An asynchronous name lookup library was added. The proposal was circulated beforehand to get comments. No negative ones came in. Implemented by Ulrich Drepper. The RPC code is now thread safe.
Threads can now use the same service of different services at the same time.
One other change is noting worthwhile. The problem is some code in gcc which was necessary in libc5 but not with glibc. The reason is that there is a data type with the same name. Please test especially your multi-threaded applications since some changes to the cancelation handler code went in. This is even worse than previous releases at least 10 people or so replied.