Dear Boost.Thread experts, I wrote some libraries that are not multithreaded, but are supposed to be reentrant. I am compiling them from source. When I produce an executable that links these static libraries and invokes functions from these libraries from multiple threads via Boost.Threads, valgrind drd reports some race conditions in what appears to be straight forward memory access allocated with calloc. To be clear: the library function allocates some memory with calloc and later releases it. This memory is local to the function. I am wondering if I need to use any especial compiler flags when compiling the static libraries to make sure they are reentrant and compatible with Boost.Thread. In particular should I use or not use "-pthread" when compiling the libraries? Should I use "-pthread" when compiling and linking the final executable? I use gcc version 4.4.4 (Debian 4.4.4-1) and boost 1.42 (compiled from source because I am using Boost.Log). Thank you. Jorge Moraleda