Which version of the C library should I use with LinuxThreads?
The best choice by far is glibc 2, a.k.a. libc 6. It offers very good support for multi-threading, and LinuxThreads has been closely integrated with glibc 2. The glibc 2 distribution contains the sources of a specially adapted version of LinuxThreads. glibc 2 comes preinstalled as the default C library on most Linux distributions nowadays, such as RedHat 5 and up, and Debian 2 and up. Those distributions include the version of LinuxThreads matching glibc 2.