The UpTools C++ Library, from the Universidad De Palermo (ie, University of Palermo), is an open source C++ library with facilities for load distribution and parallel processing, multi-threading, timers, memory management (with smart pointers for objects in multithreaded environments), regular expressions, common interfaces for different databases, database access in a multithreaded environment, networking support (DNS, SSL, TLS, sockets, etc), and so on. The library appears to be written for Linux.
UpTools C++ Library