def _set_cloexec(self):
        """Set the CLOEXEC flag on all open files (except stdin/out/err).

        If self.max_cloexec_files is an integer (the default), then on
        platforms which support it, it represents the max open files
        setting for the operating system. This function will be called
        just before the process is restarted via os.execv() to prevent
        open files from persisting into the new process.

        Set self.max_cloexec_files to 0 to disable this behavior.
        """
        for fd in range(3, self.max_cloexec_files):  # skip stdin/out/err
            try:
                flags = fcntl.fcntl(fd, fcntl.F_GETFD)
            except IOError:
                continue
            fcntl.fcntl(fd, fcntl.F_SETFD, flags | fcntl.FD_CLOEXEC)
Set the CLOEXEC flag on all open files (except stdin/out/err).

        If self.max_cloexec_files is an integer (the default), then on
        platforms which support it, it represents the max open files
        setting for the operating system. This function will be called
        just before the process is restarted via os.execv() to prevent
        open files from persisting into the new process.

        Set self.max_cloexec_files to 0 to disable this behavior.
        
cherrypy/process/wspbus.py