Bug #839075 (backport): document that highly recursive data cannot be pickled

diff --git a/Doc/lib/libpickle.tex b/Doc/lib/libpickle.tex
index f5c23f068d64c564e1b2210a2064ede1266771a2..74d289e13ca1ce3cf36044ac317e7b5352325882 100644 (file)
--- a/Doc/lib/libpickle.tex
+++ b/Doc/lib/libpickle.tex
@@ -395,6 +395,10 @@ section~\ref{pickle-protocol} for details)
 Attempts to pickle unpicklable objects will raise the
 \exception{PicklingError} exception; when this happens, an unspecified
 number of bytes may have already been written to the underlying file.
+Trying to pickle a highly recursive data structure may exceed the
+maximum recursion depth, a \exception{RuntimeError} will be raised
+in this case. You can carefully raise this limit with 
+\function{sys.setrecursionlimit()}.
 
 Note that functions (built-in and user-defined) are pickled by ``fully
 qualified'' name reference, not by value.  This means that only the