Do the libraries support multithreading?

There is a version available (?) that is supposedly thread-safe: 5.4.13. According to what I have read, this will be the last version [read: "unofficial release"] before 6.0.0 which will be 100% thread safe. Prior versions will lead to very difficult programming problems. Also, I have read that this version is due "very soon".

Some threading libraries include patches to make libc work for you.

Please note that revising the standard libraries is no small task (gratuitous pun;). If you want to help, contact Libc Bugs [bug-glibc@prep.ai.mit.edu] or Ulrich Drepper [drepper@cygnus.com].

There is other work being done to accelerate reentrant libraries. For example, Wolfram Gloger [Wolfram.Gloger@dent.med.uni-muenchen.de] recently announced a "fast-malloc" which is thread safe called ptmalloc(). You can get it from [ftp://ftp.dent.med.uni-muenchen.de/pub/wmglo/ptmalloc.tar.gz].