Index: Lib/pickle.py
===================================================================
--- Lib/pickle.py	(revision 63457)
+++ Lib/pickle.py	(working copy)
@@ -33,6 +33,7 @@
 import sys
 import struct
 import re
+import collections
 
 __all__ = ["PickleError", "PicklingError", "UnpicklingError", "Pickler",
            "Unpickler", "dump", "dumps", "load", "loads"]
@@ -221,7 +222,20 @@
         """Write a pickled representation of obj to the open file."""
         if self.proto >= 2:
             self.write(PROTO + chr(self.proto))
-        self.save(obj)
+        
+        # By faking recursion using generators, pickle is no longer dependent
+        # on python's recursion limit. This means that hugely recursive data
+        # structures can be pickled without a problem! It's also still just
+        # about as fast as it was, too.
+        callstack = collections.deque([self.save(obj)])
+        while callstack:
+            try:
+                result = callstack[-1].next()
+            except StopIteration:
+                callstack.pop()
+            else:
+                if result is not None:
+                    callstack.append(result)
         self.write(STOP)
 
     def memoize(self, obj):
@@ -270,7 +284,7 @@
         # Check for persistent id (defined by a subclass)
         pid = self.persistent_id(obj)
         if pid:
-            self.save_pers(pid)
+            yield self.save_pers(pid)
             return
 
         # Check the memo
@@ -283,7 +297,7 @@
         t = type(obj)
         f = self.dispatch.get(t)
         if f:
-            f(self, obj) # Call unbound method with explicit self
+            yield f(self, obj) # Call unbound method with explicit self
             return
 
         # Check for a class with a custom metaclass; treat as regular class
@@ -328,7 +342,7 @@
                                 "two to five elements" % reduce)
 
         # Save the reduce() output and finally memoize the object
-        self.save_reduce(obj=obj, *rv)
+        yield self.save_reduce(obj=obj, *rv)
 
     def persistent_id(self, obj):
         # This exists so a subclass can override it
@@ -337,7 +351,7 @@
     def save_pers(self, pid):
         # Save a persistent id reference
         if self.bin:
-            self.save(pid)
+            yield self.save(pid)
             self.write(BINPERSID)
         else:
             self.write(PERSID + str(pid) + '\n')
@@ -393,12 +407,12 @@
                 raise PicklingError(
                     "args[0] from __newobj__ args has the wrong class")
             args = args[1:]
-            save(cls)
-            save(args)
+            yield save(cls)
+            yield save(args)
             write(NEWOBJ)
         else:
-            save(func)
-            save(args)
+            yield save(func)
+            yield save(args)
             write(REDUCE)
 
         if obj is not None:
@@ -410,13 +424,13 @@
         # items and dict items (as (key, value) tuples), or None.
 
         if listitems is not None:
-            self._batch_appends(listitems)
+            yield self._batch_appends(listitems)
 
         if dictitems is not None:
-            self._batch_setitems(dictitems)
+            yield self._batch_setitems(dictitems)
 
         if state is not None:
-            save(state)
+            yield save(state)
             write(BUILD)
 
     # Methods below this point are dispatched through the dispatch table
@@ -545,7 +559,7 @@
         memo = self.memo
         if n <= 3 and proto >= 2:
             for element in obj:
-                save(element)
+                yield save(element)
             # Subtle.  Same as in the big comment below.
             if id(obj) in memo:
                 get = self.get(memo[id(obj)][0])
@@ -559,7 +573,7 @@
         # has more than 3 elements.
         write(MARK)
         for element in obj:
-            save(element)
+            yield save(element)
 
         if id(obj) in memo:
             # Subtle.  d was not in memo when we entered save_tuple(), so
@@ -597,7 +611,7 @@
             write(MARK + LIST)
 
         self.memoize(obj)
-        self._batch_appends(iter(obj))
+        yield self._batch_appends(iter(obj))
 
     dispatch[ListType] = save_list
 
@@ -612,7 +626,7 @@
 
         if not self.bin:
             for x in items:
-                save(x)
+                yield save(x)
                 write(APPEND)
             return
 
@@ -630,10 +644,10 @@
             if n > 1:
                 write(MARK)
                 for x in tmp:
-                    save(x)
+                    yield save(x)
                 write(APPENDS)
             elif n:
-                save(tmp[0])
+                yield save(tmp[0])
                 write(APPEND)
             # else tmp is empty, and we're done
 
@@ -646,7 +660,7 @@
             write(MARK + DICT)
 
         self.memoize(obj)
-        self._batch_setitems(obj.iteritems())
+        yield self._batch_setitems(obj.iteritems())
 
     dispatch[DictionaryType] = save_dict
     if not PyStringMap is None:
@@ -659,8 +673,8 @@
 
         if not self.bin:
             for k, v in items:
-                save(k)
-                save(v)
+                yield save(k)
+                yield save(v)
                 write(SETITEM)
             return
 
@@ -677,13 +691,13 @@
             if n > 1:
                 write(MARK)
                 for k, v in tmp:
-                    save(k)
-                    save(v)
+                    yield save(k)
+                    yield save(v)
                 write(SETITEMS)
             elif n:
                 k, v = tmp[0]
-                save(k)
-                save(v)
+                yield save(k)
+                yield save(v)
                 write(SETITEM)
             # else tmp is empty, and we're done
 
@@ -704,13 +718,13 @@
         write(MARK)
 
         if self.bin:
-            save(cls)
+            yield save(cls)
             for arg in args:
-                save(arg)
+                yield save(arg)
             write(OBJ)
         else:
             for arg in args:
-                save(arg)
+                yield save(arg)
             write(INST + cls.__module__ + '\n' + cls.__name__ + '\n')
 
         self.memoize(obj)
@@ -722,7 +736,7 @@
         else:
             stuff = getstate()
             _keep_alive(stuff, memo)
-        save(stuff)
+        yield save(stuff)
         write(BUILD)
 
     dispatch[InstanceType] = save_inst