Fix another common cause of SwitchingToDeadGreenlet or _socketobject is not iterable. Using exc_after to cancel a socket operation would leave the socket's fd in the hub, causing a spurious resumption of that greenlet when the socket operation completed in the future.

eventlet/api.py

@@ -295,7 +295,8 @@ def exc_after(seconds, exception_object):
             else: 
                 timer.cancel()
     """
-    return call_after(seconds, switch, getcurrent(), None, exception_object)
+    hub = get_hub()
+    return call_after(seconds, hub.exc_greenlet, getcurrent(), exception_object)
 
 
 def get_default_hub():

eventlet/hubs/hub.py

@@ -45,6 +45,7 @@ class BaseHub(object):
         self.readers = {}
         self.writers = {}
         self.excs = {}
+        self.waiters_by_greenlet = {}
 
         self.clock = clock
         self.greenlet = None
@@ -80,11 +81,19 @@ class BaseHub(object):
         self.readers[fileno] = read or self.readers.get(fileno)
         self.writers[fileno] = write or self.writers.get(fileno)
         self.excs[fileno] = exc or self.excs.get(fileno)
+        self.waiters_by_greenlet[greenlet.getcurrent()] = fileno
         
     def remove_descriptor(self, fileno):
         self.readers.pop(fileno, None)
         self.writers.pop(fileno, None)
         self.excs.pop(fileno, None)
+        self.waiters_by_greenlet.pop(greenlet.getcurrent(), None)
+
+    def exc_greenlet(self, gr, exception_object):
+        fileno = self.waiters_by_greenlet.pop(gr, None)
+        if fileno is not None:
+            self.remove_descriptor(fileno)
+        greenlib.switch(gr, None, exception_object)
 
     def exc_descriptor(self, fileno):
         exc = self.excs.get(fileno)

eventlet/hubs/libevent.py

@@ -59,7 +59,6 @@ class Hub(hub.BaseHub):
         sig = event.signal(signal.SIGINT, self.signal_received, signal.SIGINT)
         sig.add()
 
-
     def add_descriptor(self, fileno, read=None, write=None, exc=None):
         if read:
             evt = event.read(fileno, read, fileno)
@@ -74,12 +73,15 @@ class Hub(hub.BaseHub):
         if exc:
             self.excs[fileno] = exc
 
+        self.waiters_by_greenlet[greenlet.getcurrent()] = fileno
+
     def remove_descriptor(self, fileno):
         for queue in (self.readers, self.writers):
             tpl = queue.pop(fileno, None)
             if tpl is not None:
                 tpl[0].delete()
         self.excs.pop(fileno, None)
+        self.waiters_by_greenlet.pop(greenlet.getcurrent(), None)
 
     def abort(self):
         super(Hub, self).abort()