Improve socket bind verification and PID file retry handling in process supervisor

Author: vikrezdev

internal/supervisor/supervisor.go

@@ -526,16 +526,20 @@ func (s *Supervisor) startNginx() (ServiceStatus, error) {
 }
 
 func readPIDFile(path string) int {
-	data, err := os.ReadFile(path)
-	if err != nil {
-		return 0
+	for i := 0; i < 10; i++ {
+		data, err := os.ReadFile(path)
+		if err == nil {
+			if pid, _ := strconv.Atoi(strings.TrimSpace(string(data))); pid > 0 {
+				return pid
+			}
+		}
+		time.Sleep(100 * time.Millisecond)
 	}
-	pid, _ := strconv.Atoi(strings.TrimSpace(string(data)))
-	return pid
+	return 0
 }
 
 func (s *Supervisor) startPHPCGI(port int) error {
-	if existing := s.State.RunningPIDs["php-cgi"]; existing != 0 && IsProcessRunning(existing) {
+	if existing := s.State.RunningPIDs["php-cgi"]; existing != 0 && IsProcessRunning(existing) && isPortBound(port) {
 		return nil
 	}
 	logFile, err := os.OpenFile(filepath.Join(s.LogDir, "php-cgi.log"), os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)