Ignoring EEXIST in epoll hub on register. Should fix eventlet#80.

eventlet/hubs/epolls.py

@@ -44,11 +44,15 @@ def add(self, evtype, fileno, cb):
         oldlisteners = bool(self.listeners[READ].get(fileno) or
                             self.listeners[WRITE].get(fileno))
         listener = BaseHub.add(self, evtype, fileno, cb)
-        if not oldlisteners:
-            # Means we've added a new listener
-            self.register(fileno, new=True)
-        else:
-            self.register(fileno, new=False)
+        try:
+            if not oldlisteners:
+                # Means we've added a new listener
+                self.register(fileno, new=True)
+            else:
+                self.register(fileno, new=False)
+        except IOError, ex:    # ignore EEXIST, #80
+            if get_errno(ex) != errno.EEXIST:
+                raise
         return listener
 
     def do_poll(self, seconds):

tests/hub_test.py

@@ -213,6 +213,42 @@ def test_repeated_selects(self):
         from eventlet.green import select
         self.assertRaises(ValueError, select.select, [-1], [], [])
         self.assertRaises(ValueError, select.select, [-1], [], [])
+
+
+from tests.patcher_test import ProcessBase
+class TestFork(ProcessBase):
+    @skip_with_pyevent
+    @skip_with_zmq
+    def test_fork(self):
+        new_mod = """
+import os
+import eventlet
+server = eventlet.listen(('localhost', 12345))
+t = eventlet.Timeout(0.01)
+try:
+    new_sock, address = server.accept()
+except eventlet.Timeout, t:
+    pass
+
+pid = os.fork()
+if not pid:
+    t = eventlet.Timeout(0.1)
+    try:
+        new_sock, address = server.accept()
+    except eventlet.Timeout, t:
+        print "accept blocked"
+        
+else:
+    kpid, status = os.wait()
+    assert kpid == pid
+    assert status == 0
+    print "child died ok"
+"""
+        self.write_to_tempfile("newmod", new_mod)
+        output, lines = self.launch_subprocess('newmod.py')
+        self.assertEqual(len(lines), 3, output)
+        self.assert_("accept blocked" in lines[0])
+        self.assert_("child died ok" in lines[1])
 
 
 class Foo(object):