Index: Python/sigcheck.c
===================================================================
--- Python/sigcheck.c	(revision 59439)
+++ Python/sigcheck.c	(working copy)
@@ -17,3 +17,6 @@
 	PyErr_SetNone(PyExc_KeyboardInterrupt);
 	return -1;
 }
+
+int Py_signal_pipe = -1;
+
Index: Include/pyerrors.h
===================================================================
--- Include/pyerrors.h	(revision 59439)
+++ Include/pyerrors.h	(working copy)
@@ -238,6 +238,11 @@
 PyAPI_FUNC(int) PyErr_CheckSignals(void);
 PyAPI_FUNC(void) PyErr_SetInterrupt(void);
 
+/* Read end of a pipe used to notify the main thread / main loop that
+   there are pending signals; Equal to -1 if the platform doesn't
+   support signals. */
+PyAPI_DATA(int) Py_signal_pipe;
+
 /* Support for adding program text to SyntaxErrors */
 PyAPI_FUNC(void) PyErr_SyntaxLocation(const char *, int);
 PyAPI_FUNC(PyObject *) PyErr_ProgramText(const char *, int);
Index: Modules/signalmodule.c
===================================================================
--- Modules/signalmodule.c	(revision 59439)
+++ Modules/signalmodule.c	(working copy)
@@ -11,6 +11,8 @@
 #endif
 
 #include <signal.h>
+#include <unistd.h>
+#include <fcntl.h>
 
 #ifndef SIG_ERR
 #define SIG_ERR ((PyOS_sighandler_t)(-1))
@@ -88,7 +90,10 @@
 
 static PyOS_sighandler_t old_siginthandler = SIG_DFL;
 
+int Py_signal_pipe = -1;        /* read end */
+static int Py_signal_pipe_w;    /* write end */
 
+
 static PyObject *
 signal_default_int_handler(PyObject *self, PyObject *args)
 {
@@ -112,6 +117,7 @@
 static void
 signal_handler(int sig_num)
 {
+	char dummy_char;
 #ifdef WITH_THREAD
 #ifdef WITH_PTH
 	if (PyThread_get_thread_ident() != main_thread) {
@@ -125,6 +131,7 @@
 		is_tripped++;
 		Handlers[sig_num].tripped = 1;
 		Py_AddPendingCall(checksignals_witharg, NULL);
+		write(Py_signal_pipe_w, &dummy_char, sizeof(dummy_char));
 #ifdef WITH_THREAD
 	}
 #endif
@@ -309,6 +316,7 @@
 {
 	PyObject *m, *d, *x;
 	int i;
+	int filedes[2], fd_flags;
 
 #ifdef WITH_THREAD
 	main_thread = PyThread_get_thread_ident();
@@ -336,6 +344,30 @@
                 goto finally;
         Py_DECREF(x);
 
+
+#define set_nonblock(fd)                                \
+	if ((fd_flags = fcntl(fd, F_GETFL, 0)) == -1) { \
+                PyErr_SetFromErrno(PyExc_RuntimeError); \
+                return;                                 \
+        }                                               \
+	fd_flags |= O_NONBLOCK;                         \
+        if (fcntl(fd, F_SETFL, fd_flags) == -1) {       \
+                PyErr_SetFromErrno(PyExc_RuntimeError); \
+                return;                                 \
+        }
+
+        if (Py_signal_pipe == -1) {
+            if (pipe(filedes)) {
+                PyErr_SetFromErrno(PyExc_RuntimeError);
+                return;
+            }
+            set_nonblock(filedes[0]);
+            set_nonblock(filedes[1]);
+            Py_signal_pipe = filedes[0];
+            Py_signal_pipe_w = filedes[1];
+        }
+#undef set_nonblock
+
 	x = IntHandler = PyDict_GetItemString(d, "default_int_handler");
         if (!x)
                 goto finally;
@@ -592,6 +624,7 @@
 int
 PyErr_CheckSignals(void)
 {
+	char dummy_c;
 	int i;
 	PyObject *f;
 
@@ -621,6 +654,11 @@
 			Py_DECREF(result);
 		}
 	}
+          /* Flush all bytes from the pipe, so that it stops notifying
+           * main threads / main loops that signals are pending. */
+	while (read(Py_signal_pipe, &dummy_c, sizeof(dummy_c)) == sizeof(dummy_c))
+		; /* pass */
+
 	is_tripped = 0;
 	return 0;
 }