events := make([]syscall.Kevent_t, 1024)
+	timeout := &syscall.Timespec{Sec: 0, Nsec: 0}
+	var n int
+	var err error
 	for {
-		n, err := syscall.Kevent(p.fd, nil, events, nil)
+		// timeout=0 must be set to avoid getting stuck in a blocking syscall,
+		// which could cause a P to fail to be released in a timely manner.
+		n, err = syscall.Kevent(p.fd, nil, events, timeout)
 		if err != nil && err != syscall.EINTR {
 			// exit gracefully
 			if err == syscall.EBADF {
 				return nil
 			}
 			return err
 		}
+		if n <= 0 {
+			time.Sleep(10 * time.Millisecond) // avoid busy loop
+			continue
+		}
 		for i := 0; i < n; i++ {
 			ev := &events[i]
 			op := *(**fdOperator)(unsafe.Pointer(&ev.Udata))

connstate/poll_linux.go

@@ -17,9 +17,8 @@ package connstate
 import (
 	"sync/atomic"
 	"syscall"
+	"time"
 	"unsafe"
-
-	isyscall "github.com/cloudwego/gopkg/internal/syscall"
 )
 
 const _EPOLLET uint32 = 0x80000000
@@ -31,13 +30,19 @@ type epoller struct {
 //go:nocheckptr
 func (p *epoller) wait() error {
 	events := make([]syscall.EpollEvent, 1024)
+	var n int
+	var err error
 	for {
-		// epoll wait is a blocking syscall, so we need to call entersyscallblock to handoff P,
-		// and let the P run other goroutines.
-		n, err := isyscall.EpollWait(p.epfd, events, -1)
+		// timeout=0 must be set to avoid getting stuck in a blocking syscall,
+		// which could cause a P to fail to be released in a timely manner.
+		n, err = syscall.EpollWait(p.epfd, events, 0)
 		if err != nil && err != syscall.EINTR {
 			return err
 		}
+		if n <= 0 {
+			time.Sleep(10 * time.Millisecond) // avoid busy loop
+			continue
+		}
 		for i := 0; i < n; i++ {
 			ev := &events[i]
 			op := *(**fdOperator)(unsafe.Pointer(&ev.Fd))