Add doc about problems with parallel i/o

git-svn-id: https://svn.dealii.org/trunk@3322 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/lac/include/lac/swappable_vector.h b/deal.II/lac/include/lac/swappable_vector.h
index 7131812eac20e52c549a97d55b4cc25396d0a7fb..11bfd2d6503be0fcb9178357db19ee3d3f857e23 100644 (file)
--- a/deal.II/lac/include/lac/swappable_vector.h
+++ b/deal.II/lac/include/lac/swappable_vector.h
@@ -169,6 +169,25 @@ class SwappableVector : public Vector<number>
                                      * this function while the data
                                      * is still or already in memory
                                      * is allowed and has no effect.
+                                     *
+                                     * It is noted that versions of
+                                     * gcc up to at least version
+                                     * 2.95.2 are not thread-safe in
+                                     * the C++ standard
+                                     * library. Thus, parallel in-
+                                     * and/or output may sometimes
+                                     * lead to unreproducable
+                                     * crashes, segmentation faults,
+                                     * or bus errors of programs. You
+                                     * should therefore only call
+                                     * this function if either you
+                                     * are sure that the I/O library
+                                     * distributed with your compiler
+                                     * supports parallel
+                                     * writing/reading, or if you are
+                                     * sure that during the run-time
+                                     * of this function no other I/O
+                                     * operations are active.
                                      */
     void alert ();