Python 信号机制

import signal

def signalHandler(num,frame):
pass
signal.signal(signal.SIGTERM,signalHandler)

http://guozhiwei.iteye.com/blog/939008
http://www.sugarsfree.org/?p=179

信号触发: signal_handler-->Py_AddPendingCall-->Py_MakePendingCalls-->checksignals_witharg-->PyErr_CheckSignals

static PyObject *
signal_signal(PyObject *self, PyObject *args)
{
PyObject *obj;
int sig_num;
PyObject *old_handler;
void (*func)(int);
if (!PyArg_ParseTuple(args, "iO:signal", &sig_num, &obj))
return NULL;
#ifdef WITH_THREAD
if (PyThread_get_thread_ident() != main_thread) {
PyErr_SetString(PyExc_ValueError,
"signal only works in main thread");
return NULL;
}
#endif
if (sig_num < 1 || sig_num >= NSIG) {
PyErr_SetString(PyExc_ValueError,
"signal number out of range");
return NULL;
}
if (obj == IgnoreHandler)
func = SIG_IGN;
else if (obj == DefaultHandler)
func = SIG_DFL;
else if (!PyCallable_Check(obj)) {
PyErr_SetString(PyExc_TypeError,
"signal handler must be signal.SIG_IGN, signal.SIG_DFL, or a callable object");
return NULL;
}
else
func = signal_handler; ——>注意signal_handler
if (PyOS_setsig(sig_num, func) == SIG_ERR) {
PyErr_SetFromErrno(PyExc_RuntimeError);
return NULL;
}
old_handler = Handlers[sig_num].func;
Handlers[sig_num].tripped = 0;
Py_INCREF(obj);
Handlers[sig_num].func = obj;
return old_handler;
}


static void
signal_handler(int sig_num)
{
#ifdef WITH_THREAD
#ifdef WITH_PTH
if (PyThread_get_thread_ident() != main_thread) {
pth_raise(*(pth_t *) main_thread, sig_num);
return;
}
#endif
/* See NOTES section above */
if (getpid() == main_pid) {
#endif
Handlers[sig_num].tripped = 1;
/* Set is_tripped after setting .tripped, as it gets
cleared in PyErr_CheckSignals() before .tripped. */
is_tripped = 1;
Py_AddPendingCall(checksignals_witharg, NULL); ——>关注Py_AddPendingCall
#ifdef WITH_THREAD
}
#endif
#ifdef SIGCHLD
if (sig_num == SIGCHLD) {
/* To avoid infinite recursion, this signal remains
reset until explicit re-instated.
Don't clear the 'func' field as it is our pointer
to the Python handler... */
return;
}
#endif
PyOS_setsig(sig_num, signal_handler);
}

位于Modules/signalmodule.c
http://magicode.me/index.php/2011/12/python-%E4%BF%A1%E5%8F%B7%E6%9C%BA%E5%88%B6%E6%B7%B1%E5%85%A5%E5%AD%A6%E4%B9%A0/
http://blog.csdn.net/piaomiao245285/article/details/6278404