@ysc3839 do {
Py_BEGIN_ALLOW_THREADS
ret = fcntl(fd, code, buf);
Py_END_ALLOW_THREADS
} while (ret == -1 && errno == EINTR && !(async_err = PyErr_CheckSignals()));

能否解释下，感觉只看懂了线程开始和结束，循环 fcntl 是否结束