Added assertion in greenpool to prevent infinite waits. Thanks to rtyler for the horrifying idea.

eventlet/greenpool.py

@@ -110,6 +110,9 @@ class GreenPool(object):
 
     def waitall(self):
         """Waits until all greenthreads in the pool are finished working."""
+        assert greenthread.getcurrent() not in self.coroutines_running, \
+                          "Calling waitall() from within one of the "\
+                          "GreenPool's greenthreads will never terminate."
         if self.running():
             self.no_coros_running.wait()
 

tests/greenpool_test.py

@@ -302,6 +302,11 @@ class GreenPool(tests.LimitedTestCase):
         p = greenpool.GreenPool()
         p.waitall()
         
+    def test_recursive_waitall(self):
+        p = greenpool.GreenPool()
+        gt = p.spawn(p.waitall)
+        self.assertRaises(AssertionError, gt.wait)
+
             
 class GreenPile(tests.LimitedTestCase):
     def test_pile(self):